PAA04552
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>
>At 07:43 AM 2/15/2000 -0700, measures wrote:
>>? However, when the 20m tap on a SB-220 is used for 30m operation, the
>>operating Q and the circulating current in the tank increases by c. 40%.
>> This causes a doubling of the I-squared x R heating in the bandswitch
>>contacts. Using the CW tap would help a bit, however, I would not take
>>the risk. 220 bandswitches are no longer manufactured.
>
>On the other hand, if he holds it to the legal 200W power for 30m, the
>I-squared part will be pretty small, and the risk probably commensurate.
>
Decreasing drive and anode current to reduce P-out does not reduce the
voltage swing across C-Tune -- if the amplifier is normally tuned for a
peak in output. Thus, the AC voltage across C-tune is not decreased by
reducing P. (The AC potential across C-tune is the major determiner of
tank circulating current -- and this is controlled by the anode supply
potential.) .
later, Pete
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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