[ARC5] W5SUM Discovers SCR-274N Mystery

[Mike Everette]

It is definitely a doo-able to plug an FT-243 into the crystal socket -- offhand I forget which pins you use -- to sub for a missing calibration crystal.  I've done this numerous times, one that comes to mind is to use a 7000 kc rock intended for a BC-659 into a 5.3-7 or 7-9.1 transmitter to use as a 40 meter band edge marker.  And it is remarkably close to being right on (at least the one I used turned out to be).
When I first saw Dave's original message I wondered if it might be either a "universal" cal crystal, like a 1 mc unit, or perhaps a mil-mod to crystal-control the radio as was done with some BC-230 transmitters on 4495 kc tower frequencies.  Either way, I'm interested in how this thread plays out.
73
Mike
WA4DLF

      From: WA5CAB--- via ARC5 <arc5 at mailman.qth.net>
 To: arc5 at mailman.qth.net 
 Sent: Friday, June 23, 2017 7:37 PM
 Subject: Re: [ARC5] W5SUM Discovers SCR-274N Mystery
   
I've often wondered whether or not anyone had ever tried to substitute an FT-243 for a DC-8.  But if that's what this was originally, I agree that it doesn't make much sense that it is marked for all four of the HF transmitters that the AAF bought.

In a message dated 06/23/2017 10:48:07 AM Central Daylight Time, arc5 at ix.netcom.com writes: 

After all these years, I thought I had seen
everything one could see concerning SCR-274N,
but Ronnie, W5SUM, has discovered something
intriguing.  

Ronnie acquired a ham-modded BC-696.
https://goo.gl/photos/2ScqwpTXrHxNT6ZY7
Rattling-around the inside was an interesting
artifact:  an FT-243 crystal holder with its face
and internals removed, a "button" capacitor 
installed inside and a WWII-era plastic "handle"
attached:
https://goo.gl/photos/fSKufUSFbpwogPD86

Things get interesting when you turn the crystal 
holder over:
https://goo.gl/photos/4cZDarBPGCT3Pjsp9
Engraved on the back:
FOR USE IN RADIO TRANS.
BC-457
BC-458
BC-459
BC-696

Were this some kind of  "calibration crystal"
for the eye tube which a ham gutted,
one would expect the Signal Corps to order 
them with markings for the corresponding 
transmitter to avoid confusion,
not for all of them.  The polymer used for
the "handle" seems much older than something
used by a 1950s ham and its decay matches
period materials.

Ronnie is kindly sending me the transmitter and
the artifact, hoping that he and I may be able to 
tell ham mods from any possible Signal Corps mods.

Any ideas or discussion on the possible use
of this surprising bit?

TNX OM DE Dave AB5S


Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
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