[Amps] SB-200 80 Meter dilemma

[R.Measures]

**  Sounds like the 80m Tune-C padder cap switch contacts have been 
evaporated by occasionally arcing when they are open (40m - 10m).  The 
arcing is apparently caused by an intermittent VHF parasite.  To find the 
frequency of the parasitic oscillation, unplug the amp and measure the 
resonance present at either side of the DC-blocker cap.  

>I own the SB-200 amp. It operates fine on 40-10 meters. I have two well worn 
>tubes. But the amp does not want to function properly on 80 meters. On 80 
>meters the amp indicates proper plate current but very low grid current. 
>On 80 
>meters the amp puts out a minimal 150-200 watts as indicated on my watt 
>meter and 
>then drifts down while exciter power is applied. Any thoughts on diagnosing 
>the problem or leads I might pursue? 
>
>Help,
>Don
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