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Question About Using a PAL VCO With A 23 Channel CB Radio

Raccoon

Active Member
Oct 27, 2005
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I have a PAL VCO ... it's the D5 model , and I'm not finding a lot of information about them online, or much of anything about hooking them up in a radio . So I figured I'd ask a question here and see what I can find out . I have three 23 channel base stations , and I'd like to try this out with at least one of them , but I'm not sure if I can , and if I can ... which crystal is supposed to be removed in order to use it ?

The base stations are :

1. Kris 23 +

2. Lafayette Comstat 23 (the original model)

3. Pearce Simpson Bengal

any help/information would be greatly appreciated ... and thank you in advance .
 

nomadradio

Analog Retentive
Apr 3, 2005
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It's rare to find a PAL that hasn't been hacked, and its frequency coverage changed. Odds favor a mismatch between what's inside a used PAL and the radio the buyer wanted to use it with.

23-channel radios used literally dozens of crystal-frequency combinations. A slider has to be adapted to the particular crystal that you'll pluck out of the radio, to hook the slider cable. This is why you'll see the info for CB sliders broken down into a handful or dozen or more "versions", each delivering a different frequency to put you on channel 1.

Inside you PAL, at the very lower-front corner of the circuit board is a crystal in a socket.

Conventional VFOs like a Siltronix or Maco or Tram wire the oscillator circuit to put out the frequency your radio uses. This results in multiple "versions", each with different parts in the oscillator circuit.

The PAL is different. Every version uses an oscillator circuit that runs from 5 to 5.5 MHz. Just to start, this makes it more stable than the other types. The crystal is chosen to mix with that 5 MHz signal and produce the frequency needed for a particular radio.

Downstream from the mixer circuit that combines the two frequencies you need the exact setup for the radio frequency that you want, but this is true of all external VFOs.

Have a look at the frequency marked on that crystal. This will tell you more about what that particular PAL is set up to do than the sticker on the rear panel.

Just to make it more interesting, PAL changed their letter/number 'type' designation scheme after producing them for a few years. Makes looking it up more of a challenge. If you have a frequency counter, hook a patch cord from the PAL's output jack to the counter input and see what's coming out.

And if it's been "hacked" off the air, this could be your first hint.

For the moment, let's just assume that the "D-5" setup has not been molested. This version puts 37.75 MHz into the radio for channels (I think) 13 to 16. The original PAL dial started at channel 13 and went up from there. Nobody contemplated "lower" channels 45-plus years ago.

Whups, don't have the Kris 23-plus info here at home. Might have the 37 MHz crystals, don't know.

Likewise the Comstat 23 isn't on CB Tricks. The "25" model is NOT compatible, just don't remember if they both used the same crystals.

The Pearce-Simpson Bengal's crystals are NOT a match at all. You'll find that the D-5 PAL works mostly with AM-only CBs.

The first two radios are bound to be on file at work. I'll have a look next time I'm there.

73
 

Dmans

Sr. Member
Jan 22, 2017
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Georgia
The attached may help.

73
David
 

Attachments

  • AM 14950-23290-11275-11730.pdf
    19 KB · Views: 8
  • AM 16965-9545-1000.pdf
    20.8 KB · Views: 5
  • SSB 11805-73615-73585.pdf
    19 KB · Views: 4
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