Guess what? I'm back with another noggin scratcher...

[350GA]

Merry belated Christmas to everyone!

I've got yet another radio that has me stumped, this time, I don't believe it going to be so easy...

So, I've got a new Cobra 29 LTD Classic on the bench, just finished my IRF520 conversion and tune on it, which I have done hundreds of before,(no clipped limiter or jacked up audio mods lol).

It's making fantastic peak and average power (9w Bird average/48w PEP), nice and clean on the spectrum analyzer, with the top cover OFF...

But as soon as I put the top cover all the way ON, the power drops to around HALF of what it was doing with it taken off! I have never seen this before, ever.

Any ideas from the braniacs here? Thank you!

 

[nomadradio]

Ground screws on the corners of the circuit board loose?

Blown disc caps connected to the solder pads of those ground screws? A typical sign that a radio was connected to the antenna during a nearby lightning strike. Sometimes the only visible damage is a tiny nick in the rim of the disc, usually in the space between the lead wires.

This is a sorry trick we saw with the old President/Uniden HR2510 radios, but not with this one.

73

 

[Handy Andy]

Take your DVM, test the Speaker wires, then test one them to the Speaker CASE.

If case to speaker - if it shows ~8 to ~16 ohms, your Speaker is causing you this grief.

Else the Speaker ground is too weak - you need to repair the Microphone and or the Speaker Jacks both EXT and PA - then verify the caps are not shorting your effort to ground.

Think of this as a Talkback mod repair...