[AMRadio] BC-610 Xtal Holder

Donald Chester k4kyv at hotmail.com
Sun Mar 6 19:49:53 EST 2005

FT-243 xtals should work ok.  The BC-610 was designed just before WW2.  At 
that time xtals usually came in a round holder about the size of a 
half-dollar, with two pins that fit into a standard 5-pin tube socket (the 
pin spacing was not the same as that of the BC-610 xtals, though).  I think 
they made the  rectangular style xtal holder for easier storage as would be 
necessary with a military unit, but internally the construction was about 
the same; the xtal was sandwiched between two metal plates, relying on a 
spring to maintain a certain amount of pressure on the crystal plate.  In 
fact, I recall in years past I have removed the crystal plate itself from a 
BC-610 holder and put it into one of the older style round holders and it 
worked just fine.

The FT-243 didn't appear until during WW2.  I suspect they kept the  larger 
style holder because that was what was already in use in the field by the 
military, and they wouldn't have wanted to change styles of crystal in the 
middle of the war.

I am curious if anyone is using a pre-WW2 version of the HT-4.  What kind of 
crystal holder did it use?  Was it identical to the one in the wartime 

Actually, it shouldn't be too difficult to fabricate an adaptor.  The FT-243 
xtal will fit into an octal tube socket, for example into pins 1 &3, 2&4, 
3&6, etc (in other words you have to skip a pin).  Just find a brass rod the 
proper diameter, or maybe even a couple of pins from an old 6- or 7- pin 
tube base might be the right size to fit into the BC-610 xtal socket.  
Solder a wire to each prong, insert them into the xtal socket, and solder 
the leads to the octal tube socket.  You could just leave it dangling and 
get the beast to work, but with a few junkbox parts and some basic shop 
tools, it should be easy enough to turn out a permanent professional looking 

I have seen commercially made adaptors occasionally at hamfests.

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