11-18-2023, 09:32 AM
I presented this specific problem on the other forum, but have failed to get a response so far:
The radio has been recapped, and resistors replaced. The SW and Police band antenna coils and oscillator coils have been removed. The broadcast oscillator coil has been replaced by a Miller 70 osc. So this radio is now single band. The original schematic is below, followed by the wiring changes I made. I get strong IF oscillations at 450 KHz from antenna to speaker. The problem is RF. By using the osc. padder, trimmer, and coil slug on the Miller 70, I can adjust it so I receive RF from about 1150 to 1650, but nothing below. By re-adjusting everything, I can get 600 KHz, but only with the tuner set around 1300 on the dial, and then, of course, I lose everything higher. None of the blades on the tuner short out. The padders and trimer are both good. I assume I'm getting negative voltage on the grid of the 6A8, but whenever I touch my meter (both VTVM and digital) to the pin, the radio stops oscillating, and it shows 0 volts. Where do I go from here? Can't find another oscillator.
[Image: https://i.imgur.com/SY9vkEh.jpg]
[Image: https://i.imgur.com/hNBYcTf.jpg]
The radio has been recapped, and resistors replaced. The SW and Police band antenna coils and oscillator coils have been removed. The broadcast oscillator coil has been replaced by a Miller 70 osc. So this radio is now single band. The original schematic is below, followed by the wiring changes I made. I get strong IF oscillations at 450 KHz from antenna to speaker. The problem is RF. By using the osc. padder, trimmer, and coil slug on the Miller 70, I can adjust it so I receive RF from about 1150 to 1650, but nothing below. By re-adjusting everything, I can get 600 KHz, but only with the tuner set around 1300 on the dial, and then, of course, I lose everything higher. None of the blades on the tuner short out. The padders and trimer are both good. I assume I'm getting negative voltage on the grid of the 6A8, but whenever I touch my meter (both VTVM and digital) to the pin, the radio stops oscillating, and it shows 0 volts. Where do I go from here? Can't find another oscillator.
[Image: https://i.imgur.com/SY9vkEh.jpg]
[Image: https://i.imgur.com/hNBYcTf.jpg]
