[ARC5] "Using Defective Crystals" 1937

[Fuqua, William]

I assume the crystal is in an oscillator circuit already, the oscillation is maintained in normal operation by regeneration or positive feedback. With circuit as shown L1 only changes loading reactance. The other coil outside of the dashed lines is part of the grid bias circuit, RF choke and grid resistor.
  The only source for regeneration is coupling to L1 from unshielded tank inductor in the plate circuit. which was probably in 1937 another vertical plug in coil.

73
Bill wa4lav

________________________________
From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> on behalf of J Mcvey via ARC5 <arc5 at mailman.qth.net>
Sent: Sunday, June 21, 2020 10:08 PM
To: milsurplus listserv <milsurplus at mailman.qth.net>; Glowbugs <tetrode at googlegroups.com>; ARC-5 Maillist <arc5 at mailman.qth.net>; Hubert Miller <Kargo_cult at msn.com>
Subject: Re: [ARC5] "Using Defective Crystals" 1937

CAUTION: External Sender


I've heard of "gimmick capacitors", so I guess we can call this a "gimmick coil"?
It's installed on top of the chassis , so it interacts with the tube., I suppose...

I've had some 1930's radios tend to oscillate if I left a tube shield off . Perhaps he is using that phenomena to enhance the crystal?  Just a W.A.G. on my part, but it probably worked.
It was worth a whole $5 back in the day!


On Sunday, June 21, 2020, 8:07:36 PM EDT, Hubert Miller <kargo_cult at msn.com> wrote:



Crystals seem to be a popular topic among radio communication hobbyists.

Herewith an item from ' Short Wave and Television ' magazine, Dec. 1937.

I have to admit, I do not understand how the added coil would work to increase

feedback gain. It does not appear to be coupled in any way to an output inductor.

( There are a number of crazy, fascinating, and instructive kinks hiding in the old

magazines. )

-Hue Miller



[cid:R8eCYahS5MW2fP0V7EOe]

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