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Thanks for the suggestion John. I use one of those SAW transmitter modules, but it is built to be CW modulated, meaning all or nothing. The modulation input drives the base of a transistor through a resistor that is in series with the ground connection of the emitter of the oscillator transistor. You could apply a potentiometer between the positive supply and ground and vary the conduction of the modulator transistor linearly. This would fundamentally vary the amplitude of the oscillation and perhaps the frequency somewhat, but you would have to be careful not to completely turn off the oscillator. I suppose there would be the possibility of using a module prepared for FM or adding a varicap to it somewhere in the current one, but with a 3V3 power supply it would not do much. It is much easier to measure the frequency of the module with a frequency meter and write it down and correct the value of the IF in the TinySA when it is going to wobulate. As the minimum RBW is 3kHz I do not consider necessary a GPS type precision. Also, I assume these SAWs are not very accurate, but they are stable. I mean if mine is offset by 22kHz, I trust it will stay at that value over time and not vary several kHz with the shack temperature either. This low power value is also a drawback when feeding the MAR-8A as it is specified for 3V6 and when feeding it with 3V3 I deduce that its gain and its maximum output level drop appreciably, as has the consumption (from 36mA to 14mA ). And thank God that this new version of the MMIC works at 3V6, because "the old one" did it at 7V5.

Greetings to all and thanks again