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Two tuned circiuts and a 1N34 Crystal Doide make this FM converter.
Input from left is from new FM antenna band. Output from right, is shielded output cables to antenna leads to FM frequency radio on different band.
All coils, capacitors and 1N34 diode are in metal case. All four coils are shown as two transformers for the simulator drawing. All coils are wound on 7/16 inch diameter form and space winding coils is about 1 diameter of wire spacing).
Left to right is coils L1, L2,L3, and L4.
L1 coil is 2 turns of #18 insulated hookup wire ( interwound with coil L2).
L2 coil is 4 turns of #12 enamaled copper wire space wound and supported on C1 (first capacitor from left).
L3 coil is 10 turns of #12 enamaled copper wire space wound and supported on C2 (second capacitor from left).
L4 coil is 3 turns of #18 insulated hookup wire ( interwound with coil L3).
Simply spread the coils on L2 to raise the frequency for local FM stations.
Four 10 u ohm resistors and two SPST switches are in bottom circuit to simulate and show stages of conversion.
Top circuit is drawing I started with and bottom is to use in simulator.
At first, left antenna source , the AC generator, shows 95 MHz signal of interest and not all other FM station signals that would be present at this point. L2 and C1 are tuned to 95 MHz. L3 and C2 are tuned to 65 MHz.
To run, first close left switch a few seconds to charge capacitors then open left switch. Note center is oscillating at 81.4 MHz, not 95 MHz (the blue waveform). Now, close second SPST switch a few seconds, then open switch to energize L4, the shielded antenna wire to lower frequency of 65 MHz ( press green line to display green waveform). The receiver tuning circuit is set for 65 MHz.
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