It was OK with the tubes removed but no test equipment, but when I set up for the tests it acted strangely when bringing up the Variac. Usually when I switch on the Variac that feeds the radio power supply the beginning voltage is about 0.4 volts and it increases very rapidly as I turn the dial...
Did you see that instead of re-installing the 216 varicaps I placed a fixed value 22 pF cap across those three RF stage coils? With that value and up to an additional 10 pF from the trimmers I should be able to receive 126 MHz as my test RF. I am going to modulate it with a 1 kHz test tone.
So...
I was just getting set up to do the tests and removed the VTs for the harmonic generator and harmonic oscillator to disconnect those stages. When I brought it up to power, I detected a bit of electrical smell and immediately shut down. I replaced the 9002 and 9003, re-powered, and now all is...
The 216 and 217 mechanically variable capacitors have been removed and would be a pain to reinstall. Can I put a fixed value capacitor across the coils, selected to approximate resonance at the calculated inductance of the coil and use the 218 trimmers to adjust? For the RF coil I estimate an...
OK, very good. What should be the range of the RF signal input at the front end as AVC is measured? A few microvolts up to one volt? Should the LO be set to the same signal level as the carrier? To which coil should I apply the carrier signal?
My multimeter has a 7.8 MOhm input impedance. Do I just use 11/7.8 as the multiplier? What should I use as the source of the low impedance reference voltage?
Many thanks for your reply! I am finishing the power supply for the receiver so I can make some tests. I have cleaned and deoxidized all of the tube pins and sockets after testing the filaments for continuity and applied voltage to the heaters and they all glow. Once I have the B+ voltage online...