09-02-2025, 06:44 PM
Hi RGK,
I think that the 120 pF may work. It is not exactly a tuned circuit; it is cap coupling to a diode for the purpose of generating a DC voltage. Pulsating, just like that audio, but smoothed by the RC circuit (C#23, R#15). If a VTVM would load it down, try an O'Scope. I seem to remember (maybe correctly, maybe not...) that an RCA schematic stated to use a Channelyst or Voltohmyst (RCA brands of VTVM). I am a little surprised that a DVM or VTVM would load it down. If a DVM is 10 MOhm/V, at 10 V, isn't the impedance 100MOhm? Alternatively, install a "tuning eye" tube. They work of the AVC line, I believe.
Definitely try a longer antenna. If possible, stretch a line outside your house and use a water pipe or made ground.
I think that the 120 pF may work. It is not exactly a tuned circuit; it is cap coupling to a diode for the purpose of generating a DC voltage. Pulsating, just like that audio, but smoothed by the RC circuit (C#23, R#15). If a VTVM would load it down, try an O'Scope. I seem to remember (maybe correctly, maybe not...) that an RCA schematic stated to use a Channelyst or Voltohmyst (RCA brands of VTVM). I am a little surprised that a DVM or VTVM would load it down. If a DVM is 10 MOhm/V, at 10 V, isn't the impedance 100MOhm? Alternatively, install a "tuning eye" tube. They work of the AVC line, I believe.
Definitely try a longer antenna. If possible, stretch a line outside your house and use a water pipe or made ground.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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