Cobra 148 gtl 1992

[kaos513]

I

Tell me; just how does a transistor responsible for SSB ALC control have ANYTHING to do with repairing/checking the power input and your 'transformer?'!?
Absurd.

i just touched it after reading one of the forums with same issue.

 

[Robb]

I
i just touched it after reading one of the forums with same issue.

Really? What happened with your 'sporadic voltages'?

 

[sonoma]

 

[kaos513]

actually the radio died again so i gave up and its up for parts

 

[kaos513]

actually the radio died again so i gave up and its up for parts

I didn't give up on it I managed to get it back up and running but my only problem is now I have no channel display but everything else works on it.any help would be appreciated thanks.

 

[mechanic]

I have two older 148s and have replaced the electrolytic capacitors, that alone brought them back to life. Older caps have a tendency to lose the ability to keep their 'form' and can lose it quickly if stored for a while. Sometimes they can short causing damage if they open then there is a loss of voltage supply or filtering. Older radios and transceivers are most likely to suffer from this. A good ESR meter or using a scope should be able to find this but a general rule is to just replace the capacitors. Caps that are out of spec can damage those components that rely on them for DC isolation and voltage supply (smoothing). This is especially so in the B+ buss or supply.
When replacing the AM power regulator or voltage regulator, the associated electrolytic capacitor(s) should also be replaced. If the working voltage is 6 or 10 volts you can use 1.5 times that value with confidence, make sure the μFarad rating is the same. Double check the polarity! Any use of tantalum caps in the PA should be replaced at the same time.
All of the above is true with all older gear even receivers.

73 mechanic