For those interested in the Trio SM-301 here is some practical info from antique radios website.
Some details on operation.
Antique Radio Forums • View topic - Trio FM Stereo generator SM-301
Some details on operation.
Antique Radio Forums • View topic - Trio FM Stereo generator SM-301
I decided to test the original Neon lamp by removing it and connecting it to 120 VAC with a 100k dropping resistor. It lit dimly at first and more brightly as I wiggled the leads. I took apart the assembly by removing the lens carefully with some heat... and pushed the lamp through the lens opening. The wires had burned up or corroded so badly they fell apart almost immediately.
The lamp is stamped GE 2E.
I managed to attach enough lead wire to the lamp and put it into circuit temporarily. The original lamp will not light. Nor will a brand new 2E lamp.
The lamp is stamped GE 2E.
I managed to attach enough lead wire to the lamp and put it into circuit temporarily. The original lamp will not light. Nor will a brand new 2E lamp.
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Success - FM stereo indicator
Success. I have an FM stereo indicator.
It was a) the neon lamp that had perished and b) alignment. The lamp flickers as you tune into a strong stereo signal, and it flickers in sync with the demodulated audio signal. I don't know if this is normal or not, I was just happy to see it light up.
Consider where the lamp is in the circuit, I am not surprised that the voltage across the lamp varies, but I am no expert in FM stereo demodulation.
Franz
Success. I have an FM stereo indicator.
It was a) the neon lamp that had perished and b) alignment. The lamp flickers as you tune into a strong stereo signal, and it flickers in sync with the demodulated audio signal. I don't know if this is normal or not, I was just happy to see it light up.
Consider where the lamp is in the circuit, I am not surprised that the voltage across the lamp varies, but I am no expert in FM stereo demodulation.
Franz