k4sb@avana.net wrote:
>
> Jim, when I built my first ssb amp ( in 1956 for heaven's sake ) ( 4 6AG7s in
> GG and I ran
> 300 watts input with that sucker ) the article called for the use of the next
> higher band
> coil...ie ...op on 20, use a 15 coil and add capacity to ensure it will pull
> the coil down
> to resonance...I strongly suspect your amp might do 18Mhz in the 15 position,
> and 24 on 10
> is almost a certainty. All you do when using this method is increase the Q of
> the tank circuit
> which results in the necessity of retuning more often. Other than that, I
> modified a SB220
> by just putting in padding caps.
>
> Ed
Ed: It would be better from a logical standpoint, to go the other way.
If you use extra capacitance, the 'Q' raises to a point where
circulating become excessive and the result is heating of the tank coil.
The alternative is to lower the 'Q' with less capacitance and more coil.
(ie: Use the 20 meter position for 17 meter operation)
The downside is a lower level of spurious attenuation. However, most
of us use some external attenuation anyway, such as Low Pass Filters,
and that should take care of that problem.
See ya' de KL7HF
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