[ARC5] W5SUM Discovers SCR-274N Mystery

[WA5CAB at cs.com]

That would make sense with the four different models listed.  Probably the 
best guess, although I don't think that I ever saw an FT-243 that low in 
frequency.  But I have never opened up a 100 KC holder to see how large the 
plate is.

WA5CAB

In a message dated 06/24/2017 08:23:35 AM Central Daylight Time, 
arc5 at mailman.qth.net writes: ac2eu at yahoo.com
> My guess is since it was for several different models, it may have 
> originally been a 100 KHZ crystal for calibrating the dial tick marks?
> God only knows why the ham did what he did to it!
> 
> On Friday, June 23, 2017 10:16 PM, Mark K3MSB <mark.k3msb at gmail.com> 
> wrote:
> 
> 
> 
> I wouldn't think professionals would build devices and label them only to 
> drive a screw through said labeling as part of production.
> 
> I think the cap and screw were "aftermarket", but not necessarily by a 
> ham.  Even today in our development and lab areas at work if we need a gizmo 
> we make it with what's on hand.  Neccessity is the mother of invention.....
> 
> 
> Mark K3MSB
> 
> 
> On Jun 23, 2017 1:09 PM, "Michael Hanz" <aaf-radio-1 at aafradio.org> wrote:
> >> I suspect we are seeing two things at work.  The first is a 
>> modification made by professionals, the second made by a ham who installed the button 
>> capacitor.  Note how he chipped the phenolic and drilled right through 
>> the nice engraving.  I am only speculating, but one possibility might be the 
>> Lockheed Aircraft Service 274N crystal modification introduced in 1947.  
>> Drawing attached.  This drawing only mentions the BC-696-A and BC-458-A, 
>> but there would be no reason why it could not have been later expanded to 
>> all four 274N transmitter types.
>> 
>> I had to resample the drawing to get it under the attachment size for 
>> this reflector, but I'll send the original 3500 pixel wide drawing to anyone 
>> who wants it, or put it in the docs section of my aafradio webpage if 
>> there is enough interest.
>> 
>>          73,
>>  - Mike  KC4TOS
>> 
>> On 6/23/2017 11:47 AM, David Stinson wrote:
>> >>> 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/2ScqwpTX rHxNT6ZY7
>>> 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/fSKufUSF bpwogPD86
>>> 
>>> Things get interesting when you turn the crystal holder over:
>>> https://goo.gl/photos/4cZDarBP GCT3Pjsp9
>>> 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?
>>> 
>> 
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