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Sprucing up a Lafayette

B

baystatejack

Member
Dec 2, 2009
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Hello to all!
I just bought a Lafayette Comstat 25A tube radio. I had one like it as a kid and loved it. This old rig needs some TLC. I'm gonna start by de-oxing the controls and cleaning all the connections. I am able to transmit only on a few channels, so I'm guessing some of the crystals need to be replaced. Where can I find new crystals that will work with the Comstat and would it be worth it? One of the channels I can't use is ch. 19. (27.185 MHz). It has been a long time since I heard a relay click while keying the microphone. For that reason alone, I'm willing to sink a few bucks into this vintage gem.
Thanks for any advice!
 

Clean all the connections channel selecter, squeich, volume, crystal sockets etc, first and see if it transmits on all channels if you need crystals or tubes KENS ELECTRONICS should be able to help you, have fun neet radio !
 
Thanks Scout 943. I am slowly cleaning the guts. While going through the radio, I found an old piece of paper with a crystal taped to it. The crystal is 41.10 and the place on the channel selecter it was origionally soldered to had the wires soldered together. All the tubes seem to be working, it's just really dirty everywhere. Is there a cleaner other than deoxit that I should be using?
 
comstat25.jpg
 
baystatejack said:
Thanks Scout 943. I am slowly cleaning the guts. While going through the radio, I found an old piece of paper with a crystal taped to it. The crystal is 41.10 and the place on the channel selecter it was origionally soldered to had the wires soldered together. All the tubes seem to be working, it's just really dirty everywhere. Is there a cleaner other than deoxit that I should be using?
Click to expand...

Those wires would go to an external VFO. Nice to find the original crystal.

PR
 
I will take a few pics of this Comstat's innards if anyone is interrested. My first Comstat was a mobile in my 1968 Dodge Charger. It fit perfectly right in the front of the center console. If I remember correctly, I used a Turner amplified (blue & white) mic with it. Many evenings my buddies and I would drive up to the highest areas centeral New England had to offer and work skip big time. I loved that old radio and to this day regret ever selling it. I guess that's why I'd like to give this old girl a new life.
 
Peddler said:
comstat25.jpg
Click to expand...


That pic is a Comstat 25 which is pretty rare. It had channel 22A AND channel 22B as well as enough crystals to get all the A channels. That was a big deal back then and could get you noticed by Uncle Charlie pretty quickly.

The Comstat 25A is a regular 23 channel job and can be modded for channel 22A
 
I'll unsolder the wires and see what I get. Oh, I messed up on the model # of the radio iit IS a Comstat 25. It has chan A & B in red letters.
 
baystatejack said:
Hello to all!
I just bought a Lafayette Comstat 25A tube radio. I had one like it as a kid and loved it. This old rig needs some TLC. I'm gonna start by de-oxing the controls and cleaning all the connections. I am able to transmit only on a few channels, so I'm guessing some of the crystals need to be replaced. Where can I find new crystals that will work with the Comstat and would it be worth it? One of the channels I can't use is ch. 19. (27.185 MHz). It has been a long time since I heard a relay click while keying the microphone. For that reason alone, I'm willing to sink a few bucks into this vintage gem.
Thanks for any advice![/QUOTE

I have the Comstat 25A with some of the very same problems. Mine also has a receive issue. I'll find a good tech to go thru it the first of the year and get it up and going. Good luck getting yours fix.
Click to expand...
 
Make a list of all the channels that don't work or are way off frequency.

You can check using another radio nearby in ssb mode. Zero beat the carrier to check frequency.
 
HiDef: Make a list of all the channels that don't work or are way off frequency.
You can check using another radio nearby in ssb mode. Zero beat the carrier to check frequency.

________________________________________________________________
HiDef, Sorry it has taken so long to get back to you. I have cleaned everything on the Lafayette. I do have crystals i chan A & B. The channels that DON'T work are: 17, 18, 19, 20. Everything else seems to xmit and recv okay. The pots are clean and quiet. The unsoldered, loose crystal is 41.10.
The other identification on the crystal is: NDK Japan. Does that mean frequency 41.10 handles channels 17 thru 20?
 
http://www.cbtricks.com/radios/lafayette/comstat_25/graphics/lafayette_comstat_25_sch.pdf

Yes, it looks like the 41.10 rock is the reason 4 channels are out.

Here's how the synthesizer works:

There are two master oscillators one for transmit and one for receive. One uses a 6.255 crapstal and the other a 6.200.

The channel selector selects from 2 banks of crapstals. One bank is the 41.XX bank and the other is the 7.7XX bank.

Take out a calculator and pick any pair from the two banks. Say 41.10 and 7.705. Subtract the 7.7XX number from the 41.XX number.

Now subtract another 6.2 mhz for the transmit master oscillator. You will now land on a CB channel number.

The 6.655 master oscillator offsets the frequency by 455 khz which is the receive I.F. frequency.

I just tried this with my calculator and learned my calculator is defective!

First time I've seen a calculator actually give wrong answers!!!

Off to the trash.

The 6.2 rock will have a trimmer capacitor near it to fine adjust transmit frequency. Don't touch it until you have a good counter or a radio with ssb to check it.
 

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