Hi all,

I am trying to bench test my factory cb radio and cannot get the cb to pick up any channels. Has anyone had to trouble shoot this type of problem? I am using the correct factory antenna, splitter, wires, mic, and both my Motorola boxes result in the same outcome: it just scans through all the channels and never picks anything up. One of my boxes is NOS so that isn't the issue. When I stop on channels I can't get anything. Is this a grounding issue? I have two of every part, no success with any combination. I ground the box to the battery on my bench as well.

Thanks

 

Getting any static? Or no sound at all?
Squelch and/or RF Gain could be wound up. Dead speaker? Is there an ext jack you can try?
Is there a PA switch you could have left on?
You haven't transmitted without the antenna connected, and blown it to smithereens?

 

I am not getting any static, but I can hear the mic key through the speaker. Not an expert on the squelch and gain, but I tried it in all positions. Could having it setup in my basement make a difference? Its the factory setup so I am not sure how powerful it is.

 

 

Basement likely killing signal. Never personally had one, but I wouldn't think it would be powerful like that to pick much up with an antenna hidden underground in your basement.

 

Thanks for all the suggestions all, I will give it a shot.

 

cb (citizens band) is a line of sight radio. NEED I SAY MORE??

 

More applicable to UHF.
AM has the advantage of skip, but with a drop in clarity.

 

Try it with a CB mobile or base antenna. Note: A short antenna with a splitter is a compromised antenna, especially on the 27 mhz band, considering 1/4 wave length is 102" That's why the obtrusive 102' whips work well. Also, a properly matched antenna (< 1.5 : 1 swr) is important for maximum transmit & receive range.
Some truck stops have a CB shop, they could test your unit. If you need a mobile antenna to test with, let me know and I can ship one to you.

 

Thanks for the info, this is great to know!

 

If I understand correctly, you're using a mobile CB radio and mobile CB radio antenna. If that's the case then you can't test it properly - or safely - in your basement.

First do as others have said, check and re-check the squelch. You also want to be sure (if so equipped) to turn the RF Gain for *maximum* reception, otherwise your radio will just endlessly scan.

If you're not "hearing" anything at all from the speaker, after checking your RF Gain setting, you then might try connecting a "external speaker" into the speaker jack (if so equipped) just to be sure your built-in speaker isn't bad.

The suggestion above is good - to make sure the PA ("Public Address") switch isn't on. When that's on, the radio portion of the CB doesn't work because the radio goes into a loudspeaker/bullhorn mode (you'd need a optional PA accessory loudspeaker to use that function)




***** Putting this purely in layman's terms for easy understanding *****


A mobile antenna is specifically designed to be mounted on a vehicle to work correctly.

Technically (radio-wave wise) a "mobile" antenna is specifically designed as only "half" of a antenna. It needs to be mounted to a metal vehicle to work right (the metal vehicle shell makes up the "other half" of the antenna)

The engineers who design mobile antennas purposely make them this way, it's only "half of antenna" (electrically speaking) until it's mounted on a vehicle. Your metal vehicle makes up the other "half" of the antenna

The mobile antenna itself, combined with your metal vehicle - then equals a actual "complete" antenna. When you use a mobile antenna indoors, you're (harmfully) trying to use your radio with a incomplete "half" antenna.

Trying to use a mobile antenna indoors will only harm the CB radio. Any time you key the mic without a antenna, or without the antenna mounted correctly, it can (and eventually will - very soon) fry a certain transistor inside the CB. CB repairmen see this all the time and is one of the first things they look for.

In a nutshell, most (not all but most) CB radios quit working for a few simple reasons:

• A bad microphone cord/cable or the actual mic itself - preventing the mic from keying properly to speak. A bad mic or mic cable also prevens the radio from "receiving" radio signals too (many radios lose receiving capability if something in the mic stops working)
• A bad antenna coax cable or bad antenna stud-mount or bad antenna itself (all commonly go bad and are likely culprits)
• Or something in the radio itself goes bad, often a small transistor called the "final transistor" - this commonly happens when someone unknowingly keeps using a radio when their antenna or antenna stud or antenna coax cable goes bad or is broken by a treelimb etc

You have to picture the CB radio as a hot running V8 engine. What would happen to that hot revving engine if you completely plugged the exhaust pipe? It would be waaaay too much backpressure and could damage the engine right?

Well it's the same principle with a CB. When you press the mic key (like revving a engine), the radio signal (the radio's "hot exhaust") MUST exit the CB radio through the antenna coax & antenna (which is the CB's "exhaust pipe").

If the antenna coax cable, or antenna stud, or antenna itself is bad - the CB radio signal "exhaust" (it's radio signal) cannot properly leave the CB like a plugged exhaust system. Most or all of the radio signal instead backfeeds back into the CB and usually burns up the CB transistor in a very short time.

It doesn't take long to do this, sometimes even as little as 15-30 seconds of transmit time.

The SAME thing can/will happen if you're trying to use a "outdoor" mobile antenna while indoors. The antenna won't let the radio "exhaust" out properly and can or will harm the radio. A "mobile" antenna is not a "complete" antenna and will backfeed radio signals back into the CB.

CB radio signals are ONE-WAY only. Once you're transmitting, they MUST transmit out of the antenna into the airwaves. If there is any problem with your coax or antenna stud or antenna, the radio signal backfeeds back into the radio and often blows that transistor.

To prevent harm to a CB radio, a "mobile" antenna should always be mounted on a vehicle to work properly. Otherwise you'll be backfeeding your radio signals back into the radio, causing harm.

Honestly, it's quite common. For instance: a trucker will be yakking-away going down the road and not notice that he just clipped a low-hanging branch and broke his antenna. Since he's continuing to talk, he's unknowingly burning up his transistor in his radio. After a minute his radio dies and needs to be brought in to a repair shop. Another common no-no is to press the mic button when no antenna is connected at all (kids often do this!) and the instant backfeed ruins the transistor. Trying to use a outdoor mobile antenna inside is almost as bad as using a broken antenna or even no antenna at all.

Don't do any more basement "transmit" testing. You CAN listen/receive in the basement - but NO TRANSMITTING indoors on a "mobile" antenna.

As said by others, a good CB shop has the proper test station to test your radio. They will have a special indoor "test antenna" and simultaneously will be watching their test equipment meters to see what the radio is or isn't doing.

Not all "CB shops" are created equal and many are just interested in selling you a new or used CB.

If you have a vintage collector-CB (like a Ford factory CB or other special classic model or one that belonged to Dad or Grandpa etc) then you want to choose a reputable CB repair shop that has the know-how **and willingness** to fix older classic radio gear.

Most problems are with the mic or antenna coax or antenna stud or antenna itself, and lastly the radio. Not always but usually.

I'd start with the mic, it's the first thing to have a problem (usually just a disconnected wire in the handset or needs a new cord from age or being overstretched). More often than not it fixes a good deal of radio problems.

It could be a issue with the CB radio itself, but more commonly (if not first the mic) then it's the coax cable or antenna stud or antenna. Those items aren't meant to last and go bad very easily, especially if they are not an excellent name-brand.

Ok I'm tired cold and hungry and am going to retire for the night.

Don't get worried or lose hope on a good old radio, especially if it's a factory collector model or has sentimental value.

After a couple of decades of extreme back-breaking heavy/industrial labor, I later got into electronics have a background in radio communications both as a hobby and professionally. Wanted to write hoping to help a little. Maybe some of the things outlined might help some other readers too

 

Thanks great info!