[NJARC] AK 80 question

[Al Klase]

Bill,

Well, this is pretty disturbing.  Clearly there are errors in the 
documentation, and maybe the original wiring.  Can you say FUBAR?

I'd disconnect the oscillator cathode from the rest of the circuit, and 
ground it.  The slider on the volume control raises the cathodes of the 
!st Det and IF above ground, while their grids are at ground for DC.  
this should, indeed, effect RF/IF gain control:  more cathode voltage = 
less gain.  BTW, 35's are remote-cutoff tetrodes, so they're intended 
for this sort of operation.

The alternative would be to leave the oscillator cathode connected to 
the volume control, and clear any ground on that circuit node.

Good luck,
Al

On 9/9/2017 6:37 PM, William S Zukowski wrote:
> Just remember
> Reply = Poster
> Reply All = Everyone
>
> _________________________________________________________
>
>
> Just restored an AK 80.  After replacing all the caps, noisy 
> resistors, two bad tubes, most of the rubber wiring that had most of 
> the insulation gone, it actually works.
>
>
> My question is about the "volume control" (see schematic): It's in the 
> cathode circuit of the oscillator, so when it's adjusted, it sounds 
> almost like a regeneration control, oscillating, etc..  It also looks 
> like the schematic is wrong.  It shows the cathode grounded, which 
> would negate any effect of adjusting the control. It's not grounded in 
> this set.  The radio is basically untouched, except for two 
> electrolytic caps already replaced.
>
>
> Thanks, Bill
>
>
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-- 
Al Klase – N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/

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