01-02-2024, 10:07 AM
(This post was last modified: 01-02-2024, 10:13 AM by Mike Watterson.)
I see it's got no RF amp, just a FET buffer, and simply select on test for the ferrite rod tuning cap. A LW radio aerial coil on 4″ or longer rod and about 7x the normal fully closed tuning cap to approximately tune. Fine adjustment can be with a polycon tuning cap and/or moving coil to end of rod.
So fit a coax socket at C3 100nF and feed 100 Ohms from R1 to that point for supply (optionally via a 10mH to 100mH choke instead of 100 Ohms).
Put a coil & cap (tuned to 60 kHz) and FET source with fixed 2K2 decoupled with 100nF. Then drain to coax. The box can go on a windowsill top of cabinet or outdoors.
At 60KHz the FET has adequate input impedance as an amp rather than a buffer.
So fit a coax socket at C3 100nF and feed 100 Ohms from R1 to that point for supply (optionally via a 10mH to 100mH choke instead of 100 Ohms).
Put a coil & cap (tuned to 60 kHz) and FET source with fixed 2K2 decoupled with 100nF. Then drain to coax. The box can go on a windowsill top of cabinet or outdoors.
At 60KHz the FET has adequate input impedance as an amp rather than a buffer.
