Overloaded Front end (Uniden PC 122 )

[Red Ranger]

My CB radio is not receiving like it should, acording to a former tech the front end is overloaded and suspects the Diodes need replacing in the RF gain circuit.

So can somone give me some advice where these diodes are located, and if it's not the diodes, it should be another Solid State component.

I suspect this radio was overloaded by high powered stations at truckstops(I got it at a pawn shop)

Can Somone give me guidance to help restore the recieve on this radio?

 

[dudmuck]

The documentation on that radio is poor, but it appears the same as the TRC-453, for which you can download the service manual.

It shows that D10 and D11 are the front-end AGC for receiver.
These are varactor diodes MC-301, and rf parts shows to use 1SS53.

Try lifting the one leg on each diode to see if receive comes back, but also D43 is part of that. Its possible that if you still dont have receive, then TR13 has been also blown.

 

[Red Ranger]

Opps! it's a Uniden PC 122 XL model!

I have looked on CB tricks and "highlighted" the paths from the RF gain POT, I got to check like half a dozen diodes with my multimeter. I am thinking it is probably the diode closest to the antenna input(D10, D11) I will check these! I should be able to check them with a mutimeter with diode tester.

 

[Red Ranger]

Checked D10, D11 and D43 and all check GOOD.

Could my radio be out of alignment?

 

[Wire Weasel]

All above is possible RR. Diodes, and better spec'd diodes for that application are cheap. Replace them all.

Have reputable tech look at it.

But I would spend too much fixing that old, basic radio. You can get a great loud new CB with extra features for under $200. Many examples discussed on this forum in other threads.