The Inrad filter has a center frequency of 9 Mc, therefore i had to re-design the VFO, BFO, LPF's on each of these and the IF bandpass filters before and after the high-gain IF amplifier module. Alot of work!
With all of this complete i was able to tune in local amateur radio stations with ease.
Next step the AF and TX audio. I used a dual audio power amplifier chip, one half for RX to speaker audio amplification, the other half for TX audio. I purchased a surplus Motorola microphone from the MIT flea market for $5, found the schematic on repeater builder, and with advice from Mike Volz i biased it up.
I fed the output of one channel of the audio amp through a 100 ohm resistor to the IF port of the product detector. Wired the PTT switch from the surplus Motorola mic to the TX line of the bi-directional IF amp. Using my PARTS radio, i was able to listen to myself transmit using the DIY 40M radio! Success!
Next step: design the AGC system, then build it.
Next step: design the TX driver/power amplifier assembly
Next step: design the front-end LNA and TX/RX relay assembly