So after I finished my "what if" redesign of a power supply board, I decided to try and do the same with the receiver panel in this board set.
Most all the parts should be fairly straightforward to change to SMT (I may want to see if there is a suitable substitute for the CA3140 op-amp, tho').
Anyway, I ran into a problem with the two tank circuits on this board.
Both tank circuits are the same: a 6800pF film capacitor paralleled with a 22mH variable inductor to peak the signal response at 12.5kHz.
I have options as regards the 6800pF cap, no problem, but it unfortunately seems that, AFAIK, the 22mH variable inductor is obsolete.
Assuming I want to try selecting different values (giving priority to inductor value selection), how would I go about finding other values that would work just as well to give me a tank circuit with f = 12.5kHz? (no calculus, please)
Most all the parts should be fairly straightforward to change to SMT (I may want to see if there is a suitable substitute for the CA3140 op-amp, tho').
Anyway, I ran into a problem with the two tank circuits on this board.
Both tank circuits are the same: a 6800pF film capacitor paralleled with a 22mH variable inductor to peak the signal response at 12.5kHz.
I have options as regards the 6800pF cap, no problem, but it unfortunately seems that, AFAIK, the 22mH variable inductor is obsolete.
Assuming I want to try selecting different values (giving priority to inductor value selection), how would I go about finding other values that would work just as well to give me a tank circuit with f = 12.5kHz? (no calculus, please)