[Amps] Fixed Padder Capacitors --- POSTSCRIPT

[Ed Swynar]

Good Day All,

Just a "...final-final" in the matter of fixed mica / ceramic padder capacitors in the final tank circutry of my 2x813 linear amplifier...

After I had removed & replaced my original series / parallel network of fixed padders in the plate tuning of the tank circuit (with a combination of a 250-pfd. fixed vacuum capacitor & a fully-meshed 3.5 kv air variable placed in parallel), I went one step further & removed the large doorknob cap that I used to switch in parallel with the big 3-section air variable loading capacitor on 160.

The replacement in this instance was actually the air variable loading capacitors --- placed in parallel --- out of a pair of junked Heathkit SB-400 transmitters that I have here. I had mis-givings about the "robustness" of these rascals (the plates are not that far apart, if you've ever seen one), but Bill Orr in one of his HANDBOOKS stated that a receiving-type air variable capacitor is perfectly OK to use as a loading cap in a final pi-tank coil, even if the amplifier in question was to be used in a (then) legal limit operation, AND plate modulated! 

Anyway, I'm happy to report that nothing has arced over thus far, and I have a QSO with VK3ZL (thanks, Rob!) in the log from this morning on 160-meters to prove it, Hi Hi.

Happy DX'ing & vy

~73!~ Eddy VE3CUI - VE3XZ