22-05-2022, 07:46 PM
Basic ways a ferrite rod aerial connects
1: FET or valve input.
2: bipolar transistor or old radio IC. Might use four wires.
3: AGC to valve or FET is usually decoupled at RF by a capacitor.
4: AGC to BJT or IC is usually decoupled at RF by a capacitor.
Not shown is the ZN414 IC. It's a variation of 3.
1: Could be a crystal set with crystal, ceramic or 4K Ohms headphones.
2: Could be a crystal set with 600 Ohms if you want more Q at expense of volume.
Just wire the LW coil from any transistor set as per the MW coil, via the bandswitch. If it needs to be version 4 rather 2 simply overwind 20 turns.
Peak at 198 kHz by moving coil in/out at end of rod. If it's not peaking on the rod then it's too few turns. If too much needs to extend past the end, then it's too many turns, but if it gets 252 kHz and 198 kHz then don't worry.
It may be be possible to connect it up without taking off scale cord etc.
Typically any external aerial uses about ten turns on main ferrite.
