[MRCA] BC-654 Crystal Question

[Robert Downs]

The FT-241 holder fits an octal socket.  So duplicating the original adapter would be simple. If you start with the circlip retained type socket.  Might have to turn down part of the octal to fit into the 5-pin base.  The transmitter schematic shows which contacts are used in the 5-pin but not which two are used in the octal.  And the SIG 5 entry for 2Z262 doesn’t either.  

 

The crystals inside the FT-241 are already about 1/4 the size of the ones inside the FT-243.  Or at least the ones used in BC-604 and BC-684 are.  My guess is that 200 KC was judged to be tight enough, and probably less chance of an error.

 

Robert Downs

 

From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On Behalf Of B. Smith
Sent: Saturday, February 23, 2019 12:05
To: Military Radio Collectors Association
Subject: Re: [MRCA] BC-654 Crystal Question

 

Thanks for the info Robert.   If in doubt RTFM. As usual I am guilty of not reading the manual. :-[
Looking at the crystal socket I have to ask the question as to why the designers used the 5 pin socket when they could have used a standard 8 pin octal socket. I assume the original design used a special crystal holder the "DC-12"   that fitted the 5 pin socket. Photo of the socket is below.   I will have to work on my "five minute" adapter perhaps I can find a 807 that has gone South and salvage the 5 pin base. Then the question of using 200 kcs as a calibration point for so many different radios, BC-1306, GRC-9, ART-13 etc.  Was this 200 kcs frequency chosen to make it easier for the operator to calibrate  as he would not get confused with so many calibration points and perhaps use the wrong one on his dial?   Or was 200 kcs utilized to save quartz due to the smaller size of the actual quartz on the 200 kcs rock vs. the 100 kc?
Z



On 2/22/2019 1:03 PM, Robert Downs via MRCA wrote:

Yes.  See attached photo.  And if you follow the list of superseded Stock Numbers far enough, they both end up with the same number, 2X97-200.

 

I don’t know why the photo ended up attached instead of embedded.

 

And it is the same crystal as ultimately used several other places, such as T-47/ART-13, BC-652, etc.

 

Robert Downs



 

From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On Behalf Of B. Smith
Sent: Friday, February 22, 2019 10:35
To: Military Radio Collectors Association
Subject: [MRCA] BC-654 Crystal Question

 

Did the BC-654 use the same 200 kcs crystal that was used in a BC-1306? An adapter utilized? Ebay photo below.
Z










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