Subject: GLOWBUGS digest 43

From: [email-masked]
Date: Sat, 9 Dec 1995 20:48:37 -0600 (CST)

GLOWBUGS Digest 43

Topics covered in this issue include:

  1) Two Tube Superhet Receiver
	by [email-masked]
  2) Re: Two Tube Superhet Receiver
	by "James P. Rybak" <[email-masked]>
  3) inrush current
	by Bruce Robertson <[email-masked]>

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Date: Sat, 9 Dec 1995 02:57:46 -0500
From: [email-masked]
To: [email-masked]
Subject: Two Tube Superhet Receiver
Message-ID: <[email-masked]>

Thanks to all who responded to my call for two tube receiver ideas.  During
my search for an appealing circuit, I came across a design in the 1948 ARRL
Handbook called the Two Tube Superhetrodyne Receiver.  The circuit uses a 6K8
converter tube to mix the desired range down to a 1600 KHz IF.  The second
tube, a 6SN7 dual triode, is used as a regenerative detector and audio amp.

I am wondering if anybody has any experience with this circuit?  In theory it
sounds good since selectivity is better achieved at a lower frequency.  On
the other hand, I would imagine that oscillator stability would become an
issue, especially above 5 MHz.

A second question is, Does anybody know where I might find the specified coil
forms?  The form is a shielded, plug in, slug tuned form #74001 from Millen.
 I was fortunate enough to have two of these forms in my junk box but, that
only gets me onto one band.

73's,   Eric WD6DGX

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Date: Sat, 9 Dec 1995 12:01:24 -0700 (MST)
From: "James P. Rybak" <[email-masked]>
To: [email-masked]
Cc: Multiple recipients of list <[email-masked]>
Subject: Re: Two Tube Superhet Receiver
Message-ID: <[email-masked]>

I, too, have been interested in building the two-tube superhet shown in 
the 1948 handbook for some time.  The only thing holding me back, as 
well, are the Millen 74001 coil forms and shields.  I'd sure appreciate 
it if someone could suggest an alternative approach to those coils.

Jim Rybak  W0KSD

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Date: Sat, 9 Dec 1995 17:23:28 -0500 (EST)
From: Bruce Robertson <[email-masked]>
To: Multiple recipients of list <[email-masked]>
Subject: inrush current
Message-ID: <[email-masked]>

I noticed in my 1953 ARRL Handbook that hollow rectifiers are rated with 
max current, but no inrush current which is the bugaboo for silicon 
diodes (i.e. the current that comes when the rig is turned on and the 
filter caps give basically a dead short for a millisecond). Thinking 
about this, I figure that hollow rectifiers slowly come on line as the 
filament heats up, so this isn't a problem. Am I right?

73, VE3UWL

Bruce G. Robertson  Dept. of Classics, U. of T.     

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End of GLOWBUGS Digest 43
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