11-24-2015, 01:16 PM
Looking at the plate of the 1st audio tube, it's strange. Inputting a sine wave at the volume control, I get a soft rolloff of the bottom of the waveform, while the top remains sinusoidal. When listening to an actual radio signal, if the volume is low enough, the waveforms are reasonably good (likely as good as I'm likely to get on AM these days), but if I turn it up even a little higher, the tops of the waveforms drop off in a fashion similar to a sawtooth wave, |\ Obviously the bias is NOT in the sweet spot, but taking voltage readings on the plate and screen grids, I get ~76 and 55, respectively.
Any idea what the grid voltage on the 1st audio should be? I'm getting around -2V.
AGC is getting better. In fact, I can get a good signal on a short wire with reasonable control, but if I connect my longwire it will overload like crazy when tuned to my in house AM transmitter. I'm getting -5 AGC on the RF amp, and around -3 on the 1st IF on a strong signal. I did find a wiring error on the volume control that once corrected made quite a difference in performance.
Any idea what the grid voltage on the 1st audio should be? I'm getting around -2V.
AGC is getting better. In fact, I can get a good signal on a short wire with reasonable control, but if I connect my longwire it will overload like crazy when tuned to my in house AM transmitter. I'm getting -5 AGC on the RF amp, and around -3 on the 1st IF on a strong signal. I did find a wiring error on the volume control that once corrected made quite a difference in performance.