Re: Pizza's Transmitter Build
OK, good progress so far. What I learned today: The Balance modulator loss is 14 dB. More than I think is right, but the prefilter amp is giving me 12-14 dB gain so I guess we are good. I know what current I need at 320 volts to operate the oscillator and prefilter amp. ( see schematic diagram below)
The filter sure works, I am driving the spectrum analyzer with the output of the filter, note how on the right side of the spike, there is no signal, that is the upper sideband, only the lower sideband is present. Mic audio is from my PC speakers playing a Youtube video with my transmitter mic gain wide open. (See picture with underside of transmitter and spectrum display)
I expected a challenge and this has been that. I believe I started construction around December 17 but serious work started on Christmas weekend. Making accurate measurements of gains and losses is a challenge, as my test equipment is 50 ohm input, and these are high Z tube circuits running between 400 and 10,000 or more ohms.
Last edited by pizzaguy; 01-27-2024 at 07:46 PM.