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Louie, Technician
Category: Consumer Electronics
Satisfied Customers: 12305
Experience:  25+ yrs. experience in the field and 5+ yrs. online, down to component level.
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I just installed a cb in my truck and receive no

Customer Question

I just installed a cb in my truck and receive no transmissions and a lot of engine interference. The SWR was good at 1.25.
JA: What's the make/model of your device? How old is it?
Customer: Brand new...Uniden 520
JA: How long has this been going on? What troubleshooting have you tried?
Customer: Just installed it today
JA: Anything else you want the electronics expert to know before I connect you?
Customer: I'm not sure what that would be. Just need help figuring out the issue with this.
Submitted: 8 months ago.
Category: Consumer Electronics
Expert:  Louie replied 8 months ago.

Hi and welcome to the site, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.

Initially, bear with us; re-confirm and post back with the complete model number Uniden. Would this be a PRO520XL ?

Still, have you tried with:

  • ANL off;
  • SQ full counterclockwise; and
  • RF GAIN max clockwise?
Customer: replied 8 months ago.
to all.
Expert:  Louie replied 8 months ago.

I understand.

Disconnect the PL-259 connector. In its place and for test purposes, carefully insert a length of wire to serve as test antenna (preferably 9' long). Determine if the S/RF would show incoming signals. DO NOT TX / press PTT.

The above would determine if it is internal to the Uniden or an antenna issue.

Customer: replied 8 months ago.
I am traveling and unable to do this step. Any other suggestions?
Expert:  Louie replied 8 months ago.

Loosen fully the outer/threaded part of the PL-259. Slightly pull back so that (only) the center/male part of the PL-259 is in contact with the middle portion of the antenna connector.

Might not be as effective as just a length of wire but, it should receive near / strong signals.

Customer: replied 8 months ago.
Thank you. So, unscrew the connector, leave the male part inserted, and its OK to transmit and leave it that way if it corrects the problem? Also, should the plastic washer be left between the antenna and the base. It's a K30 magnetic mount.
Expert:  Louie replied 8 months ago.

Negative, no TX. This is a test for the receive part only as above "...receive no transmissions..."

And how many volts is the truck please?

Is the CD directly wired to a 12V battery?

Consider making another ground connection to the metal body of the truck from the rear/body of the CB radio.

Also, please provide a clear picture of the "... plastic washer...between the antenna and the base..." Click HERE.

Customer: replied 8 months ago.
Ok it will be about 30 min and I'll try that and get back to you for the next step. What about the washer question? I noticed it does make a difference in the SWR reading. 1.5:1 with it, and 1.25 without it.
Expert:  Louie replied 8 months ago.

Normally should not cause a change in the SWR as it is meant more for mechanical function rather an electrical. It ensures that the antenna is lock tight to the magnetic base with no free play just like a lock washer.

...hence my request for pictures.

Customer: replied 8 months ago.
It's standard 12 volt system. Can't wire direct to battery without goi g through the firewall. Have it plugged into the cigarette lighter receptacle. Please see attached.
Customer: replied 8 months ago.
Wired in this manner for today's trip. Have installed many cb's in the past and never ran into this issue.
Expert:  Louie replied 8 months ago.

The "...plugged into the cigarette lighter..." would account for the "...lot of engine interference..."

Consider the earlier suggestion of hardwiring a ground strap from the rear of the Uniden (preferably a screw near the antenna connector) to a close metal part, bracket / part of the truck's body. This would serve to improve the ground plane (virtual RF ground).

Is the bottom /whip holder threaded all the way down?

Customer: replied 8 months ago.
The whip holder is threaded all the way to the base. Will try the ground suggestion now.
Expert:  Louie replied 8 months ago.

Yes please.

Customer: replied 8 months ago.
Ok...added the ground and have the connection unscrewed but still plugged into the back of the radio. Getting some engine noise but not as much. No reception of other transmissions.
Customer: replied 8 months ago.
Still have SWR/power meter connected inline. Should I remove that?
Expert:  Louie replied 8 months ago.

Apologies; Internet was sluggish if at all.

Yes please for test purposes; K30 -> magnetic mount -> coaxial cable -> PL259 (male only) -> CB's antenna connector (center hole only).

The radio should be receiving:

  • if yes, then it would be an antenna problem;
  • if not; then it would be a radio problem.
  • if the added grounding = reduced engine noise, then it would be to your best advantage to connect directly (if able) to the battery terminals (but retain the grounding to truck"s body).

Others to consider are noise filter similar to the product shown HERE (not as an alternate to the direct battery connection but) for further help.

Customer: replied 8 months ago.
When I did not hear back from you I explored other options on my own. I found a solution, so your suggestions, although they covered the more obvious issues, did not create a solution. Thanks anyway.
Expert:  Louie replied 8 months ago.

I understand.

Still, great! Good to hear that the issue has been resolved, congratulations.

Customer: replied 8 months ago.
Considering that fact will I still be charged?
Expert:  Louie replied 8 months ago.

Sorry but my participation is strictly limited to technical, repair and/or installation issues.

Request for cancellation, refunds as well as billings & payments concerns are best addressed by Customer Support. Please click HERE or go to

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