Idea Box : Multiband QRSS receiver.

This idea is from some years ago, when the QRSS frequencies were (mostly) harmonically related.

Today I would probably use a SI5351 (3 output clock generator) as local oscillators for three receivers.

From 2009 :
This could be extended to 3 or 4 bands with some effort, but here is the basic idea :

I have some Crystals on 3500 , 7000 and 14000 kHz. This could make for an easy setup of a dual band grabber using a single local oscillator :
Here is the trick : 
- make a single oscillator on 3500 kHz - use two buffers (possibly use the gates as buffers)- take one signal and use a direct conversion receiver circuit on 3500kHz, using the crystal filter of Joachim's QRSS receiver
- take the other signal and use the 3500 kHz LO signal for a receiver almost exactly as PA1GSJs receiver, 
- making it a *simultaneous* dual band grabber receiver for :- 3500.800 - 3500.900 kHz- 7000.800 - 7000.900 kHz
Of course, the same idea could be used to make a 7000 / 14000 kHz dual band grabber receiver using 7000 and 14000 kHz Crystals.
There is even the option of making a doubler for the 3500 kHz signal, using this for extending the dual band grabber to a 3-band grabber for 3500/7000/14000 kHz.
Actually Joachim and I have been talking about the 3-band idea, but I have come to think that the 2-band idea is better in terms of simplicity of construction