[ARC5] W5SUM Discovers SCR-274N Mystery

[Mark K3MSB]

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/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?
>>
>
>
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