>That is exactly my point, Rich. With one tube I get proper tuning at about
>1/3 mesh of the plate tune cap. (Which, by the way, grid dipped nicely
>around 50MHz) I expected about 2/3 mesh with two tubes. That's why I went
>to 1.5 T on the L from 3. Yet, with two tubes min tune C results in max
>power output. It is illogical. . .
>-ap
You did not state what the calculated value of L should be. You did not
state the measured value of L with two tubes. Stating the number of
turns does not get it. It is the inductance that counts.
>
>measures wrote:
>
>> >
>> >Amp aficionados, et al;
>> >
>> >I have a 6 M SB-220 conversion that works quite well with
>> >one tube. Input SWR is 1.1:1 and output plate tune is at
>> >about 1/3 mesh. Efficiency is as expected. However, when I
>> >put two tubes in the beast I have to go to min plate C for
>> >max output.
>>
>> Two tubes requires that L be cut in half and C-tune be doubled to
>> maintain the same Q. Guessing at tank values is not good engineering
>> practice. And remember, Pi-networks are not quite resonant on their
>> operating frequency.
>>
>> cheers, Art.
>>
>> - Rich..., 805.386.3734, www.vcnet.com/measures.
>> end
>>
>> --
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>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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