Help vintage CB radios and crystals

[metalmoto]

Hello everyone,

Just as a short introduction. I got interested in electronics and electronics repair as a teenager. First building RS and Heathkits on my dining room table. This interest has followed me my entire life up until age 60, where I am now. In my mid 20's I became interested in antique radios in which my collection has grown too large for me to handle. Also vintage 70's stereo componets has taken a hold on me. But I am here to discuss and ask questions about my vintage CB radios that I collected in the 1980's.
At my age now, now comes a time where I must thin out the herd. As I am going through my collection of CB radios. I have some questions about CB's that use discreet crystals to select the standard channels. I have quite a few that only tune to 3 or 5 channels. And that's where my confusion comes in to play. For example, I have a handheld Realistic TRC-75. A 3 channel unit, I wanted to use as a test unit, to confirm if my vintage mobile were working OK. As I plan to sell them on eBay or perhaps here, as I noticed, you also have a classified section. To my question... As I understood, the TRC-75 requires 2 crystals of the correct and "same" frequency, to be inserted into both the transmit and receive sockets, for the unit to both broadcast and receive on the channel selected from the A-B-C selector switch on the unit. As this sounds logical to me. Opening the unit, I find the channel 14 crystal in the transmit socket, but a totally different crystal, with a different frequency inserted the receive socket of the same channel selector for receive socket.
"Please forgive my ignorance on the subject". But shouldent the both be of identical frequency?
This is just the beginning of the many questions I have about crystals.
(But I do know that "some" vintage units that use "discreet" crystals often use a few a few different crystals "combined" to make the entire 23 or 40 channel band, using a certain combination of different crystals). However, I just want to know my first assumption is correct for now?
Thank You.

 

[K9KLC]

Hello everyone,

Just as a short introduction. I got interested in electronics and electronics repair as a teenager. First building RS and Heathkits on my dining room table. This interest has followed me my entire life up until age 60, where I am now. In my mid 20's I became interested in antique radios in which my collection has grown too large for me to handle. Also vintage 70's stereo componets has taken a hold on me. But I am here to discuss and ask questions about my vintage CB radios that I collected in the 1980's.
At my age now, now comes a time where I must thin out the herd. As I am going through my collection of CB radios. I have some questions about CB's that use discreet crystals to select the standard channels. I have quite a few that only tune to 3 or 5 channels. And that's where my confusion comes in to play. For example, I have a handheld Realistic TRC-75. A 3 channel unit, I wanted to use as a test unit, to confirm if my vintage mobile were working OK. As I plan to sell them on eBay or perhaps here, as I noticed, you also have a classified section. To my question... As I understood, the TRC-75 requires 2 crystals of the correct and "same" frequency, to be inserted into both the transmit and receive sockets, for the unit to both broadcast and receive on the channel selected from the A-B-C selector switch on the unit. As this sounds logical to me. Opening the unit, I find the channel 14 crystal in the transmit socket, but a totally different crystal, with a different frequency inserted the receive socket of the same channel selector for receive socket.
"Please forgive my ignorance on the subject". But shouldent the both be of identical frequency?
This is just the beginning of the many questions I have about crystals.
(But I do know that "some" vintage units that use "discreet" crystals often use a few a few different crystals "combined" to make the entire 23 or 40 channel band, using a certain combination of different crystals). However, I just want to know my first assumption is correct for now?
Thank You.

The transmit and receive frequencies are not the same exact frequency no. We used to switch the CH 23 crystals in radios like the Sonar Model G, and Johnson Whiteface/blackface, and end up on 26.800 which at the time a wrecker company was using for their tow truck frequency. Think IF frequencies and mixing in the radio.

 

[WA0CBW]

No, they will be different by the IF frequency of the receiver. In a superhet type of receiver the local oscillator (receive crystal frequency) mixes with the incoming channel frequency and you get the sum and the difference between the two. The difference is the IF frequency of the receiver (commonly 455KHz in a single conversion or 10.7MHz in a dual conversion). In crystal synthesized radios a number of crystals are mixed together to get the required frequencies for receive and transmit. There is a little more but this gives you the basics..
BB

 

[metalmoto]

Thank you both for the replies. Helped me to as I was going through my bag of loose crystals. 5 are old Philadelpha Police/Fire/Turnpike scanner crystals. 5 different CB receive crystals, 1 transmit. One 49MHZ RC crystal, and 1 TV color burst crystal. It's been years, but now I remember I had 2 old scanners that used discreet crystals. One base and one mobile. Sold the scanners 25 years ago.
I haven't gone though all the CB radios yet. Most are either 23 or 40 channel, a few are old 3 or 5 channel units. Probably junk now, but who knows?

 

[chief21]

It's been a very long time, but as I recall, CB crystals did not usually list the actual crystal frequency, just the CB channel number and either T (for transmit) or R (for receive). Am I remembering correctly?

 

[K9KLC]

It's been a very long time, but as I recall, CB crystals did not usually list the actual crystal frequency, just the CB channel number and either T (for transmit) or R (for receive). Am I remembering correctly?

Some listed the ch, some listed the frequency and some actually listed both, depends on where they came from.

 

[metalmoto]

Your correct, some are marked T or R others are just marked with the frequency.
I had to Google each one, or figure them out, using + or - 455Khz and using the chart of CB transmit frequencies. The one 5 channel mini CB radio I have still has all the crystals inside. Unfortunately it appears that it needs repair. With the squelch turned completely down, it dosen't make a sound from the speaker. Maybe a dead output transistor. Finding a replacement is probably impossible today:-(

Yes, I just confirmed both output transistors are bad, shorted.
I doubt it's worth replacing them at this point.

 

[K9KLC]

Yes, I just confirmed both output transistors are bad, shorted.
I doubt it's worth replacing them at this point.

Did you take them out to test them or, were they still in the circuit?

 

[K9KLC]

With the squelch turned completely down, it dosen't make a sound from the speaker.

While a dead short on anything can effect the power supply voltages to any other circuit, I've seen hundreds of output transistors bad and the radio's still receive. What's commonly called "output transistors" are usually assumed to be for the transmit side, not the receive side. While yes there could be an audio output transistor, it's usually referred to as audio output and not just output. I know jargon/shamargon, but hard to tell what's actually going on with your unit.

While it's nice to restore vintage equipment, and I do it myself, you often have to weigh out is it worth my time and the parts I'd need to buy to get it going, I have some vintage ham stuff I keep going, but that's more for myself and just personal satisfaction, than actual usage reasons. Also they have some street value yet whereas I don't know how much value would be in a 70-80's walkie talkie these days with the prices of new ones so cheap any more. Whatever you decide, good luck, hope it works out.

 

[metalmoto]

Did you take them out to test them or, were they still in the circuit?

In circuit, using 2 different testers and diode setting on my fluke.

Two Toshiba 2SB337 TO3 transistors on the back of it test shorted. Yes, it probably has other issues also.
I was was just thinking about installing in in my 25 year old Jeep Wrangler soft-top.
(I wanted a hard-top for more security, but finding a nice orginal Jeep TJ, unmodified one today for a good price, is like a needle in a heystack).
The soft-top gives no security. As anyone can un-zipper the rear, or rear side plastic window, and climb inside. My idea was to mount this little CB in the Jeep. No space for anything larger.
Installing a newer $300 mini CB is just asking it to be stolen. Especcially in the city...

Yes, we all have cell phones today, to call for help. I was once lost, trying to find a friends house.
No GPS yet. No signal on my phone. Had to stop at a pizza place, and use the cash-register girls phone to call for directions.

Something I will never forget. I was 9 years old. My late father was drivng us to a small summer house my father owned in the Pocono mts. My entire family in his 69 Nova, on the NE extenion of the turnpike going 70. Speed limit at the time.
Tie-rod broke, causing loss of steering control. Car hit the dirt/rock enbankment, and rolled 3 times.
Nobody wore seatbelts, nor did airbags even exist! Finally someone finally pulled over to render help. A guy with a van used his CB to call for help. Ambulance was first, state trooper took a while... Thank you van man! My father always had a CB radio in his cars after that...

Later he owned a 65 Ford Falcon. He drove us to the Poconos every weekend in that car for 5 years. Both my mother and father using that car. My mother left my Father when I was 18. The Facon was garaged and sat for 38 years. Before he died, I got the car. I got it running, but not drivable yet. Then I find the magnet mount antenna still in the trunk, still can't fiqure out where he fed the antenna cable to the dash. Don't want to cut the cable. unless I must.

Repairing the little Pinto Jr to install in my Jeep, was just a thought anyway...
I was remembering the past, and the guy in the van. His CB got us help.
I digress...

 

[K9KLC]

In circuit, using 2 different testers and diode setting on my fluke.

Two Toshiba 2SB337 TO3 transistors on the back of it test shorted. Yes, it probably has other issues also.
I was was just thinking about installing in in my 25 year old Jeep Wrangler soft-top.
(I wanted a hard-top for more security, but finding a nice orginal Jeep TJ, unmodified one today for a good price, is like a needle in a heystack).
The soft-top gives no security. As anyone can un-zipper the rear, or rear side plastic window, and climb inside. My idea was to mount this little CB in the Jeep. No space for anything larger.
Installing a newer $300 mini CB is just asking it to be stolen. Especcially in the city...

Yes, we all have cell phones today, to call for help. I was once lost, trying to find a friends house.
No GPS yet. No signal on my phone. Had to stop at a pizza place, and use the cash-register girls phone to call for directions.

Something I will never forget. I was 9 years old. My late father was drivng us to a small summer house my father owned in the Pocono mts. My entire family in his 69 Nova, on the NE extenion of the turnpike going 70. Speed limit at the time.
Tie-rod broke, causing loss of steering control. Car hit the dirt/rock enbankment, and rolled 3 times.
Nobody wore seatbelts, nor did airbags even exist! Finally someone finally pulled over to render help. A guy with a van used his CB to call for help. Ambulance was first, state trooper took a while... Thank you van man! My father always had a CB radio in his cars after that...

Later he owned a 65 Ford Falcon. He drove us to the Poconos every weekend in that car for 5 years. Both my mother and father using that car. My mother left my Father when I was 18. The Facon was garaged and sat for 38 years. Before he died, I got the car. I got it running, but not drivable yet. Then I find the magnet mount antenna still in the trunk, still can't fiqure out where he fed the antenna cable to the dash. Don't want to cut the cable. unless I must.

Repairing the little Pinto Jr to install in my Jeep, was just a thought anyway...
I was remembering the past, and the guy in the van. His CB got us help.
I digress...

Yes we all have stories from "the good ole days", My how things have changed. Given the radio you were thinking of putting in vs what you quoted at 300 bucks you're comparing apples to potatoes. There are a lot of radio's out there, even some HT types which is what you mentioned that are well well under 300 bucks. I'll let other "CB radio experts" chime in on some of those, good luck on your quest. Times, conditions, prices, and equipment have changed.

 

[RFI-EMI-GUY]

For well under a third of the $300 you presumed to pay for a CB radio, WWW.PRESIDENT.US sells a couple of entry level 40 channel AM/FM CB radios that can be hidden in a glove box or center console. For antenna, an NMO-27 permanently mounted will give you best performance * .

* You will probably have to mount on the hood or spare tire post. Lots of discussions in other threads about Jeep mounted antennas. Always a compromise with jeeps.

You can be the "Great guy in the Jeep" with one of these:

 

[metalmoto]

I understand. And after playing around with my old junk, I found 3 that still work.
Still, I'm sure none of them compare to today's radios in form and function.
I'll most likely put them on eBay, maybe someone will want one to tinker with.
My Jeep is an 01' TJ Saraha with a soft top and totaly stock. No joke the ol' 4.0 straight 6 is bullet-proof.
230,000 miles on her, and she keeps on going...
I needed a 4WD vechicle to get to work in the winter. Almost got fired from the job in the beginning, because my van couldn't even get out of my driveway... Jeep is now over 25 years old.
The huge 100+ year old factory were I worked, burnt to the ground February 17, 2025.
I was working that night of the explosion and resulting massive fire. We all escaped the building safely.
Almost 70 fire departments, mostly volunteer, responded to the 4 alarm blaze.
"Thank You All Firefighters, EMT and who work in the Emergency departments everywhere"!
Unfortunately, I lost my job and new carreer after 11 years. Nobody wants to hire a 61 year old man.
Company is now rebuiding state of the art factory, by the time it's finished, I'll be retired.
And currently, I'm caregiver for my bedridden wife and disabled daughter. Perhaps things happen for a reason, we don't quite understand yet?

Thanks to everyone for you help and advice about CB radios. Still concidering installing one in my Jeep. I have a vintage Craig L131 about which I will post more about in another category.

 

[RFI-EMI-GUY]

SPS Technologies. Holy cow I better stock up on my rivets! The good thing about CB radios is that They are all interoperable so if you have a good working 40 channel CB you are good to go. There is still a collectors market for them, and at same time they are cheap at garage sames and FB marketplace. I had a RS Realistic TRC465 AM/SSB that I should have kept. It was nice radio from the mid 90's.

 

[RFI-EMI-GUY]

 

[Mophead]

60 year old cb'r from the 80's in the Philadelphia area? We must have bumped into each other on channel 7 or 34 back then.