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Cobra 28a recapped, low modulation.

Uncle Ronnie 336

Well-Known Member
Apr 28, 2020
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Getting about 9w peak from this after a recap. This radio is going in a 70s era Ford van that's currently getting restored. It has a home. The limiter is an ancient design and I don't exactly want to snip it. Did get more audio by changing r131 to 1.8k but any more and audio warbled. My guess is there's something held back in the af amp or the driver doesn't peak hot
 

Also, in order to properly kick an amp, r134 is going to be the resistor I pull for the tap points for a tip120 NPC mod.
 

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you're just not going to get much more than that from that final.

it's only rated for 10 watts and 2 amps.

looks to me like pretty much full VCC is present at the collector of the final.
you might make sure your relay contacts are all very clean, and that the CB/PA switch is clean in order to get all the voltage to the final that you can, but i think it just is what it is. (what voltage do you read at TP8?)

R134 does look like the resistor to pull for the swing mod.

this radio looks like it would be a great driver for a 1x4 pill amp.
set that deadkey at 1 watt and let it swing up to 8 or so.
LC
 
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