The bandswitch contacts may have been toasted. The fixes are: replace
the burned contacts, or replace the switch wafer.
>Sir,
>Thank you for your advise. I will try your suggestion. For
>clarification, are you suggesting that the switch contacts need repaired
>and/or the DC-blocker cap may need replacing?
>Don
>
>-----Original Message-----
>From: R. Measures [mailto:r@somis.org]
>Sent: Friday, February 27, 2004 3:40 AM
>To: Ka7lpo@aol.com; AMPS
>Subject: Re: [Amps] SB-200 80 Meter dilemma
>
>** 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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>>
>
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