The most important upgrade would be frequency agility on both transmit and receive.?
A 10 kHz shift would be great but even 5 kHz would be something.?
There are so many cases where you could potentially make a contact but can't as the station calling is on a different frequency to yours.?
You can do a lot with two crystals in parallel.
You could cover frequencies above the crystal with no inductance and very small series capacitance.?
For example in the video I got 10 kHz shift above the crystal frequency with the small capacitance formed by my unsoldered joint. And for coverage below you could have an RF choke or two in series with the crystal. This could be a plug in arrangement similar to the crystal but where you swap a wire link with an RF choke for lower frequencies.?
