Subject: GLOWBUGS digest 460

From: [email-masked]
Date: Fri, 28 Feb 1997 19:03:30 -0600 (CST)

GLOWBUGS Digest 460

Topics covered in this issue include:

  1) Re: regen headphone useage
	by [email-masked] (Tom R. Rice)
  2) Re: Neat WELL BUILT classic regen receiver design found finally
	by [email-masked]
  3) Re: More Regenerator Musings.....
	by [email-masked]

----------------------------------------------------------------------

Date: Thu, 27 Feb 1997 18:07:19 -0800 (PST)
From: [email-masked] (Tom R. Rice)
To: [email-masked] (glowbugs)
Subject: Re: regen headphone useage
Message-ID: <[email-masked]>

> transformer-coupled audio output amps .... with the phones in series with
> the HV supply and the plate of the audio tube I feel a lot better with 45 or
> 90 volts in there versus 250 volts going around my noggin! 

	You know, I've wondered about that practice of putting
	the cans in series with the B+.  I have a precious pair
	of Trimm Featherweights which come from that era.

	What bothers me is that I would expect the cans to be 
	gradually de-magnetized as the connection was made and
	broken, especially if the DC flow was opposite to the
	direction of flow which would act to enhance the strength 
	of the permanent magnets in the headset. 

	I seem to remember that Elmer Osterhoudt (Modern Radio
	Labs) published a pamphlet on re-magnetizing your cans.

	Comments invited;  in the meantime, it's always a
	coupling condenser or output xfmr for me!   

	73 de WB6BYH      

-- 
"Start off every day with a smile and get it over with."  --W.C.Fields
Tom R. Rice  
[email-masked]     
CIS: 71160,1122       

------------------------------

Date: Wed, 26 Feb 1997 17:22:29 -0500 (EST)
From: [email-masked]
To: [email-masked] (Sandy W5TVW)
Cc: [email-masked] ()
Subject: Re: Neat WELL BUILT classic regen receiver design found finally
Message-ID: <[email-masked]>

> Limiting the set to two bottles, I have a tendency to try the 6U8/6EA8.
> Pentode RF amp/triode detector, triode AF amp/pentode output stage.
> The 6U8 pentode should be easily capable of low power loudspeaker
> operation at about 1/2 watt out or so like the 6AK6/6G6G.

That is a very good idea.  Four bottles for the price of two.
Find out what is the most common of the lot in terms of basing diagrams,
and then use that as a generic form.

> Limited to only one COMMON tube type, then I'd say the 6BA6.  Triode
> connected even, if you want a triode detector.  They are plentiful as
> everything!  I ordered some 6186/6AG5's at .08 each lately.  Curious to see
> what they will do!

Gee, I can't find them around here that commonly.  Where were you getting
them at 8 pfennigs each?  At that price, I could stand a hundred maybe
for generic play, although I prefer octals because you can still get
the sockets down at the generic refridgeration/industrial supply as
octal relay sockets ---- pretty good for breadboarding use.

> I prefer triode detectors.  They seem to have easier to control
> characteristics and  don't overload as easy as tetrodes/pentodes.  In my
> '32, '32, '30 SW-3, I have found that the '32 is quite microphonic.  The '34
> seems better.  The 1A4P is better yet and seems to perform better on 20
> meters.  They are all poor above 15 mhz.  I do remember when I had an ACSW-3
> (which I traded off stupidly in my high school days!)

I like triodes, and the best I have found is the 76, with the 27 as a close
second.  The 56 would be next and then they all are about equal after that.

> The best combo was a pair of 6D6's and a '76 audio stage.  The 6D6 even
> worked pretty well with the 10 meter bandspread coil set I had!

6D6/6C6s are good in detector service.  The 76 has always been a strong
audio tube, but the 6SN7 is not half bad.

> On the "audio reactor"......the BC-221 has a very nice Stancor 250
> Henry choke in it!  I usually buy "junker" BC-221's just to salvage for
> parts!  (Don't tell the purists
> on the BA reflector about this!  They'd strip a gear!).

Of course, I won't.  I have picked up several odd chokes that way,
and that is fine.  The LM choke is only a few henries tho.

>  In fact, I'd
> wondered about using the BC-221 chassis as the basis for a regenny receiver
> since the main tuning cap
> has a very slow ratio.  Discarding the existing coils of course and going to
> plug-in ones.  I have given up on the idea of trying to make the RF and
> detector tanks "track"
> as on the ham bands, this is really an exercise in futility.  In that I would
> have a tendency to go 6K7 or 6SK7 RF, 6SN7 det/1st audio, 6G6G audio out.

It would do nicely.  I was thinking of the same thing on the chassis of the
last gasp of the BC-221 (AN/URM-32).  I got one for 3 bucks recently and
was trying to make a vfo out of it -- not enuf oompf, but it would make
a nice regen detector deck, with room to spare.

> 73,
> E. V. Sandy Blaize, W5TVW

Fire up on 160M tonight at about 11-12pm your time.  I would guess after
the late news......

73/ZUT DE NA4G/Bob UP

------------------------------

Date: Fri, 28 Feb 1997 15:46:15 -0500 (EST)
From: [email-masked]
To: [email-masked]
Cc: [email-masked] (), [email-masked]
Subject: Re: More Regenerator Musings.....
Message-ID: <[email-masked]>

> Bob;
> Greetings from a wet and windy Hawaiian island.  Ive been following the
> Regen thread with great interest for several weeks now.  Forgive my
> ignorance but what is this golden thread RAL receiver you folks elude to
> from time to time?  Please point me in the right schematic direction. 

Greetings, matey!  The RAL schematics are in the BA archives at
ftp.theporch.com/pub/mailing-lists/boatanchors/ral*.*.  The schematic
and spare dial card images are there.  Someday, I hope to get the manual
online there, also.

The RAL is the best of the commercial/military regenerative receivers.
It was designed and built by RCA for the Navy starting about 1936 on
throughout WWII.  It was used on vessels until the Cuban Missile Crisis
and later, particularly diesel subs and destroyers and the like (lesser
vessels mostly, although they were carried in secondary installations aboard
battleships, etc.).  It has two stages of tuned RF, a pentode detector,
two stages of audio, and audio derived AGC, plus the finest audio filters
ever put into a receiver of the tube era.  The filters are passband at
1400hz plus tuneable peaked at any frequency from about 300 to 1350 hz.
The selectivity is such that without filters, it will pass about 2khz
maximum and with the filters it passes about a 200 cycle peak tuned
wherever you want it.  Most folks consider it a dawg, but I have been
using it every day for over 20 years, and it puts modern rigs to shame,
until you get to the R-388 and R-390 class gear.  Modern sandystate gear
may be more sensitive, but not any better on CW, and they tend to be
very prone to overloading from nearby sigs.  The RAL handles this much
better than most receivers, until you get R-390 class.  Alas, the dial is
nil, with only a 0-1000 logging scale.  It is heavy, the ugliest thing since
spark sets, but for me it runs like a striped arsed ape.  It is not that
bad on CW contests even, but is a 5 handed operation to tune quickly.
I consider it a true BA sleeper, with a niche for the diehard CW folks. 
It receives sideband quite well, but clips the sidebands off of AM (like
listening to AM through a 1.5khz ssb filter.

There ought to be at least a couple of dozen RAL's around the island
hams there that you could get your hands on, would be my guess, if you
checked around some.  Mostly they sit in the sheds, garages and attics.

> IMHO, the hardest thing to incorporate the (quite) 1S4/1U4/3S4 etc...
> pentodes into the prolification of seperate indirectly heated cathode
> tube type circuits is the lack of specifics on biasing the negative
> heater pin (usually pine 1) so that it can be used as a cathode.  More
> uncertanty, Pin 1 is (in most cases) internally attached to the screen
> grid #3 and is available at pin #5.  Typical tube geomitry seems to
> indicate that now the raised (biased) cathode is also nearer to the
> plate and not the control grid #1.  Understanding of coarse, that pin 7
> is the usual A+.  All I have gleened out of all I have read to address
> this design idea is to bring the -B into the chassie with an insulated
> point that in turn is shunted to chassie ground with a noninductive low
> value (what value?) resistor.  Then run a seperate combined A-, B- bus
> from the unchassie grounded point of the shunt resistor to all the pin
> #1s on all the tubes.  Perhaps a 2.7k variable resistor in series with a
> say 270 ohm fixed (limiting) resistor to chassie ground as a means to
> adjust the hot filment cathode bias value shunt.

Well, you really don't need to bias the typical regenerative detectors
using these tubes.  At lower voltages, you don't even need to bias the
audio.  At maxed voltages (90vdc) you might use some C- bias on the
audio stages, if you got out of hand distortion.  Typically, for your
ECO application, which is what that thing is --- J.B. Dow's Electron
Coupled Oscillator from about 1930 --- Proc. I.R.E, and QST about 1932
or 1933 or so, the common thing to do is to float the filaments up from
ground via RF chokes and couple to the coil tap using a low impedance
capacitor (typically 0.001 or 0.01ufd), OR, wind the filament lines
bifillarly up to the tap to raise them above RF ground (the best way
to do it, and the way Dow did it best, and the messiest way to do
for regen plugin coils).  That is the best way to handle the problem
of a cathode tap up from rf ground.  Alternatively, you can ground
the cathode and use the low side of ground as the tickler connection
to the screen grid, to complete the oscillatory circuit.  This is
easier to do, but the first way is ``supposed'' to work better (I dunno,
since I don't use battery tubes in ECO circuits although I have this
803 I have been saving for a Dow ECO glowbug transmitter at about 50
watts input.....(:+}}.....).

>  The reason for all
> this band width is because I found that the best regen feed back scheme,
> is where we use a low point inductive tap on the L in the LC tuned
> circuit.  A second tap placed a few turns above this point also clears
> up the scrunched up band spread.  I can't take any credit for this later
> design reasoning for it is well defined in an artical by David Newkirk
> WJ1Z in QST Sept 1992 Pg.35 through 39. And it works.  Only I sure would
> like to use those LV Htr. tubes.  With 4 (3S4s), were only looking at
> 200 mA.  What say Bob and you other glowbug buffs with simular mind bent
> experience. Tnx es Aloha , Peter, KH6CTQ

The design dates from the 1930's and is directly traceable to Dow's
ECO designs using 50 watt tubes.  Well, try it, but for the first
iteration I would try the tap at RF ground and raise the screen grid
up from ground (suitably choked and/or bypassed) and use the low side
of the tap as the RF tickler point.  If you are a real diehard, try
Dow's original circuit.

LV heater tubes work fine.  I prefer indirectly heated types for serious
work and triodes for fun filamentary work (although my 1925  2-tuber has
been holding its own with the best of them on 160M lately, even on an
indoor antenna 10 feet long!).  Triodes are a lot less finicky, and even
make great RF stages if you don't pressure them so hard they go into
oscillation.

What say......``GO FOR IT!''

73/ZUT DE NA4G/Bob UP

You and ol' Jeffer ougtta get together since you are both out on the
island (great for a ground system .....(:+}}...., just watch out for
flowing lava, tourists, and great whites, right?  Where are all the
RAL's these days, out there?.....(:+}}.....).

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End of GLOWBUGS Digest 460
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