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Dangit!

T

Tom Wells

My audio is getting a bit "clumpy", and occaisionally drops to 80%. Sounds like an underbiased amp. Pulling the first audio tube and reseating
it puts everything back to normal. I had the whole transmitter apart a week or two ago and must have disturbed something.
Different tubes act the same.. It runs fine for hours then fades a bit. I notice because the reverb on input 2 is then "too much"
and out of proportion. I'm suspecting it is a cathode bypass cap, since the bass is where the clumping is first noticeable.

I'm on my own for this one, as it is my own design. Can I even find my schematic, or will I have to read the circuit by visual inspection?
Did I even put part values on the schematic?

As if I didn't have enough to do.

Dangit!
 
During maint and re-install a week or so ago,

Clumpy-- was created by poor RF grounding at modulator.


4 db instability--
hardware-
cheap "bypass" switch in upstream "affordable" audio processor needed "exercise".
Reseating tubes in audio stages downstream made enough disturbance to vary the poor connection in the output path of the processor,
but nothing seems to be wrong on the modulator.

Time will tell.
 
No further occurances of low audio, and with improved the RF ground, the frequency stability of the oscillator is better than ever before.
It's very loosely coupled to the modulator in order to minimize "pulling" from the audio, but still drifted a bit.

With no oven, I've been accustomed to a 10hz tweak daily. It's just staying put now. Hope that continues.....
 
So flipping all on/off buttons on & off a few times did the trick? Could it hurt to blast them out with lead cleaner?
 
I'm suspicious of almost any spray besides Deoxit D-5. You never know if it's gonna melt or craze plastic parts.

In my case it was the "bypass" button on a compressor stage.
 
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