[Boatanchors] crystal question

[WA5CAB at cs.com]

The common US crystal controlled WW-II vintage FM sets operated between 
20.0 and 38.9 MC and used either FT-241 or FT-243 holder crystals that were 
multiplied several time to get to either the operating frequencies (sets using 
FT-241) or receiver mixer injection frequency (FT-243 crystals).  There were 
two bands defined, Armor and Artillery.  Infantry didn't get an assigned 
band until the late 40's.  Except for the tunable BC-1000, they mostly used 
either HF or the Artillery band sets.  

Channel numbers were assigned, from which you can read the operating 
frequency.  Armor band covered 20.0 - 27.9 MC and the channel numbers ran from 0 
to 79.  Artillery band ran from 27.0 - 38.9 MC and the channel numbers ran 
from 270 to 389.  Channel numbers on the FT-241 and FT-243 match but the 
FT-241 crystals frequencies were in the low MF range whereas the FT-243 crystals 
were higher, roughly 6 to 9 MC.  As Al mentioned, the FT-243 crystal 
frequency was multiplied several times to get to a frequency offset from the 
operating freq. by the IF freq.

Some other sets had channel numbers assigned.  The Pogo Stick radio 
(SCR-511, BC-745) had channel numbers from 1 to about 69 but they were arbitrary 
assignments and the channel numbers are not on the crystals, only on the 
BC-746 tuning units.  The BC-733 Localizer receiver had channel numbers in the 
700 range and used FT-243 holders with the channel numbers on them.  Crystal 
freqs are in the same general range as for the FM sets.  There were one or 
two other groups but I don't recall the details offhand.

In a message dated 12/07/2012 00:33:47 AM Central Standard Time, 
bluegrassdakine at hotmail.com writes: 
> You also listed ch numbers. What do the channels mean?  Some of my FT-243 
> rocks have channel no. listed. 
> 
> 
> On Dec 6, 2012, at 21:58, "Al Klase" <ark at ar88.net> wrote:
> 
> >For the technoweenie historian:
> >
> >These were the jeep radios developed by the Signal Corps Laboratory in 
> conjunction with Galvin Corp. (Motorola).  They use the so-called 
> crystal-saver architecture.  The crystal frequency is multiplied by 4 to provide the 
> local oscillator for a receiver with a 4.3 MHz IF. In transmit, the DC 
> output of the receiver's FM discriminator is used to frequency lock the TX 
> oscillator to the crystal controlled RX frequency.
> >
> >E.g., (8000 x 4) + 4300 = 36,300 KHz.
> >
> >Al
> >
> >On 12/6/2012 10:30 PM, WA5CAB at cs.com wrote:
> >>Assuming that the crystals are FT-243 types:
> >>
> >>SCR-609/610 (BC-659)
> >>SCR-619 (BC-1335)
> >>AN/TRC-20 (RT-111/TRC-20)
> >>
> >>Operating frequencies would be 36.3 through 37.4 MC.
> >>
> >>In a message dated 12/06/2012 20:20:53 PM Central Standard Time,
> >>cosmophone at yahoo.com writes:
> >>>Among a lot of parts I bought recently there were five crystals which, 
> I
> >>>guess, are for a military piece of radio gear.  The frequencies in 
> KHz/Kc
> >>>are:
> >>>
> >>>8000   channel 363
> >>>8025   channel 364
> >>>
> >>>8100   channel 367
> >>>
> >>>8175   channel 370
> >>>
> >>>8275   channel 374
> >>>
> >>>Can anyone enlighten me as to what equipment uses these and if they 
> have
> >>>any value in today's world.
> >>>
> >>Robert Downs - Houston
> >>wa5cab dot com (Web Store)
> >>MVPA 9480
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> >-- 
> >Al Klase - N3FRQ
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480