mitaux8030
Silent Key
There's a modified MTX9250 (33cm ham) sitting on the bench here that I'd like to modify the IF bandwidth of. This won't be as simple as pulling the 450/455 kHz ceramic filter in the 2nd IF and replacing it because there is no 2nd IF as we traditionally know it.
Motorola has implemented a 2nd IF and demodulator on one chip, with the ability to program the IF filter width by serial interface from the radio's microprocessor, according to the service manual blurb. Does anyone have any detail on how this '32D83' IC works? I'm wondering if the C1P-C4P and corresponding C1M-C4M pins (pins 33-40) of that chip form some sort of switched capacitor network that achieve selection of IF bandwidth - and thus if the capacitors fitted externally to the IC on those pins will have an influence on IF bandwidth?
Motorola has implemented a 2nd IF and demodulator on one chip, with the ability to program the IF filter width by serial interface from the radio's microprocessor, according to the service manual blurb. Does anyone have any detail on how this '32D83' IC works? I'm wondering if the C1P-C4P and corresponding C1M-C4M pins (pins 33-40) of that chip form some sort of switched capacitor network that achieve selection of IF bandwidth - and thus if the capacitors fitted externally to the IC on those pins will have an influence on IF bandwidth?