2N2/15 Receive Strip Schematics

This is the latest version of the receive strip input section showing the input active r.f. mute switch, gain controlled r.f. amplifier, main double balanced mixer, and diplexer.

This next section contains the active crystal filter driver, 4 pole - 500 Hz crystal filter, active filter terminator #1, gain controlled first i.f. amplifier, fixed gain, tuned second i.f. amplifier, 2 pole - 500 Hz roofing filter, and active filter terminator #2.

Here is the third section containing the receive product detector, Rx audio mute switch (this may not be necessary), and Rx local oscillator.  The local oscillator is tuned above the passband of the crystal filter, so that the receiver is using the lower sideband for reception.  This was done to take advantage of the crystal filter's overall shape.

And the final section showing the audio phase splitter, push-pull audio output amplifier, and the somewhat complicated AGC amplifier.  The AGC amplifier also provides manual r.f/i.f. gain control, receiver muting during transmit, as well as some QSK shaping.