12-16-2013, 10:20 AM
Bret;
Mondial is right. That capacitor is in series with the rest of the caps and the coils in the circuit. As such, it will affect the tuning of the associated parts. Using film type capacitors in RF circuits is not a good idea as the internal parts are coiled up, thus creating an inductance, so you have not only changed the capacitance but the inductance as well. Use the 2000pFd silvered mica replacement and try aligning again. An alternative would be to use a NPO type 2000pFd disc ceramic capacitor. Disc ceramic capacitors and silvered mica capacitors have minimal inductance internally and that is just one reason why you see so many of them used in RF and IF circuits.
Good luck!
Joe
Mondial is right. That capacitor is in series with the rest of the caps and the coils in the circuit. As such, it will affect the tuning of the associated parts. Using film type capacitors in RF circuits is not a good idea as the internal parts are coiled up, thus creating an inductance, so you have not only changed the capacitance but the inductance as well. Use the 2000pFd silvered mica replacement and try aligning again. An alternative would be to use a NPO type 2000pFd disc ceramic capacitor. Disc ceramic capacitors and silvered mica capacitors have minimal inductance internally and that is just one reason why you see so many of them used in RF and IF circuits.
Good luck!
Joe
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