Whilst playing with the 10FT8R something occurred to me. With FT8, oscillators only have to be stable over 15 seconds. Many free running HF oscillators are far more stable than this even long term.
So, I think the crystal can be replaced by a just a tuned circuit making this receiver work on any HF FT8 frequency. All that really matters is reasonable long term stability and good short-term stability. All that's required is to scale the RF tuned circuit (one tuned circuit) and set the oscillator to half the FT8 frequency needed. I have not tried this but cannot see why it should not work.
This may work as high as VHF where I have made free running oscillators work even on 2m.
Do not be afraid to experiment!
This should make the whole receiver very low cost indeed. It would not surprise me if many can make the entire RX for less than the cost of one coffee out.
Another option with frequency stability between a crystal oscillator and a free running oscillator would be using a ceramic resonator.
ReplyDeleteI recall VK3YE using this in a regenerative receiver, and a corresponding transmitter.
As you say, don't be afraid of experimenting.
Vy 73 de Jan, OZ9QV.