Fw: NC-190

[joe sloss]

I have a NC-190 that seems to have more than usual hum which is not affected by settings of the AF gain pot.  It does not originate with the filter caps.  Grounding the grid of the audio output tube with a 0.01 mfd cap has no effect leading me to conclude the problem lies with this tube and associated circuitry.  National's  design, such as mounting  lengthy audio leads near the transformer and AC lines leads one to suspect a design flaw.  Anyone had experience with this problem w/ a NC-190.

Thanks,  Joe k7mks

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