>
>>
>>I would say that the 160 meter padding caps on the tune and load are
>>changing values due to heating....Most likely the load padders.
>>
>? the most likely answer. It could also be the Tune-C padders because
>the current burden is virtually equal. To minimize tank drift, do not
>tune up locked key. Also, the 800a7 has to be derated from 800mA to
>600mA for locked key. Another prob. is that HV sags unrealistically
>during locked key. For virtually all ssb amps, locked key is not where
>one should be.
>
>>My home brew "titan" has exactly the same symptom. (Same tank, same caps,
>>same tubes). The tubes are new, and the filament voltage is right on spec.
>>
>? With barium migration there is a slow drop in anode current as the
>grid temp rises. . With a drifting tank, anode current is virtually
>constant. The great mystery is why the Titan's designers failed to read
>the specs from the cap. manufacturer.
>
>cheers, Jim.
>
>I don't think the designers of the Titan read any specs on any of the tank
>components. The first time I saw a Titan with the lid off was two years
>ago in Dayton when the prototype of the "Titan II" was unveiled. I was
>shocked!
I was shocked when they said they did not want VHF suppressors to get hot
at 28Mhz.
>(no pun intended) I have seen more robust tank components in Heath
> amps rated at 1/4th the power.
>
>This seems to be the norm in amp design these days...caveat emptor!
>
There are apparently few people who understand the significance of RF
current. Consider the number of ham radio amps that do not cool the tank
circuit. In commercial amps, it is common to put cooling water through
the hollow copper tubing used in the main L.
cheers, Phil
>
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampsfaq.html
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>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
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Search: http://www.contesting.com/km9p/search.htm
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