Discussion in 'Amplitude Modulation' started by N4WLL, Jun 27, 2021.
Looks like it supports the big rheostat in series with the +HV line, used to fine-adjust the PA plate voltage. I found that to be useless in my BC1-T, so I took it out, and replaced it with an 800Ω bank of fixed power resistors, which drop the PA plate from 2600v down to around 2300v. But keep the full HV on the modulator, increasing positive peak capability to around 140%. Very rarely hit that high, but now the modulator doesn't flat-top and splatter on those occasional peaks.
My bad, I shouldn't have been measuring at 2AM. They are 3" not 2¾.
That pot is there so the operator can try and keep the FCC output power between -10% and +5%.
Did you ever get around to mailing them? No hurry if you haven't, and I can pay for the shipping if you'd like.