Current situation: the MD59LS has been converted to a 9600 Baud packet transceiver. Audio for modulation is applied to the 21.4 MHz crystal oscillator. A pll locks the vco, around 452 MHz. The same vco signal is used as LO for the receiver. First mf of the rx is also 21.4 MHz. With a 20.945 MHz crystal this is mixed to the second mf of 455 kHz. Via the 455 kHz mf filter the signal reaches the demodulator TDA1576, tuned at 455 kHz. ...