Article: 224496 of rec.radio.amateur.antenna From: "Mike" References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Subject: Re: FIGHT! FIGHT! FIGHT! Date: Fri, 19 May 2006 19:17:06 +0800 Message-ID: <446da937$0$31531$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Hi. How's about you guys going to Dayton. I'm sure a Tag Fight could be arranged for you all. Two Pin Falls, Two Submissions,or a KO to decide the winner. Maybe if you all meet face to face, you will come to some common agreement, or this thread wii continue ad nausium. Regards Mike. Article: 224497 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 07:19:41 -0500 From: Tom Ring Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: <446db7dd$0$6149$39cecf19@news.twtelecom.net> Richard Clark wrote: > SBS and SRS (Stimulated Raman Scattering) would be suitable search > engine terms (esp. SBS threshold), but I warn you, they lead to > remarkably dense work where only one link in 20 will be accessible. > > 73's > Richard Clark, KB7QHC Thanks. tom K0TAR Article: 224498 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: Running wire close to HF transmit antenna Date: Fri, 19 May 2006 07:36:48 -0500 Message-ID: <126rev7aliu6r5a@corp.supernews.com> References: Ben Jackson wrote: > Let's say I have a free-standing vertical HF antenna transmitting about > 10wa, and I'd like to run wires to something at the tip. Say an > anemometer, or a temperature sensor. What would be the best way to run > the wire up the antenna? If the HF vertical is a pipe, is inside the > best bet? If it's shielded wire next to a solid antenna, will that > affect the radiation pattern of the antenna as a parasitic element? How > much energy at the tip of the antenna will couple into the wire? If the > wire is carrying low-speed digital data (eg for a 1-wire temperature > sensor), how much isolation would it need (choke, AC couple, opto-isolate, > etc) to avoid getting the HF into the digital signal? > > Thanks for any insight! > Hello Ben, If it were me I would find a way to attach it to my roof vents or somewhere else for sure. I'm just real skittish about damaging or false readings from my wxr station because of my rf. Gud luck to you. Butch KF5DE Article: 224499 of rec.radio.amateur.antenna From: "Vito" References: <44636b98$0$22188@dingus.crosslink.net> <446ca625$0$31271@dingus.crosslink.net> <1147971464.030262.29190@j33g2000cwa.googlegroups.com> Subject: Re: Elimination of CW is a loss in the number of ways we can communicate with other. Date: Fri, 19 May 2006 09:39:59 -0400 Message-ID: <446dcabe$0$31914@dingus.crosslink.net> "John S." wrote > Common in machine or human non-radio use? > Human non-radio, like mines and prisons. Article: 224500 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Running wire close to HF transmit antenna References: Message-ID: Date: Fri, 19 May 2006 08:54:01 -0500 Hi Ben Keeping on mind that the data rate going to/from the sensor is very low compared to the RF I *think* they will co-operate. Some thoughts though; - Opto systems have the problem that you need a power supply for the remote end. Using optical fibre is even a more elegant idea than wires but has a high-ish setup cost. You could of course use a IR LED/optotransistor config but as stated the power supply becomes an issue. - You could argue that infrequent TX RF on the antenna even if it affects the sensor (data) can be ignored . This of course depends on what you are using the weather data for. - If the weather data is a DC/AF level only you can allow RF onto the connection wire. Dont bother to try isolating it from the antenna at all. Dont even think of using shielded/coax. This way the effect on the antenna RF use will be small(er). You could get away with a choke/LPF or two at the antenna base, perhaps even with the use of coaxial stubs. (I'd start with a 1/4 wave open coaxial stub between each wire and antenna metalwork ground (ie where the antenna feed coax joins, then a other two further down)) Running the wire on the inside would of course be best for aesthetic and weather damage considerations. - I'd say the effect of a base decoupled wire on the antenna would be neglible next to that of the aneometer or any box at the antenna tip. You would be capacitively loading the antenna at the "worst" place. (assuming a current node like at the tip of a 1/4 wave) ie it would need a retune. Cheers Bob VK2YQA Ben Jackson wrote: > Let's say I have a free-standing vertical HF antenna transmitting about > 10wa, and I'd like to run wires to something at the tip. Article: 224501 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: Date: Fri, 19 May 2006 15:08:11 GMT Richard Clark wrote: > On Thu, 18 May 2006 19:01:58 -0500, Tom Ring > wrote: > > >>I had not heard of the Stokes shift, nor the scattering you mentioned. >>I have some looking up and reading to do. Which, of course, Cecil does >>not, since it's not a Xerox moment. > > > Hi Tom, > > It is pretty exotic, it only relates to radiation, reflection, > refraction, heat, and conduction, topics that are alien to discussion > here in more than TV Guide English it appears. Other difficult > concepts include linearity, coherence, mixing, and gain. > > Stokes shift is the change in frequency due to the non-linear response > of a media to excitation. Typically the excitation is a photon > interacting with a phonon with radiation scattering following. > Injecting an electron (current) can achieve the same end. The effect > of power clamping in fiber optic transmission lines is due to SBS > (Stimulated Brillouin Scattering) threshold. I've been working with > this (Stokes and Anti-Stokes Shift) for some 20 years, and it fails > easy access through a copier. > > The mention came only response to questions of linear response to what > at first glance would be a rather pedestrian transmission line > definition, but Glenn appears to have followed the clown instead of > pursuing his own question - he warned me it may have been pointless. > > SBS and SRS (Stimulated Raman Scattering) would be suitable search > engine terms (esp. SBS threshold), but I warn you, they lead to > remarkably dense work where only one link in 20 will be accessible. > > 73's > Richard Clark, KB7QHC Hi Richard, Stokes' law and the Raman effect can be found in physics texts dealing with quantum mechanics. Georg Joos, in his book _Theoretical Physics_ deals with such things. The reading is dense but the underlying concepts aren't too difficult. The difficulty might lie in understanding how they apply to this discussion. 73, Tom Donaly, KA6RUH Article: 224502 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Running wire close to HF transmit antenna Date: Fri, 19 May 2006 10:53:39 -0500 Message-ID: <23154-446DEA03-1125@storefull-3254.bay.webtv.net> References: Ben Jackson wrote: "Let`s say I have a free-standing vertical HF antenna about 10 wa, and I`d like to run wires to something at the tip." No problem. All the stations I`ve worked in, medium wave and shortwave, had lighted towers. Some also used the towers to support other antennas and devices. Medium wave towers have sampling loops bolted to them for remote current and phase indications. It`s dead simple. Conduit and coax are used to protect wires to devices and other antennas. Conduit and coax are firmly connected, top and bottom, at least, to the tower to shift most of the lightning to the lower-inductance tower. At the bottom across the base insulator, coax is coiled to create a reactance at least 10x the feedpoint impedance of the tower. Similarly, each of the other wires running up the tower for illumination or other purposes is broken at the base for a tower-lighting choke (or Austin transformer) to isolate the RF and lightning. It works like a charm. Best regards, Richard Harrison, KB5WZI Article: 224503 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Fri, 19 May 2006 12:16:53 -0500 Message-ID: <21360-446DFD85-1304@storefull-3257.bay.webtv.net> References: <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> Richard Clark, KB7QHC wrote: "Who. in your estimation, does qualify to discuss it?" If it`s about antennas, I nominate Kraus. If it`s about mathematics, many marhematicians qualify. In algebra, y = mx + b, (the point slope formula), is called linear because it is the graph of a straight line. In the discussion of transmission lines and antennas, you must admit that a uniform transmission line enforces a unique characteristic impedance (a resistance) on energy traveling in either direction. A resistance is linear because Ohm`s law prevails. In free-space, everyone agrees the characteristic impedance is about 377 ohms (a resistance). Kraus says on page 2 of his 1950 edition of "Antennas": "Let the transmission line now be connected to a dipole antenna as in Fig.1-2. The dipole acts as an antenna because it launches a free-space wave. However, it may also be regarded as a section of transmission line (see Sec. 1-2). In addition, it exhibits many of the characteristics of a resonator, since energy reflected from the ends of the dipole gives rise to a standing wave on the antenna. Thus a single device, in this case the dipole, exhibits simutaneously properties characteristic of an antenna, transmission line, and a resonator. Best regards, Richard Harrison, KB5WZI Article: 224504 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> Message-ID: <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> Date: Fri, 19 May 2006 17:47:40 GMT glenn.b.dixon@gmail.com wrote: > By 'simple antenna' I mean an antenna such as a wire dipole without > traps, baluns or other things that could degrade linearity. Seems the easiest measurement of nonlinearity would be the harmonics (if any) generated by the antenna that do not appear in the source signal. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224505 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> Message-ID: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> Date: Fri, 19 May 2006 18:45:19 GMT glenn.b.dixon@gmail.com wrote: > Richard, > > >>>Who, in your estimation, does qualify to discuss it? > > > I would like to hear from someone who has actually measured the > linearity of a simple antenna. I have not done this, so would only be > one guy with an opinion. Plenty of us around. > > By 'simple antenna' I mean an antenna such as a wire dipole without > traps, baluns or other things that could degrade linearity. Since the > linearity of antenna systems in general is in question, the simplest > setup that answers the question would be best. > > In the absence of measurement, can anyone comment on the modelling > software? Does it assume and model a linear system? If so, do we know > of any substantial nonlinear departures from the modelling software? > > Anyone? > > 73, > Glenn AC7ZN > In order to measure something, you have to define what it is, first. Cecil seems to think that in order for a simple dipole to be linear, the current magnitude measured along its length has to be sinusoidal in shape. Actually, though, I have it wrong. What he believes is that since he can't detect any harmonics emanating from a sinusoidally fed dipole, the current along its length must be a sinusoid. Actually, it's supposed to be impossible to represent the current distribution along a dipole using simple mathematical formulas because integral equations have to be solved that are impervious to any solution other than numerical approximation. That's why we need the various forms of NEC. Cecil is wrong for the reason I've given in another post, and, for reasons enumerated by Richard Clark. That won't stop the flow of bellicose posts from him, though. 73, Tom Donaly, KA6RUH Article: 224506 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> Message-ID: Date: Fri, 19 May 2006 18:46:58 GMT Cecil Moore wrote: > glenn.b.dixon@gmail.com wrote: > >> By 'simple antenna' I mean an antenna such as a wire dipole without >> traps, baluns or other things that could degrade linearity. > > > Seems the easiest measurement of nonlinearity would be the > harmonics (if any) generated by the antenna that do not > appear in the source signal. Which wouldn't tell you a single thing about the current distribution along the length of the dipole. 73, Tom Donaly, KA6RUH Article: 224507 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: <7Cobg.29178$4L1.28624@newssvr11.news.prodigy.com> Date: Fri, 19 May 2006 19:01:23 GMT Richard Clark wrote: > On Fri, 19 May 2006 15:08:11 GMT, "Tom Donaly" > wrote: > > >> Stokes' law and the Raman effect can be found in >>physics texts dealing with quantum mechanics. Georg Joos, in >>his book _Theoretical Physics_ deals with such things. The reading >>is dense but the underlying concepts aren't too difficult. The >>difficulty might lie in understanding how they apply to this >>discussion. > > > Hi Tom, > > Certainly Joos would give some entry into the field, but finding work > as accessible outside of a bookstore or library (in other words, > through a search engine) makes for drinking out of a fire hose to > quench a sip's worth of thirst. > > Insofar as HOW this applies, I've spoken to that and Tom shows > interest. That alone goes beyond the typical churning that passes for > discussion. The point is that these underlying concepts are fairly > simple as you imply and they are certainly not remote from the usual > topics of consideration here. What they lack is specifics that relate > to our common applications, and there too I've offered discussion. > However, few seem inspired to travel those paths and that fault can > hardly be laid at my doorstep. > > 73's > Richard Clark, KB7QHC Hi Richard, I didn't intend any criticism. People like Cecil, with home-grown theories, don't ever seem to want things considered in depth. That's understandable from a psychological standpoint, but it isn't any help to the rest of us when some of the things the theory ignores become significant. In the case of antennas, practically everything is significant. 73, Tom Donaly, KA6RUH Article: 224508 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 14:24:07 -0500 From: Tom Ring Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: <446e1b59$0$1004$39cecf19@news.twtelecom.net> Richard Clark wrote: > On Fri, 19 May 2006 15:08:11 GMT, "Tom Donaly" > wrote: > > >> Stokes' law and the Raman effect can be found in >>physics texts dealing with quantum mechanics. Georg Joos, in >>his book _Theoretical Physics_ deals with such things. The reading >>is dense but the underlying concepts aren't too difficult. The >>difficulty might lie in understanding how they apply to this >>discussion. > > > Hi Tom, > > Certainly Joos would give some entry into the field, but finding work > as accessible outside of a bookstore or library (in other words, > through a search engine) makes for drinking out of a fire hose to > quench a sip's worth of thirst. > > Insofar as HOW this applies, I've spoken to that and Tom shows > interest. That alone goes beyond the typical churning that passes for > discussion. The point is that these underlying concepts are fairly > simple as you imply and they are certainly not remote from the usual > topics of consideration here. What they lack is specifics that relate > to our common applications, and there too I've offered discussion. > However, few seem inspired to travel those paths and that fault can > hardly be laid at my doorstep. > > 73's > Richard Clark, KB7QHC And a web search produced a couple very good links out of the first 20. One was a great discussion of problems in long optical fibers, and some relatively simple ways to work around some of them, or at least to mitigate them. tom K0TAR Article: 224509 of rec.radio.amateur.antenna From: "The always Benevolent dbu." Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Fri, 19 May 2006 21:07:17 GMT In article , Dave wrote: > I use a "multi-band center fed doublet" for 80 through 10 meters. It is > fed with 600 ohm open wire tuned feeders. Feeder length is just enough > to get from the tuner to the antenna , about 180 feet. The > tuner/balun are bonded together and connected to electrical neutral. > > No RF in the shack on 80 through 10. Well that's not really true. I'm > sitting in the near field; but, I don't have RF hotspots on anything in > the station at 1KW. > Thanks Dave. I just reconfigured my feedline and shortened it up also re-doing the physical layout. I have used this setup, open wire feed with 126 ft center fed wire for years and have never had a RF feedback problem in the shack. I asked the question because in the process of reconfiguration I consulted several sources which illuminated inconsistencies regarding length. From the responses I received here there does not seem to be any agreement on length and my question was not answered, at least not to my satisfaction. Anyway so far I'm ok with my current setup. 73 Dale, K9VUJ > > > dale.j. wrote: > > > What is the correct way to determine the non-resonant feedline length of > > a multiband doublet using 450 ohm open wire. > > > > tnx > > Dale > > -- "I'm not going to have some reporters pawing through our papers. We are the president." --Hillary Clinton commenting on the release of subpoenaed documents. Article: 224510 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Fri, 19 May 2006 16:01:53 -0500 Message-ID: <23819-446E3241-1372@storefull-3252.bay.webtv.net> References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> Tom Donaly, KA6RUH wrote: "Actually, it`s supposed to be impossible to represent the current distribution along a dipole using simple mathematical formulas because integral equations have to be solved that are impervious to any solution other than numerical approximation." How many places do you attach to pi? First, what is linearity? It is the absence of nonlinearity. Millman and Seely wrote on page 525 of the 1951 edition of "Electronics" (one of my old textbooks): "Because of this nonlinear characteristic of the dynamic curve over the operating range, the wave form of the output wave differs slightly from that of the grid-exciting-voltage waveshape. Distortion of this type is called "nonlinear" or "amplitude" distortion.." All of the antennas I`ve worked with had no noticeable amplitude distortion. They caused no harmonics or mixing products. On page 235 of Kraus` 1950 edition of "Antennas" he sets out to solve Hallen`s equation for current distribution. On page 239, Kraus writes: "It is generally assumed that the current distribution of an infinitesimally thin antenna is sinusoidal, and that the phase is constant over a 1/2-wavelength interval, changing abruptly by 180-degrees between intervals." You can take what Kraus says to the bank. Best regards, Richard Harrison, KB5WZI Article: 224511 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 16:16:42 -0500 From: Tom Ring Subject: Spark 2006 Message-ID: <446e35bc$0$6155$39cecf19@news.twtelecom.net> This is from the Yahoo Live Wire group. I thought some here might be interested in it. tom K0TAR ------------------------------------- Message 8 From: "David H Hatch" n9zrt@arrl.net Date: Wed May 17, 2006 5:26pm(PDT) Subject: Spark gap - Marconi 2006 Hi Live-Wires, With permission, I am posting the following regarding the Marconi 2006 event. -------------- Dan W7OIL has informed the team leader that he is nearly ready with the passive receiver and adaptations for an INC. So today, WI7B is happy to announce they have achieved spark in their 800 KHz rotary spark gap transmitter. They built it from a "Franken'd" Chevy V8 single point distributor and spark coil. With 7 VDC it generates a hefty 0.5 inch spark every 1/500 second (500 Hz rep rate). I've attached photos of the setup and the spark gap, both un-energized and energized. See the progress on the sparkgap here: http://www.wireservices.com/n9zrt/Marconi-06/ Jim NY7T and W7OIL will be adding the LCR circuitry to the spark gap, then move it out the "ranch" to couple to a 375m quarter wave antenna. The group has an STA from the FCC-OET to operate an 800 KHz spark gap transmitter. Callsign WC9XLG. They are legal. Article: 224512 of rec.radio.amateur.antenna Subject: Re: Elimination of CW is a loss in the number of ways we can communicate with other. From: Slow Code References: <1147047627.949564.83230@y43g2000cwc.googlegroups.com> <1147549161.064623.59130@j33g2000cwa.googlegroups.com> <1147586170.894157.292250@d71g2000cwd.googlegroups.com> <38c8.gop.17.1@news.alt.net> <1147832357.964390.122730@i40g2000cwc.googlegroups.com> Message-ID: Date: Fri, 19 May 2006 21:44:49 GMT "Dan/W4NTI" wrote in news:jnOag.3495$y4.724@newsread2.news.pas.earthlink.net: > > "an_old_friend" wrote in message > news:1147832357.964390.122730@i40g2000cwc.googlegroups.com... >> >> Dan/W4NTI wrote: >>> "Not Lloyd II" wrote in message >>> news:38c8.gop.17.1@news.alt.net... >> >>> 4 >> >> this is not a golfign NG dan I would expect you topay attention but you >> insit on disappointing me >>> >>> Dan/W4NTI >> > > Try a spell check you goofball. I don't give a damn if you are dyslexic > or not. That does not preclude you using a spell checker. > > Dan/W4NTI For a spell checker to work good you need to be reasonable close to the word and he ain't even reasonably close. sc Article: 224513 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Fri, 19 May 2006 21:50:35 GMT On Fri, 19 May 2006 21:07:17 GMT, "The always Benevolent dbu." wrote: >inconsistencies regarding length. From the responses I received here >there does not seem to be any agreement on length and my question was >not answered, at least not to my satisfaction. That statement reflects your ability to comprehend what was written by many, rather than what was written. If you expected a specific length as implied by your question "What is the correct way to determine the non-resonant feedline length of a multiband doublet using 450 ohm open wire." then you have been dissapointed. The consistent answer (even if not always well expressed) was that length is not particularly critical, though there may be some length / frequency combinations (that are very dependent on your particular implementation and equipment) that may challenge your ATU. I go along with the advice to use a convenient length of feedline, and if it is challenging to match up with the ATU, then lengthen the feedline a little. Your dissapointment is perhaps caused by your expectation of a specific length. Owen -- Article: 224514 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Fri, 19 May 2006 21:48:38 GMT In article , Dan Richardson <> wrote: > On Fri, 19 May 2006 21:07:17 GMT, "The always Benevolent dbu." > wrote: > > >In article , > > Dave wrote: > > > >> I use a "multi-band center fed doublet" for 80 through 10 meters. It is > >> fed with 600 ohm open wire tuned feeders. Feeder length is just enough > >> to get from the tuner to the antenna , about 180 feet. The > >> tuner/balun are bonded together and connected to electrical neutral. > >> > >> No RF in the shack on 80 through 10. Well that's not really true. I'm > >> sitting in the near field; but, I don't have RF hotspots on anything in > >> the station at 1KW. > >> > > > >Thanks Dave. I just reconfigured my feedline and shortened it up also > >re-doing the physical layout. I have used this setup, open wire feed > >with 126 ft center fed wire for years and have never had a RF feedback > >problem in the shack. I asked the question because in the process of > >reconfiguration I consulted several sources which illuminated > >inconsistencies regarding length. From the responses I received here > >there does not seem to be any agreement on length and my question was > >not answered, at least not to my satisfaction. > > > >Anyway so far I'm ok with my current setup. > > > >73 > >Dale, K9VUJ > > > > It seems to me that we need to remember that radiation coming from the > feed line is cause by common current. If the feed line is balanced (no > common mode current) there will be no radiation from the feed line > regardless of the line's impedance or the feed point impedance. > > Danny, K6MHE > > In my many years I have come to a conclusion that one > useless man is a shame, two is a law firm, and three > or more is a congress. - John Adams > > email: k6mhearrlnet > http://www.k6mhe.com/ I think you have brought up a good point as to the balance of the parallel wires which is self canceling. Maybe I will be able to sleep once again tonight... 73 Dale -- Email: dalej2@mac.com Article: 224515 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: Multiband doublet feedline length Date: Fri, 19 May 2006 22:22:58 -0000 Message-ID: <126sha2opvg86eb@corp.supernews.com> References: In article , The always Benevolent dbu. wrote: >Thanks Dave. I just reconfigured my feedline and shortened it up also >re-doing the physical layout. I have used this setup, open wire feed >with 126 ft center fed wire for years and have never had a RF feedback >problem in the shack. I asked the question because in the process of >reconfiguration I consulted several sources which illuminated >inconsistencies regarding length. From the responses I received here >there does not seem to be any agreement on length and my question was >not answered, at least not to my satisfaction. Well, let me take a crack at it, if I may. First-off: I don't think there's necessarily any single "right" length of feedline, even for a single individual installation. There are certainly a number of "wrong" lengths of feedline: - The classic one - length is too short to reach the rig/transmatch - Too long - feedline drapes on the ground, is looped around near metallic objects, etc. - and there are excessive losses or shock hazards - End-of-feedline impedance on one or more bands is outside the range which can be matched properly. The first two sets of conditions are fairly easy to pin down. :-) The third is, I think, the place where the interesting variables come in. Transmatches aren't all equal, by any means, in the ranges of impedances that they can match (and the matchable impedances don't necessarily form a nice SWR-value circle on the Smith chart!), or the losses in the tuner, or the amount of power that the tuner can handle before it starts to suffer from arcing or balun overheating/saturation. It's likely that in any given installation, there will be multiple lengths of feedline which will allow a match on a particular set of bands. The matches will probably vary in efficiency and Q. Which one will be "best" is, to some extent, a value judgement by the installer and will depend on how the station is going to be operated. For example, if you spend most of your time operating on one or two bands, you might choose a feedline length which allows efficient and fairly low-Q transmatch settings, so that you don't have to adjust the match as often (or as critically) when QSY'ing within a band. Now... how to evaluate the possibilities. Here's one approach which might be worth trying - it's a bunch of work but should let you end up with some useful data. [1] Grab a whole bunch of Smith chart blanks (or get some good Smith chart software, or some other software which lets you handle impedance transformations conveniently). [2] Figure out the minimum and maximum lengths of feedline which would be physically acceptable in your installation... from the shortest which will reach the rig, to the longest which can conveniently be zig-zagged back and forth between feedpoint and rig. Convert these lengths to electrical length (i.e. divide by the feedline's velocity factor, if it's much less than 1.0). [3] For each band, convert the minimum feedline length into wavelengths, modulo 1/2 wavelength (180 degrees). Also, calculate the difference between minimum and maximum feedline lengths in wavelengths. If it's more than 180 degrees, just call it 180. [4] Determine the range of impedances that your transmatch can handle, on each band that you're interested in working. You _may_ be able to use whatever blanket marketing/spec statement the tuner manufacturer provides (e.g. matches any SWR < 10:1, "all impedances from 25 to 1000 ohms", etc.) but it wouldn't hurt to run some tests yourself. You may wish to rule out some impedances even if they're theoretically matchable - e.g. a T-match tuner can often produce a "match" to a near-short-circuit, but the losses in the tuner are so high that it's not worth the bother. [5] For each band, plot the range of matchable impedances on a Smith chart which is normalized to the nominal impedance of your balanced feedline. Use one Smith chart per band to avoid confusion. [6] Choose the length of your doublet, based on space available and/or desired pattern on one or more bands and/or lore and/or any other criteria you desire. [7] For each band, use appropriate tables to determine the feedpoint impedance of the doublet on the band in question. You may wish to calculate several values when the band is fairly wide (e.g. 80 meters). [8] Plot the doublet's feedpoint impedance for each band on that band's Smith chart. [9] Using a compass centered at the Smith chart's origin, rotate the feedpoint impedance "towards generator" by the number of degrees corresponding to the shortest-possible feedline length, as calculated in step 3. Plot this point. [10] Use the compass (centered at the origin) to draw an arc from this point, in the "towards generator" direction, for the number of degrees corresponding to the difference between minimum and maximum feedline lengths. What this should leave you with (we hope) is a chart for each band, which shows where the antenna's feedpoint impedance, transformed by the feedline, falls inside the range of impedances that the transmatch can handle. If the impedance arc comes near the centroid of one of the "We can match this" circle/blob, then the closest-to-centroid point on the arc would correspond to a feedline length which might be a very good one for that band. If the arc doesn't enter a band's matchable circle/blob at all, or just barely enters it, then you may wish to go back to Step 6, pick a different doublet length, and try again. Now, what you can do is take a piece of paper and draw a straight line. Put the minimum feedline length at one end and the maximum at the other. For each band, look at the impedance arc, record the sections at which it's outside of the matchable-impedances blob (measure the number of electrical degrees of rotation from the load), and figure out the feedline lengths that these unmatchable sections correspond do. Use a colored marker to denote these lengths on the straight "minimum to maximum feedline" graph. Borrow color markers or crayons from your kids so that you have one color per band :-) Once you've finished doing this for all of the bands you're interested in, take a look at the straightline graph of feedline length. If you're unlucky, *every* point on that graph will be colored as "not matchable" on one or more of the bands that you care about. If so, you can go back to Step 6 and try a different doublet length, or you can resign yourself to having to switch between two different lengths of feedline when QSYing. If you're not unlucky, there will be at least one range of feedline lengths which can be matched on all bands. If so, I'd suggest choosing a length which causes the impedance arcs you plotted to fall near the centroids of the matchable-impedance areas, on the bands that you use most heavily. The above is very much a manual procedure, requiring at least an hour of calculating and plotting and cussing. There are almost certainly some software tools which can be used to automate and simplify this process. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224516 of rec.radio.amateur.antenna From: Ron Subject: Re: ARS License Numbers Date: 19 May 2006 18:17:15 EDT Message-ID: <446E4561.3090805@yahoo.com> References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> So how many Ham died within that 6 year period. Remember we are a OLDER population. Slow Code wrote: > N2EY@AOL.COM wrote in > news:1148005814.174874.234520@38g2000cwa.googlegroups.com: > > >>These are the numbers of current, unexpired >>amateur radio licenses held by individuals >>on the stated dates, and the percentage of >>the total number of active licenses that >>class contains: >> >>As of May 14, 2000: >> >>Novice - 49,329 (7.3%) >>Technician - 205,394 (30.4%) >>Technician Plus - 128,860 (19.1%) >>General - 112,677 (16.7%) >>Advanced - 99,782 (14.8%) >>Extra - 78,750 (11.7%) >> >>Total Tech/TechPlus - 334,254 (49.5%) >> >>Total General/Advanced/Extra - 291,209 (43.2%) >> >>Total all classes - 674,792 >> >> >>As of May 15, 2006: >> >>Novice - 25,182 (3.8%) [decrease of 24,147] >>Technician - 280,160 (42.6%) [increase of 74,766] >>Technician Plus - 39,130 (6.0%) [decrease of 89,730] >>General - 133,240 (20.2%) [increase of 20,563] >>Advanced - 72,315 (11.0%) [decrease of 27,467] >>Extra - 108,005 (16.4%) [increase of 29,255] >> >>Total Tech/TechPlus - 319,290 (48.6%) [decrease of 14,964] >> >>Total General/Advanced/Extra - 313,560 (47.6%) [increase of 22,351] >> >>Total all classes - 658,032 (decrease of 16,760) > > > > > > I predicted and warned you all this would happen, but none of you wouldn't > listen. > > Good Hams upset over all the Lids and CB'er like behavior on the bands as > a result of dumbing down license requirements are leaving the hobby. I > can't say I blame them and I hate to see them go. > > On the bright side, there's a lot more ham gear on eBay you can bid on. > > sc Article: 224517 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Fri, 19 May 2006 23:03:49 GMT In article , Owen Duffy wrote: > On Fri, 19 May 2006 21:07:17 GMT, "The always Benevolent dbu." > wrote: > > > >inconsistencies regarding length. From the responses I received here > >there does not seem to be any agreement on length and my question was > >not answered, at least not to my satisfaction. > > That statement reflects your ability to comprehend what was written by > many, rather than what was written. > > If you expected a specific length as implied by your question "What is > the correct way to determine the non-resonant feedline length of a > multiband doublet using 450 ohm open wire." then you have been > dissapointed. > > The consistent answer (even if not always well expressed) was that > length is not particularly critical, though there may be some length / > frequency combinations (that are very dependent on your particular > implementation and equipment) that may challenge your ATU. > > I go along with the advice to use a convenient length of feedline, and > if it is challenging to match up with the ATU, then lengthen the > feedline a little. > > Your dissapointment is perhaps caused by your expectation of a > specific length. > > Owen > -- I keep going back to my very old ARRL antenna handbood which shows a chart of favorable lengths of feedline. Is it wrong? I also would like to point out W8JI website and the lengths of feedline that he recommends, which seems to be consistent with my ARRL handbook, 1960 edition, for this type antenna: http://www.w8ji.com/short_dipoles_and_problems.htm Arrow down. -- Email: dalej2@mac.com Article: 224518 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Fri, 19 May 2006 23:43:02 GMT On Fri, 19 May 2006 23:03:49 GMT, "dale.j. " wrote: >I keep going back to my very old ARRL antenna handbood which shows a >chart of favorable lengths of feedline. Is it wrong? My 2000 ARRL Handbook describes a 135' multiband dipole antenna but does not make any recommendations on preferred feedline lengths. Perhaps they have changed their mind since your edition was published. Given sufficiently good transmission line, lengths to avoid are only lengths to avoid because they present a load that the tuner cannot efficiently transform, or the voltage exceeds the capability of the tuner. Highest voltages usually occur at frequencies much lower than the first parallel resonance... so avoiding resonance doesn't address the most significant region of high voltage. >I also would like to point out W8JI website and the lengths of feedline >that he recommends, which seems to be consistent with my ARRL handbook, >1960 edition, for this type antenna: > >http://www.w8ji.com/short_dipoles_and_problems.htm > He does more than recommend a feedline length in isolation of other parameters. Tom's article is relevant and interesting. You will see that he links to articles by Cebik and myself on the G5RV. Also relevant to the multiband dipole application is the analysis in my article at http://www.vk1od.net/LOLL/index.htm and its reference documents. To get off the 1960 tram, factors that are relevant are: - they probably did not foresee the WARC bands and design to include those bands; - the regions where efficient transformation is a problem are usually very narrow, but quite dependent on the exact implementation (including proximity of other conducting objects, ground / weather conditions), and locating them outside amateur bands may require in-situ tuning. Owen -- Article: 224519 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Fri, 19 May 2006 23:44:37 GMT On Fri, 19 May 2006 21:48:38 GMT, "dale.j. " wrote: >I think you have brought up a good point as to the balance of the >parallel wires which is self canceling. Balanced current may be self cancelling, but currents are not self balancing. Owen -- Article: 224520 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Sat, 20 May 2006 00:45:29 -0000 Message-ID: <126spl9mu0d4079@corp.supernews.com> References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> <1148083790.131137.181880@j33g2000cwa.googlegroups.com> In article <1148083790.131137.181880@j33g2000cwa.googlegroups.com>, wrote: >Maybe, like so many other threads in this group, we are discussing >orthogonal concepts. I believe you're correct. As I see it, in the *general* sense, linearity refers to a relationship between two variables, where the relationship is one of OUT = IN * F + C where F and C are constants (plus a dimensional factor in many cases). In other words, it's a straight-line relationship (hence, the name) between two variables of the same or different dimension. The sort of "linearity" that people usually refer to in electronics, involves voltages and currents (vs. one another). A theoretically perfect resistor, capacitor, or inductor is linear, because (e.g.) the peak current through it has a strictly linear relationship to the peak voltage across it. A semiconductor junction is described as nonlinear, because the current through it is not related to the voltage across it in a strictly linear relationship. The sort of "linearity" which Cecil seems to be referring to (if I understand what he's written correctly) involves a completely different sort of relationship. It's not current-vs-voltage, or voltage-vs-current - it's current-vs-distance. If I recall correctly, an infinitesimally-short "monopole" has a current-vs-distance relationship which is close to linear. A half-wave monopole does not. Nonlinearities of this sort would have entirely different effects on an antenna system than nonlinearities of the voltage-vs-current sort. They're two different beasts entirely. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224521 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 20:28:16 -0500 From: Tom Ring Subject: Re: ARS License Numbers References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> Message-ID: <446e70b0$0$1010$39cecf19@news.twtelecom.net> Slow Code wrote: > > I predicted and warned you all this would happen, but none of you wouldn't > listen. > > Good Hams upset over all the Lids and CB'er like behavior on the bands as > a result of dumbing down license requirements are leaving the hobby. I > can't say I blame them and I hate to see them go. > > On the bright side, there's a lot more ham gear on eBay you can bid on. > > sc And what do these numbers prove? Not a bleeping thing. I don't think any correlation exists between them and current behavior on HF, which I assume, possibly incorrectly, that you are refering to. The biggest idiots on 20m, for instance, are on 14275, both sides are guilty, and I am quite sure that they all got their tickets with CW required. And the problem stations on 75 are quite the same. Which also proves nothing either way. The cleanest, most public oriented operators are on 2m and 70cm, and many, or maybe most, of them did not have to pass any CW exam. They participate in Skywarn, emergency drills, and tons of other things. By and large they are good citizens. The bad actors I have seen come from all parts of the amateur community, with probably the worst from the longest licensed, who seem to feel they have some sort of rights from being around a long time. My personal sample could be wrong, but I don't think so; I've been around a while, too. The older generation always predicts that the current one is going to cause the end of the world. Or whatever imagined disaster they are concerned about. And they are always wrong. tom K0TAR Article: 224522 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> Message-ID: Date: Sat, 20 May 2006 04:50:43 GMT Richard Clark wrote: > In other words, the non-linearity shown by the lack of > congruence to the Cosine curve is not a presumption of non-linearity > by the modeler; it is merely reporting an analysis. You are being fooled by an illusion. Any deviation from single frequency sinusoidal signals would generate harmonics which we know doesn't happen. Your "non-linearity" is not really there. For instance, a decrease in VF may compress the waveform but that is not non-linearity. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224523 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 05:04:21 GMT Tom Donaly wrote: > What he believes is that > since he can't detect any harmonics emanating from a sinusoidally > fed dipole, the current along its length must be a sinusoid. The non-existence of harmonics is prima facie evidence that only single frequency sinusoids exist. A properly functioning antenna system is linear. Any perceived non-linearity is an illusion. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224524 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 05:19:41 GMT Tom Donaly wrote: > Cecil Moore wrote: >> Seems the easiest measurement of nonlinearity would be the >> harmonics (if any) generated by the antenna that do not >> appear in the source signal. > > Which wouldn't tell you a single thing about the current > distribution along the length of the dipole. Yes it would. It would be proof that the current distribution along the length of the dipole is sinusoidal no matter what your illusionary perceptions are telling you. For standing wave antennas, if the source is a pure single frequency sine wave and if no harmonics are generated by the antenna system: 1. The forward wave is sinusoidal. 2. The reflected wave is sinusoidal and coherent with the forward wave. 3. Their superposition results in a sinusoidal standing wave with the same angular velocity. Any non-linearity would introduce harmonics. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224525 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <7Cobg.29178$4L1.28624@newssvr11.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 05:25:34 GMT Tom Donaly wrote: > People like Cecil, with > home-grown theories, don't ever seem to want things considered in > depth. That's understandable from a psychological standpoint, but > it isn't any help to the rest of us when some of the things the theory > ignores become significant. In the case of antennas, practically > everything is significant. All of the theories I am quoting were developed long before I was born. Almost every technical explanation starts out with simple concepts and proceeds to more complex concepts. For the sake of teaching and understanding simple concepts, the secondary variables are often ignored for the time being. Thus, every textbook on transmission lines starts off with an explanation of lossless lines with perfectly resistive characteristic impedances even though such lines don't exist in reality. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224526 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: ARS License Numbers References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> Message-ID: <1Sxbg.10745$fb2.3968@newssvr27.news.prodigy.net> Date: Sat, 20 May 2006 05:32:45 GMT Slow Code wrote: > I predicted and warned you all this would happen, but none of you wouldn't > listen. If none of us wouldn't listen, doesn't that mean that all of us did listen? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224527 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> Message-ID: Date: Sat, 20 May 2006 05:36:24 GMT Richard Clark wrote: > How much distortion has to exist before you hear it? As this directly > relates to your quoted selection, are we to believe that distortion > does not exist if you cannot perceive it? How about: Distortion can be measured. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224528 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> <1148083790.131137.181880@j33g2000cwa.googlegroups.com> <126spl9mu0d4079@corp.supernews.com> Message-ID: Date: Sat, 20 May 2006 05:47:55 GMT Dave Platt wrote: > The sort of "linearity" which Cecil seems to be referring to (if I > understand what he's written correctly) involves a completely > different sort of relationship. It's not current-vs-voltage, or > voltage-vs-current - it's current-vs-distance. Assuming thin constant diameter wires with a constant Z0 and VF. If the diameter of the wire changes, or Z0 changes, or VF changes, the 'K' term in the cos(KX) expression changes. A change in a constant does NOT produce non-linearity in a linear system. Just because a wave slows down in a medium with a low VF doesn't mean that the system has gone non-linear. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224529 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> Message-ID: Date: Sat, 20 May 2006 05:53:50 GMT Tom Donaly wrote: > Kraus was talking about distribution over _length_. Of course, Kraus is talking about the cos(KX) term where 'X' is _length_ and 'K' is the constant that converts that _length_ into degrees. Given 'K', _length_ and degrees are perfectly correlated. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224530 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 10:50:22 GMT In article , Owen Duffy wrote: > On Fri, 19 May 2006 23:03:49 GMT, "dale.j. " > wrote: > > >I keep going back to my very old ARRL antenna handbood which shows a > >chart of favorable lengths of feedline. Is it wrong? > > My 2000 ARRL Handbook describes a 135' multiband dipole antenna but > does not make any recommendations on preferred feedline lengths. > > Perhaps they have changed their mind since your edition was published. > > Given sufficiently good transmission line, lengths to avoid are only > lengths to avoid because they present a load that the tuner cannot > efficiently transform, or the voltage exceeds the capability of the > tuner. > > Highest voltages usually occur at frequencies much lower than the > first parallel resonance... so avoiding resonance doesn't address the > most significant region of high voltage. > > >I also would like to point out W8JI website and the lengths of feedline > >that he recommends, which seems to be consistent with my ARRL handbook, > >1960 edition, for this type antenna: > > > >http://www.w8ji.com/short_dipoles_and_problems.htm > > > > He does more than recommend a feedline length in isolation of other > parameters. > > Tom's article is relevant and interesting. > > You will see that he links to articles by Cebik and myself on the > G5RV. > > Also relevant to the multiband dipole application is the analysis in > my article at http://www.vk1od.net/LOLL/index.htm and its reference > documents. > > To get off the 1960 tram, factors that are relevant are: > - they probably did not foresee the WARC bands and design to include > those bands; > - the regions where efficient transformation is a problem are usually > very narrow, but quite dependent on the exact implementation > (including proximity of other conducting objects, ground / weather > conditions), and locating them outside amateur bands may require > in-situ tuning. > > Owen > -- Thanks for all the links which I am reading. My dipole is about 126 feet long which should be about right for 3.7 Mhz. I mostly use it on 75 M. The new feedline I have installed is a bit shorter than what I was using, I think it's now around 47 feet, the old stuff was 50 plus feet. I notice my Johnson matchbox now finds it somewhat difficult to tune up this antenna on 40 M so I may have to add on a few feet. A couple of years ago I had two loading coils on each leg of the tuner output and the whole thing was a perfect match on 75 and 40, all I had to do was change the bandswitch on the matchbox, nothing else. I guess I'll just not worry about length of feedline only to make it tune nicely and fit the physical space from the antenna. 73 dale -- Email: dalej2@mac.com Article: 224531 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 12:17:53 GMT dale.j. wrote: > Thanks for all the links which I am reading. My dipole is about 126 > feet long which should be about right for 3.7 Mhz. I mostly use it on > 75 M. The new feedline I have installed is a bit shorter than what I > was using, I think it's now around 47 feet, the old stuff was 50 plus > feet. I notice my Johnson matchbox now finds it somewhat difficult to > tune up this antenna on 40 M so I may have to add on a few feet. Did you take a look at the information on my web page at: http://www.qsl.net/w5dxp/notuner.htm It tells you everything you need to know about that antenna including why 47 feet is not the best feedline length on 40m. In particular, the chart at: http://www.qsl.net/w5dxp/pnts130.gif shows the best lengths for 40m to be 30 feet or 92 feet. A good compromise single length for all-HF-band operation is 100 feet. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224532 of rec.radio.amateur.antenna From: Ron Subject: Re: ARS License Numbers Date: 20 May 2006 10:24:01 EDT Message-ID: <446F27FE.4000903@yahoo.com> References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> >> On the bright side, there's a lot more ham gear on eBay you can bid on. > > > But...what good does having a bunch of gear if there is nobody to talk > to or listen to? I guess it's good if you're starting a radio museum... Actually there is less of the good stuff on eBay than there was 2 years ago. Plus prices for the rare stuff still keeps going up. Article: 224533 of rec.radio.amateur.antenna From: Ron Subject: Re: ARS License Numbers Date: 20 May 2006 10:27:46 EDT Message-ID: References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> >>I don't think any correlation exists between them and current behavior >>on HF, which I assume, possibly incorrectly, that you are refering to. > >>The biggest idiots on 20m, for instance, are on 14275, both sides are >>guilty, and I am quite sure that they all got their tickets with CW >>required. And the problem stations on 75 are quite the same. Which >>also proves nothing either way. > > > it does prove that CW testing is at best poor proof of screening out > bad ops Yup if you check it out most of the crap on HF is from old farts that passed their tests with the CW requirement. From JT Mon May 22 21:17:25 EDT 2006 Article: 224534 of rec.radio.amateur.antenna From: JT (jt@trek.net) Newsgroups: rec.radio.amateur.antenna Subject: Re: question about tunable capacitor: how to mount ?? X-Newsreader: NewsLeecher v3.0 Final (http://www.newsleecher.com) References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Lines: 13 Message-ID: X-Complaints-To: abuse@usenetserver.com X-Abuse-Info: Please be sure to forward a copy of ALL headers X-Abuse-Info: Otherwise we will be unable to process your complaint properly. NNTP-Posting-Date: Sat, 20 May 2006 11:31:52 EDT Date: Sat, 20 May 2006 15:31:52 GMT Path: news.unc.edu!canoe.uoregon.edu!newshub.sdsu.edu!nx01.iad01.newshosting.com!newshosting.com!208.49.83.154.MISMATCH!atl-c08.usenetserver.com!news.usenetserver.com!pc03.usenetserver.com!fe42.usenetserver.com.POSTED!334b1f4d!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:224534 Are you going to run QRP? I made mind out of 1/2 copper tubing and made loop from coax at the top the tuning capacitor I used was from ebay the spacing between the tuner is 1/4 inch my tuner is 4" wide 6"long and about 3 1/2 high first contact 22" off ground was Detroit Michigan I'm in Dunedin Florida second contact was Canada for about a half hour. with a small tunable cap you will have arking I am running 100 watts. Jim De W8OLD -- ---------------------------------------------- Posted with NewsLeecher v3.0 Final * Binary Usenet Leeching Made Easy * http://www.newsleecher.com/?usenet ---------------------------------------------- From JT Mon May 22 21:17:26 EDT 2006 Article: 224535 of rec.radio.amateur.antenna From: JT (jt@trek.net) Newsgroups: rec.radio.amateur.antenna Subject: Re: question about tunable capacitor: how to mount ?? X-Newsreader: NewsLeecher v3.0 Final (http://www.newsleecher.com) References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Lines: 8 Message-ID: X-Complaints-To: abuse@usenetserver.com X-Abuse-Info: Please be sure to forward a copy of ALL headers X-Abuse-Info: Otherwise we will be unable to process your complaint properly. NNTP-Posting-Date: Sat, 20 May 2006 11:37:57 EDT Date: Sat, 20 May 2006 15:37:57 GMT Path: news.unc.edu!canoe.uoregon.edu!newshub.sdsu.edu!nx01.iad01.newshosting.com!newshosting.com!208.49.83.154.MISMATCH!atl-c08.usenetserver.com!news.usenetserver.com!pc03.usenetserver.com!fe42.usenetserver.com.POSTED!334b1f4d!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:224535 Try this site www.kr1st.com.magloop.htm this one I built and am running 100 watts. 73's de Jim W8OLD -- ---------------------------------------------- Posted with NewsLeecher v3.0 Final * Binary Usenet Leeching Made Easy * http://www.newsleecher.com/?usenet ---------------------------------------------- Article: 224536 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 15:51:45 GMT Tom Donaly wrote: > The purpose of most antennas is to radiate electromagnetic waves. > That means there is loss. It also means that the current envelope is > affected. That's one of the reasons we use EZNEC. The current envelope is affected but remains a linear system function since it is the result of superposition which itself is a linear system function. > I suppose, Cecil, > that if you keep repeating the same old tired line, over and over > again, you might find someone who will agree with you. Certainly, > no antenna measurement would. The current envelope is a linear system function. I am repeating the rules and laws of mathematics. Sounds like you need to review the definition of linear systems. You can do that at: http://www.cns.nyu.edu/~david/linear-systems/linear-systems.html In particular, quoting: "Systems that satisfy both homogeneity and additivity are considered to be linear systems. These two rules, taken together, are often referred to as the principle of superposition." In general, antennas are linear systems that satisfy the principle of superposition. If they were non-linear, they would not satisfy the principle of superposition. Two linear system functions, like forward waves and reflected waves, cannot superpose to a non-linear function. Therefore, standing waves are linear, not non-linear, functions. To argue otherwise exhibits a certain degree of ignorance. Until the obvious mathematical misconception is corrected, no rational discussion is possible. To the best of my knowledge, Maxwell's equations are also linear system functions so claims of non-linearity also contradict Maxwell's equations. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224537 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 16:47:55 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Thanks for all the links which I am reading. My dipole is about 126 > > feet long which should be about right for 3.7 Mhz. I mostly use it on > > 75 M. The new feedline I have installed is a bit shorter than what I > > was using, I think it's now around 47 feet, the old stuff was 50 plus > > feet. I notice my Johnson matchbox now finds it somewhat difficult to > > tune up this antenna on 40 M so I may have to add on a few feet. > > Did you take a look at the information on my web page at: > > http://www.qsl.net/w5dxp/notuner.htm > > It tells you everything you need to know about that antenna > including why 47 feet is not the best feedline length on 40m. > In particular, the chart at: > > http://www.qsl.net/w5dxp/pnts130.gif > > shows the best lengths for 40m to be 30 feet or 92 feet. > A good compromise single length for all-HF-band operation > is 100 feet. Yes I did Cecil. I went out and remeasured and found that I have about 67 total feet of feed line now. I may shorten that up again. I'll re-check the links you provided, thanks. -- Email: dalej2@mac.com Article: 224538 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 16:55:12 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Thanks for all the links which I am reading. My dipole is about 126 > > feet long which should be about right for 3.7 Mhz. I mostly use it on > > 75 M. The new feedline I have installed is a bit shorter than what I > > was using, I think it's now around 47 feet, the old stuff was 50 plus > > feet. I notice my Johnson matchbox now finds it somewhat difficult to > > tune up this antenna on 40 M so I may have to add on a few feet. > > Did you take a look at the information on my web page at: > > http://www.qsl.net/w5dxp/notuner.htm > > It tells you everything you need to know about that antenna > including why 47 feet is not the best feedline length on 40m. > In particular, the chart at: > > http://www.qsl.net/w5dxp/pnts130.gif > > shows the best lengths for 40m to be 30 feet or 92 feet. > A good compromise single length for all-HF-band operation > is 100 feet. BTW Cecil, I could never get 100 feet of open wire in my back yard unless I coil it up or string it all over the place and that would not be good. Isn't there a shorter length that would work for 75 & 40? 73 Dale j. -- Email: dalej2@mac.com Article: 224539 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> <076dnUhaopMRoPLZRVny0Q@bt.com> Message-ID: Date: Sat, 20 May 2006 17:39:44 GMT Reg Edwards wrote: >>I suppose, Cecil, >>that if you keep repeating the same old tired line, over and over >>again, you might find someone who will agree with you. > > ========================================= > > I agreed with Cecil the first time he said it. > But I'm only a foreigner. > So whatever I say doesn't carry any weight. > Or does it? > ---- > Reg. > > You're the master of simple approximation, Reg. Cecil thinks your simplified ideas are received wisdom. Knowing you, I find it hard to believe you'd ever agree with anyone. 73, Tom Donaly, KA6RUH Article: 224540 of rec.radio.amateur.antenna From: "John, N9JG" References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Subject: Re: question about tunable capacitor: how to mount ?? Date: Sat, 20 May 2006 15:39:48 -0400 Message-ID: <4Yednd2BbdIf7fLZRVn-uQ@insightbb.com> That link doesn't "JT" wrote in message news:pJGbg.65799$w85.1909@fe42.usenetserver.com... > Try this site www.kr1st.com.magloop.htm > this one I built and am running 100 watts. 73's de Jim W8OLD > -- > ---------------------------------------------- > Posted with NewsLeecher v3.0 Final > * Binary Usenet Leeching Made Easy > * http://www.newsleecher.com/?usenet > ---------------------------------------------- > Article: 224541 of rec.radio.amateur.antenna From: "Dave" References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> <1148083790.131137.181880@j33g2000cwa.googlegroups.com> Subject: Re: FIGHT! FIGHT! FIGHT! Date: Sat, 20 May 2006 19:40:04 -0000 Message-ID: "Richard Clark" wrote in message news:s4lu62drhct2cuncrf9ti6kf1r27mle51o@4ax.com... > On Sat, 20 May 2006 12:14:29 -0000, "Dave" wrote: > >>KEEP IT GOING! > > Dave, your trolling effort is rather a poor substitute for the sense > of accomplishment. Too many do it far better, with more flair, and > offer more entertainment than this pallid use of the CAPS KEYS. I'm just cheering you on... besides if I'm going to troll I might as well abandon some other parts of decency in the process. And it doesn't seem like anyone cares, even with the obvious thread title it took off all on its own. Article: 224542 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 19:52:32 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > > Cecil Moore wrote: > >>http://www.qsl.net/w5dxp/pnts130.gif > >> > >>shows the best lengths for 40m to be 30 feet or 92 feet. > > > > Yes I did Cecil. I went out and remeasured and found that I have about > > 67 total feet of feed line now. > > (30+92)/2 = 61 feet, worst case for feeding that dipole > on 40m. For all-HF-band operation, I would highly > recommend a feedline length of 100 feet. You can use > a 60 foot run of small non-conductive rope with the > ladder-line spiraled around it and tie-wrapped to it > to obtain the better case 100 feet. Well I'll give it some thought. All I need is to find room somehow for 33 more feet of ladder. Maybe I will try it jury rigged first to see how it tunes, but not today, it rains. Doesn't the matchbox do the electrical tuning of the feedline instead of using fixed lengths as you are doing? As you said the length I have now does not tune very well on 40, I can get it to work but it's like opening a safe. I just dug out my Drake MN-2700 user manual and it says to use 135 foot long horizontal fed in the middle with 67 feet of ladder. Weird, this stuff is worse than making a pizza. Dale j. -- Email: dalej2@mac.com From Mon May 22 21:17:26 EDT 2006 Article: 224543 of rec.radio.amateur.antenna NNTP-Posting-Date: Sat, 20 May 2006 16:00:18 -0500 From: Dan Richardson <> Newsgroups: rec.radio.amateur.antenna Subject: Re: Multiband doublet feedline length Date: Sat, 20 May 2006 14:00:04 -0700 Message-ID: <7q0v62ptc4cdu3h3ce41kemo09ef8vmcc9@4ax.com> References: <2jlu62hksmq85k3fumin30cu0r627o319i@4ax.com> X-Newsreader: Forte Agent 1.93/32.576 English (American) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 20 NNTP-Posting-Host: 68.64.59.124 X-Trace: sv3-tfeNlIgfKfxFWy0UCtjTRx0wuLq9kbm0Qi1bly0959G6kT2RL3rMRRShY1nX52JlzUgrPUFhOHaB4ut!xb5S9gYROltG1NDNZ9hjFguE/AJkYsxzNWNIYaQ9hEikTsxgZinbkotEQK0PANr3xccLRWSBiwyq!o0uHHZIwRSSlG2ZRvktB X-Complaints-To: abuse@adelphia.net X-DMCA-Complaints-To: copyright@adelphia.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Path: news.unc.edu!elk.ncren.net!newsflash.concordia.ca!News.Dal.Ca!ursa-nb00s0.nbnet.nb.ca!nf3.bellglobal.com!border2.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.adelphia.com!news.adelphia.com.POSTED!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:224543 On Sat, 20 May 2006 17:57:10 GMT, Cecil Moore wrote: >Richard Clark wrote: >> There is one way to obtain a simple answer, you make the transmission >> line an odd 8th wave long which will offer reasonable tuning. This >> insight comes courtesy of Walt Maxwell's techniques offered for >> measuring steep loads found in his classic "Reflections." > >Where does Walt say that? In chapter 15. In my many years I have come to a conclusion that one useless man is a shame, two is a law firm, and three or more is a congress. - John Adams email: k6mhearrlnet http://www.k6mhe.com/ Article: 224544 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Sat, 20 May 2006 16:33:48 -0500 Message-ID: <4754-446F8B3C-20@storefull-3255.bay.webtv.net> References: <076dnUhaopMRoPLZRVny0Q@bt.com> Reg, G4FGQ wrote: "I agreed with Cecil the first time he said it. But I`m only a foreigner. So whatever I say doesn`t carry any weight. Or does it?" We all are foreigners in most places. Reg`s reputation precedes him so he always carries a lot of weight. Best regards, Richard Harrison, KB5WZI Article: 224545 of rec.radio.amateur.antenna From: ehramm@dk3uz.ampr.org (Edmund H. Ramm) Subject: Re: question about tunable capacitor: how to mount ?? References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Message-ID: Date: Sat, 20 May 2006 21:49:19 GMT In JT (jt@trek.net) writes: > [...] > I made mind out of 1/2 copper tubing > [...] You aren't possibly aka "Frankenstein"? SCNR & 73, Eddi ._._. -- e-mail: dk3uz AT darc DOT de | AMPRNET: dk3uz@db0hht.ampr.org If replying to a Usenet article, please use above e-mail address. Linux/m68k, the best U**x ever to hit an Atari! Article: 224546 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> Subject: Re: ARS License Numbers Message-ID: Date: Sat, 20 May 2006 15:15:39 -0700 > > I am quite sure that they all got their tickets with CW > > required. And the problem stations on 75 are quite the same. Which > > also proves nothing either way. > > it does prove that CW testing is at best poor proof of screening out > bad ops There's no test for one important ham skill: typing. I didn't appreciate how important it is until I learned that one of my pro-Morse buddies does all of his sending with a computer. (He can send with a key but doesn't know where his is.) He says he copies with the computer, too, although he can follow along with the audio. I asked around and found this practice is far from rare; I'm not sure "common" is the right word, though. We also might want to test for basic language skills, including punctuation. While it's not always true, the disagreeable transmissions (and NG posts) often make the speakers/writers sound pretty ignorant. Article: 224547 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: <2jlu62hksmq85k3fumin30cu0r627o319i@4ax.com> Date: Sat, 20 May 2006 22:20:04 GMT On Sat, 20 May 2006 10:53:04 -0700, Richard Clark wrote: >On Fri, 19 May 2006 21:50:35 GMT, Owen Duffy wrote: > >>Your dissapointment is perhaps caused by your expectation of a >>specific length. > >Hi Owen, > >There is one way to obtain a simple answer, you make the transmission >line an odd 8th wave long which will offer reasonable tuning. This >insight comes courtesy of Walt Maxwell's techniques offered for >measuring steep loads found in his classic "Reflections." > Richard, The original question was regarding a multiband double of unspecified length. Aren't there lengths of the dipole that in concert with an eight wave feedline would challenge the ATU? Have you made assumptions about the doublet length in making this recommendation? Owen -- Article: 224548 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> <076dnUhaopMRoPLZRVny0Q@bt.com> Message-ID: Date: Sat, 20 May 2006 22:19:31 GMT Tom Donaly wrote: > You can still pretend a dipole is a "linear system," as you > call it, and still understand that the current envelope is not > a simple sine function. Diverting to a "simple" sine function in the same spirit as diverting to a "small" loading coil? If you were always talking about a perfect sine wave, you should have said so long before now and nobody would have disagreed with you. > The Achilles heel of all your reflection > mechanics ideas is the assumption that everything is lossless. That's NOT the assumption. The assumption is that lossless systems are easiest to understand so let's understand them first before we move on to something more complex. You guys have proven that you don't even understand the simple lossless condition. > (Not to mention the fact that it's supposed to exist in outer > space.) You and Reg like to think of a dipole as a transmission line, > and Reg can even tell you its characteristic impedance (average). What > neither he nor you ever mention is the alpha part of the > propagation constant. That's the important part, though, since it > signifies radiation, the very thing the antenna was designed to do. Only about 1 dB of the steady-state energy stored in a 1/2WL dipole is radiated so radiation is not the largest effect. The radiation from an antenna can be simulated by using resistance wire to simulate a 1 dB loss in a transmission line. The reason that I have rarely mentioned such is that you guys don't understand enough of the basics to proceed to those more complex examples. > By the way, why are you quoting from a network theory book when not > too long ago you were ranting and raving about the invalidity of the > lumped constant model? The lumped constant model is valid under certain conditions. What I object to is its use under known invalid conditions. The lumped constant model and distributed network model are both *linear systems*. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224549 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 22:25:50 GMT dale.j. wrote: > Doesn't the matchbox do the > electrical tuning of the feedline instead of using fixed lengths as you > are doing? If it's a Johnson Matchbox, it has a limited tuning range. But for dipoles 1/2WL at the lowest frequency of operation, feeding in the rough vicinity of the current maximum point will work. For 80m and 40m, you might get by with 80 feet of feedline. > I just dug out my Drake MN-2700 user manual and it says to use 135 foot > long horizontal fed in the middle with 67 feet of ladder. Weird, this > stuff is worse than making a pizza. If that is for 80m or 40m, the Drake must like very high impedances. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224550 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Multiband doublet feedline length Date: Sat, 20 May 2006 17:32:39 -0500 Message-ID: <23820-446F9907-347@storefull-3252.bay.webtv.net> References: Dale j wrote: "I just dug out my Drake MN-2700 user manual and it says to use 135 fiit long horizontal fed in the middle with 67 feet of ladder." Drakes idea is probably a versatile antenna similar to the one on page 22.11 of the 2006 ARRL Handbook. At 80 meters it is about 1/2-wavelength fed with about 1/4-wavelength of feedline. A grounded radio presents a high impedance to comon-mode travel where the line meets the antenna at the resonant frequency of the antenna. Your radio should not bite you on 80 meters and a versatile tuner should make the antenna useable through 10 meters. The pattern goes through a lot of change in that range of frequencies. This is predicted by a modeling program and some of the transition is shown in the handbook. Best regards, Richard Harrison, KB5WZI Article: 224551 of rec.radio.amateur.antenna From: "Sal M. Onella" References: Subject: Re: Replacing car broadcast antenna for AM/FM/2M/70cm Message-ID: <_eNbg.27116$QP4.16428@fed1read12> Date: Sat, 20 May 2006 16:03:22 -0700 "yea right" wrote in message news:pan.2006.05.20.05.29.17.886633@spam.spam... > I am looking for a commercial antenna that I can replace the regular > broadcast antenna on my car with, that would still service the car > broadcast radio but have bandpass/bandblock filters so that I can also use > the same antenna for my mobile 2m/70cm FM radio. > > Is there such a beast? First, I couldn't find you an HF/VHF diplexer, but you can build one. http://home.datacomm.ch/hb9abx/diplhf6m-vuhf.html Second, do you have to have both radios functional simultaneously or are you willing to switch one antenna between to radios? If you're hamming you probably don't want the BCST radio playing in the background. Here's my story: Years ago, I developed an open shield in my van's BCST antenna and I didn't want to tear apart the dashboard to replace the antenna, so I put a Motorola-to-BNC adapter into the back of the car radio. From there I dropped a short length of coax down, ran it under the floormat to a point behind the seat and connected it to my MFJ magmount's coax. (If I'm hamming, I disconnect the BCST radio and use the magmount as MFJ intended. I never bothered to install a switch.) My $15.95 (last time I bought one) MFJ Dual Band magmount works perfectly as a substitute for the car's BCST antenna -- AM & FM just fine. BONUS: On long inter-city trips, I swap out the stock whip for a longer, straight whip and the BCST reception is just wonderful. Article: 224552 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 23:40:11 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Doesn't the matchbox do the > > electrical tuning of the feedline instead of using fixed lengths as you > > are doing? > > If it's a Johnson Matchbox, it has a limited tuning range. > But for dipoles 1/2WL at the lowest frequency of operation, > feeding in the rough vicinity of the current maximum point > will work. For 80m and 40m, you might get by with 80 feet > of feedline. > > > I just dug out my Drake MN-2700 user manual and it says to use 135 foot > > long horizontal fed in the middle with 67 feet of ladder. Weird, this > > stuff is worse than making a pizza. > > If that is for 80m or 40m, the Drake must like very high > impedances. I'll give the 100 ft a go and let you know. When you say wind the ladder line around a tag rope, I assume you mean to use ties around one wire of the ladder and make the loop maybe a foot in diameter or maybe 6 inches? Sort of a helix affair. Would that cause a problem with the ladder being so close to the turns? I've read where I should keep the ladder from sharp angles and away from metal objects so as not to unbalance the line and destroy the cancel properties of ladder line. The more I read about this the more it looks like black magic. Dalej. -- Email: dalej2@mac.com Article: 224553 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> <1148164087.750699.162430@i39g2000cwa.googlegroups.com> Subject: Re: ARS License Numbers Message-ID: Date: Sat, 20 May 2006 17:00:22 -0700 "an_old_friend" wrote in message news:1148164087.750699.162430@i39g2000cwa.googlegroups.com... > > We also might want to test for basic language skills, including punctuation. > why? > > why do do we want to restrict the numer of hams in that manner That's a persuasive argument and you've definitely brought some clarity to the issue. Thanks so much. Article: 224554 of rec.radio.amateur.antenna From: "CW" References: Subject: Re: Multiband doublet feedline length Message-ID: Date: Sun, 21 May 2006 00:05:35 GMT Look at his site. Cecil does not use a tuner. "dale.j. " wrote in message news:nos.pamz-7FA88A.14520920052006@news-rdr-03.rdc-kc.rr.com... >Doesn't the matchbox do the > electrical tuning of the feedline instead of using fixed lengths as you > are doing? Article: 224555 of rec.radio.amateur.antenna From: "The always Benevolent dbu." Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 00:14:50 GMT In article , "CW" wrote: > Look at his site. Cecil does not use a tuner. > > "dale.j. " wrote in message > news:nos.pamz-7FA88A.14520920052006@news-rdr-03.rdc-kc.rr.com... > >Doesn't the matchbox do the > > electrical tuning of the feedline instead of using fixed lengths as you > > are doing? Yes I have, but I think we are talking about more than one dimension. Dalej. -- Article: 224556 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> <076dnUhaopMRoPLZRVny0Q@bt.com> Message-ID: Date: Sun, 21 May 2006 00:48:42 GMT Richard Clark wrote: > On Sat, 20 May 2006 17:39:44 GMT, "Tom Donaly" > wrote: > > >>Cecil thinks your simplified ideas are received wisdom. > > > Hi Tom, > > Is there some suggestion of smoldering bush in this parable? > Commandments that are unzipped and ready for immediate entablature? > > 73's > Richard Clark, KB7QHC Hi Richard, Yes, but there's some evidence Cecil is about to apostatize. I hope he doesn't end up wandering in the wilderness. 73, Tom Donaly, KA6RUH Article: 224557 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Sun, 21 May 2006 01:12:16 GMT On Sat, 20 May 2006 16:47:55 GMT, "dale.j. " wrote: >In article , > Cecil Moore wrote: > >> dale.j. wrote: >> > Thanks for all the links which I am reading. My dipole is about 126 >> > feet long which should be about right for 3.7 Mhz. I mostly use it on >> > 75 M. The new feedline I have installed is a bit shorter than what I >> > was using, I think it's now around 47 feet, the old stuff was 50 plus >> > feet. I notice my Johnson matchbox now finds it somewhat difficult to >> > tune up this antenna on 40 M so I may have to add on a few feet. >> >> Did you take a look at the information on my web page at: >> >> http://www.qsl.net/w5dxp/notuner.htm >> >> It tells you everything you need to know about that antenna >> including why 47 feet is not the best feedline length on 40m. >> In particular, the chart at: >> >> http://www.qsl.net/w5dxp/pnts130.gif >> >> shows the best lengths for 40m to be 30 feet or 92 feet. >> A good compromise single length for all-HF-band operation >> is 100 feet. > >Yes I did Cecil. I went out and remeasured and found that I have about >67 total feet of feed line now. I may shorten that up again. I'll >re-check the links you provided, thanks. 47', now 67'... slowly more information emerges, even if changing. The following is a one band (40m) perspective of your multiband antenna. If you have a 126' dipole (as you said), it has a feedpoint impedance that is quite high around 7MHz because it is close to a full wave dipole which has a feedpoint impedance around 4200+j0 (depending on height, ground etc). A 126' dipole 15m above average ground is probably around 3600+j1400 at 7.2MHz. If you were using 67' of Wireman 551, you would expect the load seen by the tuner to be around 660-j1400 ohms (assuming an effective 1:1 balun)... which is not extreme, but it is fairly high and might challenge some ATUs. Lengthening the feedline will bring the load impedance down fairly quickly, just another 10' (ie 77' overall) gives 90-j400. Shortening the feedline a little from 67' will make it worse, 62.5' will give you the maximum load impedance of 3500+ ohms. Standing back and taking a system view, it is questionable whether making the dipole resonant or very close to resonance at 3.7MHz as you have done, makes harmonic operation easier. It certainly presents the worst case feedline VSWR on 7MHz, the highest feedline voltage (>2500V peak at 1kW), though the transmission line loss for 90' of 551 is only 0.6dB in the above scenario. Owen PS: I know conventional wisdom is to make a multiband dipole half wavelength at the lowest operating frequency, and the ARRL shows such an antenna with 130' dipole length. It turns out that if a dipole with practical length of open wire feeder to an ATU at the tx is less than about 35% of a wavelength, system losses increase dramatically with reduced length, so the dipole should not be less than about 35% of wavelength at the lowest frequency. You can see the effect in Fig 2 of my article at http://www.vk1od.net/LOLL/index.htm . In that case, the system losses with a 66' dipole are acceptable down to about 5.5MHz, for 3.5MHz the dipole needs to be greater than 5.5/3.5*66' or 103'. -- Article: 224558 of rec.radio.amateur.antenna Message-ID: <446FD707.D3B5E8CD@shaw.ca> From: Irv Finkleman Subject: Re: question about tunable capacitor: how to mount ?? References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Date: Sun, 21 May 2006 02:56:52 GMT "jt@trek.net" wrote: > > Try this site www.kr1st.com.magloop.htm > this one I built and am running 100 watts. 73's de Jim W8OLD > -- > ---------------------------------------------- > Posted with NewsLeecher v3.0 Final > * Binary Usenet Leeching Made Easy > * http://www.newsleecher.com/?usenet > ---------------------------------------------- The link should read http://www.kr1st.com/magloop.htm Irv VE6BP -- -------------------------------------- Diagnosed Type II Diabetes March 5 2001 Beating it with diet and exercise! 297/215/210 (to be revised lower) 58"/43"(!)/44" (already lower too!) -------------------------------------- Visit my HomePage at http://members.shaw.ca/finkirv/index.html Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada Article: 224559 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Sat, 20 May 2006 22:46:42 -0500 Message-ID: <21360-446FE2A2-1481@storefull-3257.bay.webtv.net> References: Mike, W4EF wrote: "I would agree, Richard, but at HF frequencies, the current path around the shield isn`t real;ly broken by the gap." To best describe what broken means, a picture helps. There is a picture on page 13.18 of the 2006 ARRL Handbook. Fig 13.26 has a legend which says: "To prevent shielding of the loop from magnetic fields, leave the shield unconnected at one end." I think the handbook has it right. Best regards, Richard Harrison, KB5WZI Article: 224560 of rec.radio.amateur.antenna Subject: Auto-Tuners with balanced antenna? From: Ed Message-ID: Date: 21 May 2006 04:12:31 GMT Any recommendations for an automatic tuner that will work well with balanced antennas fed with 600 ohm ladder line? Specifically, I have in mind a 160M dipole fed with ladder line. Ed K7AAT Article: 224561 of rec.radio.amateur.antenna From: m II Subject: Re: HF broadcasting antennas References: <5s84k3-2id.ln1@remote.clifto.com> Message-ID: Date: Sun, 21 May 2006 04:25:44 GMT clifto wrote: > sipa wrote: > >>First please excuse me for my bad english. > > > 1. Your English is far better than my Hungarian. Mindenkinek a Magyarja job mint az Angolod.. mihaly (Doing the Dance of Joy..) II Article: 224562 of rec.radio.amateur.antenna From: m II Subject: Re: HF broadcasting antennas References: <5s84k3-2id.ln1@remote.clifto.com> Message-ID: Date: Sun, 21 May 2006 04:27:54 GMT m II wrote: > clifto wrote: > > >>sipa wrote: >> >> >>>First please excuse me for my bad english. >> >> >>1. Your English is far better than my Hungarian. The poster's .sig was a Slavic language, not Hungarian. mike Article: 224563 of rec.radio.amateur.antenna Subject: Re: Auto-Tuners with balanced antenna? From: Dave Oldridge References: Message-ID: Date: Sun, 21 May 2006 06:53:58 GMT Ed wrote in news:Xns97C9D7E3CBC77spectrumhogstarbandn@198.186.192.196: > > Any recommendations for an automatic tuner that will work well with > balanced antennas fed with 600 ohm ladder line? > > Specifically, I have in mind a 160M dipole fed with ladder line. Well, I've not tried THAT, specifically, but my MFJ939B will load a 50foot piece of what looks like 200 or 150 ohm twinlead with half of one side stripped away just fine, if I connect up the internal balun. And I mean LOAD it--on any frequency from 1.8 to 30mhz. I've also loaded small loops with it well off their resonant points and use it all the time to lead hamstick whips well off their resonant points. I don't think you'd have any real trouble as long as the 600 ohm line ran straight away from the antenna, at least in the near field. -- Dave Oldridge+ ICQ 1800667 Article: 224564 of rec.radio.amateur.antenna From: KC1DI Subject: Re: Auto-Tuners with balanced antenna? Date: Sun, 21 May 2006 08:41:18 -0400 Message-ID: References: Ed wrote: > Any recommendations for an automatic tuner that will work well with > balanced antennas fed with 600 ohm ladder line? > > Specifically, I have in mind a 160M dipole fed with ladder line. > > > Ed K7AAT I use the LDG z100 with and external Balun Works well for me. 73 Dave kc1di Article: 224565 of rec.radio.amateur.antenna From: "Lew" References: Subject: Re: Auto-Tuners with balanced antenna? Message-ID: Date: Sun, 21 May 2006 09:01:24 -0400 I run a SGC ATU to my Dipole with ladder line with no problems Lew "KC1DI" wrote in message news:e4pn0l$f4h$1@emma.aioe.org... > Ed wrote: >> Any recommendations for an automatic tuner that will work well with >> balanced antennas fed with 600 ohm ladder line? >> >> Specifically, I have in mind a 160M dipole fed with ladder line. >> >> >> Ed K7AAT > > > I use the LDG z100 with and external Balun Works well for me. > 73 Dave kc1di Article: 224566 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Multiband doublet feedline length Message-ID: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> References: Date: Sun, 21 May 2006 13:22:18 GMT On Tue, 16 May 2006 22:55:13 GMT, "dale.j. " wrote: >What is the correct way to determine the non-resonant feedline length of >a multiband doublet using 450 ohm open wire. > > tnx >Dale I have a 130 foot dipole, about 25' high in the middle, 20' at the ends, fed with 47' of the Wireman's ladderline, going directly to the 4-1 balun of an old mfj989c tuner. From everything I've read in this thread, it shouldn't tune worth a darn on 40 meters, but I can get a 1-1 swr match on 40, as well as every other band. I guess all you can do is put it up and see if it works :-) One of these days I might try Cecil's idea, a 100 foot feed of ladderline, but I'd have to string about 50' of that back and forth to make it work. bob k5qwg Article: 224567 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 13:43:59 GMT dale.j. wrote: > I'll give the 100 ft a go and let you know. > > When you say wind the ladder line around a tag rope, I assume you mean > to use ties around one wire of the ladder and make the loop maybe a foot > in diameter or maybe 6 inches? Sort of a helix affair. Would that > cause a problem with the ladder being so close to the turns? You are forming 100 ft. of ladder-line into a 50 ft. long helix. The spacing on the turns will not be a problem as it will be a very loosely wound helix. Tie a knot in the messenger string every 10 inches. Anchor one point of the ladder-line to a knot in the messenger string using black tie-wraps. Take 20 inches of ladder-line and anchor it at the next knot down from the first knot. That will give you one turn of the helix. Repeat until you have a 100 foot feedline. If you didn't want to use tie-wraps, you could tie the 10 inch spaced knots through the ladder-line every 20 inches of ladder-line. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224568 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 13:49:14 GMT CW wrote: > Look at his site. Cecil does not use a tuner. > > "dale.j. " wrote: >>Doesn't the matchbox do the electrical tuning of the >> feedline instead of using fixed lengths as you >>are doing? When I was using an ICOM-706, I didn't use a tuner. Now that I have an ICOM-756PRO, I choose a feedline length that resonates the antenna system in the center of a band and then use the autotuner for excursions toward band edges. Making the feedline a fixed length of 100 ft. and then using a tuner is somewhat similar to what I am doing now. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224569 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 13:55:24 GMT Owen Duffy wrote: > It turns out that if a dipole with practical length of open wire > feeder to an ATU at the tx is less than about 35% of a wavelength, > system losses increase dramatically with reduced length, so the dipole > should not be less than about 35% of wavelength at the lowest > frequency. Agrees pretty closely with Walter Maxwell's 3/8 wavelength minimum dipole advice. > You can see the effect in Fig 2 of my article at > http://www.vk1od.net/LOLL/index.htm . In that case, the system losses > with a 66' dipole are acceptable down to about 5.5MHz, for 3.5MHz the > dipole needs to be greater than 5.5/3.5*66' or 103'. Agrees pretty closely with the length of a G5RV. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224570 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT? Here is another W8JI myth bone! References: <21360-446FE2A2-1481@storefull-3257.bay.webtv.net> <9f6dndFM6YCPt-3ZRVn-rQ@comcast.com> <1148204558.861148.41500@j55g2000cwa.googlegroups.com> Message-ID: Date: Sun, 21 May 2006 14:06:07 GMT w8ji@akorn.net wrote: > Absolutely nothing, neither electic nor magnetic, couplesthrough the > wall of a conductor more than several skin depths thick. Do 60 Hz magnetic fields penetrate RF coax since the conductor is not more than several skin depths thick? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224571 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Auto-Tuners with balanced antenna? References: Message-ID: Date: Sun, 21 May 2006 14:08:10 GMT Lew wrote: > I run a SGC ATU to my Dipole with ladder line with no problems Isn't that contrary to SGC's recommendations? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224572 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> Message-ID: Date: Sun, 21 May 2006 14:12:34 GMT Bob Miller wrote: > I have a 130 foot dipole, about 25' high in the middle, 20' at the > ends, fed with 47' of the Wireman's ladderline, going directly to the > 4-1 balun of an old mfj989c tuner. From everything I've read in this > thread, it shouldn't tune worth a darn on 40 meters, but I can get a > 1-1 swr match on 40, as well as every other band. That "1-1 swr" is on the coax between the tuner and the transmitter. The SWR on the ladder-line is probably around 12:1. > One of these days I might try Cecil's idea, a 100 foot feed of > ladderline, but I'd have to string about 50' of that back and forth to > make it work. Please see my other posting. Using a messenger string, tie wrap 20 inches of ladder-line to every 10 inches of string. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224573 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 15:02:48 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Doesn't the matchbox do the > > electrical tuning of the feedline instead of using fixed lengths as you > > are doing? > > If it's a Johnson Matchbox, it has a limited tuning range. > But for dipoles 1/2WL at the lowest frequency of operation, > feeding in the rough vicinity of the current maximum point > will work. For 80m and 40m, you might get by with 80 feet > of feedline. > > > I just dug out my Drake MN-2700 user manual and it says to use 135 foot > > long horizontal fed in the middle with 67 feet of ladder. Weird, this > > stuff is worse than making a pizza. > > If that is for 80m or 40m, the Drake must like very high > impedances. I just tacked on additional ladder line for a total of 91 feet, it's draped all over the place. The matchbox tunes more difficult on 75 M but tuned right up on 40. The matchbox controls are skewed quite a ways off the center point. tuning control is at 26 and match is about 15 so it does not seem to like this length any better. I could tack on another 15 feet but then I'd have to lay it on the ground which is not good. I could shorten up the original 67 feet to perhaps 50 plus but that would make it worse? The Drake MN2700 uses a 4 to 1 balun for matching ladder line. I use my Johnson KW matchbox for the ladder line. -- Email: dalej2@mac.com Article: 224574 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: 2.4 GHz Yagi References: <1148186964.790355.140740@i39g2000cwa.googlegroups.com> Message-ID: Date: Sun, 21 May 2006 09:40:14 -0500 I'd suggest it isnt worth attempting. The frequency change is more than 3:1 from the original TV use. There are a lot of simple 2.4GHz designs out there that are worth looking at. Cheers Bob VK2YQA pdrunen@aol.com wrote: > > Hi Group, > > I looking at convering a TV UHF antenna to 2.4 GHz, the antenna has a > yagi part with elements spaced every 3 inches and the elements are the > same lenght of about 3 inches. Article: 224575 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Multiband doublet feedline length Message-ID: References: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> Date: Sun, 21 May 2006 15:58:25 GMT On Sun, 21 May 2006 14:12:34 GMT, Cecil Moore wrote: >Bob Miller wrote: >> I have a 130 foot dipole, about 25' high in the middle, 20' at the >> ends, fed with 47' of the Wireman's ladderline, going directly to the >> 4-1 balun of an old mfj989c tuner. From everything I've read in this >> thread, it shouldn't tune worth a darn on 40 meters, but I can get a >> 1-1 swr match on 40, as well as every other band. > >That "1-1 swr" is on the coax between the tuner and the >transmitter. The SWR on the ladder-line is probably around 12:1. > >> One of these days I might try Cecil's idea, a 100 foot feed of >> ladderline, but I'd have to string about 50' of that back and forth to >> make it work. > >Please see my other posting. Using a messenger string, tie >wrap 20 inches of ladder-line to every 10 inches of string. If I were to use W7FG's 600-ohm line, would 100' still be a good length? bob k5qwg Article: 224576 of rec.radio.amateur.antenna From: "RST Engineering" References: <1148186964.790355.140740@i39g2000cwa.googlegroups.com> Subject: Re: 2.4 GHz Yagi Date: Sun, 21 May 2006 09:21:52 -0700 Message-ID: Is there a URL where this is discussed? Jim And, a small satellite TV dish is easy to convert to 2.4 > GHz. > > Jerry > Article: 224577 of rec.radio.amateur.antenna From: Me Subject: Re: Auto-Tuners with balanced antenna? References: Message-ID: Date: Sun, 21 May 2006 18:07:22 GMT In article , Cecil Moore wrote: > Lew wrote: > > I run a SGC ATU to my Dipole with ladder line with no problems > > Isn't that contrary to SGC's recommendations? Only if you believe that SGC, has a CLUE about how their autotuner works, and the design of the firmware that runs it............. Me Article: 224578 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> Message-ID: Date: Sun, 21 May 2006 18:32:24 GMT Bob Miller wrote: > If I were to use W7FG's 600-ohm line, would 100' still be a good > length? I don't know. If you have EZNEC, it can tell you. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224579 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 19:54:36 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > I'll give the 100 ft a go and let you know. > > > > When you say wind the ladder line around a tag rope, I assume you mean > > to use ties around one wire of the ladder and make the loop maybe a foot > > in diameter or maybe 6 inches? Sort of a helix affair. Would that > > cause a problem with the ladder being so close to the turns? > > You are forming 100 ft. of ladder-line into a 50 ft. long helix. > The spacing on the turns will not be a problem as it will be > a very loosely wound helix. Tie a knot in the messenger string > every 10 inches. Anchor one point of the ladder-line to a knot > in the messenger string using black tie-wraps. Take 20 inches of > ladder-line and anchor it at the next knot down from the first knot. > That will give you one turn of the helix. Repeat until you have > a 100 foot feedline. If you didn't want to use tie-wraps, you > could tie the 10 inch spaced knots through the ladder-line every > 20 inches of ladder-line. I just dug out my Practical Wire Antennas book by John Heys, G3BDQ, RSGB 1989, P. 16 & 17 "centre-fed antennas using tuned feedlines", and it collaborates the information in my old ARRL 1960 handbook which says to calculate one half of the horizontal wire plus the feedline length and that total number should not equal certain critical lengths one of which is 160 feet on 3.6 Mhz, there are more. I hate to beat this to death, but frankly I don't think any of us has a clear understanding of this antenna. Dalej. -- Email: dalej2@mac.com Article: 224580 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: