Re: Suggested Change for VFO: Additional BandStops #bpf #vfo

Steve KA6PRW

Just to be clear:  The change that I am proposing would 'copy' the current "11 Band LPF" addition that is documented and used on the U3S today (11-band U3).

The U3S scheme uses one of the 'aux' bits to select the LPF relay board.  This bit is multiplexed and there is a circuit already proposed and tested, in the same document, to 'filter' the 'aux' bit for use in this new functionality.

All the 'BandStop' settings, both current and the proposed new 'BandStops', would have to incorporate into the user interface, a way to set the 'aux' bit, like is already done in the presets. I do not think this would be difficult.

I have already implemented the U3S modification, for the 11 band LPF, and it works as suggested in the modification document on the web site. 

As I said in the original request, two other options to make this happen are to simply always use 'Presets' as they already have the 'aux' bit functionality (which is 'kludgy' and fairly labor intensive, or, an alternate, although not so glamorous method, is to use a switch that could be used to select between one LPF relay below say 30MHz and the other above 30 MHz.

I think this is fairly straight forward and basing it on the current U3S 11 band modification, the implementation should be relatively straight forward.

I may be wrong - Hopefully this clears up my original intent.

Steve Jones KA6PRW.

On Tuesday, April 3, 2018, 9:49:18 AM PDT, Daniel Ekman SA2KNG <knegge@...> wrote:

Basic problem with the request is that it doesn't contain a suggestion on how the hardware should work.
I'ts certainly not impossible, just that it has no simple solution that doesn't have the risk of impeding on other functionality. There ain't too many "spare" pins available. There will be only one firmware, so all accepted features are implemented and then you change some parameter in the menues that selects the behaviour you want.
For example; If you want one more pin for multiplexing (bank a/b) it will probably come from this list: gps data, gps pps, button 1+2, encoder a+b. If you choose one of them, what protects them from getting toasted if someone configures it wrong ?
Another way of doing it would be to steal the first relay and make that multiplex 5x2 relays, add some 10 additional diodes and wiring.
And a quite different way would be to use an external shift register and repurpose the relay pins to go to one or more of these in cascade. This requires another board to be inserted between the qcu and the relay boards as to decocde/drive these.
The next problem is figuring out which one of these will be best for the future and then sticking to it. It needs to be compatible and safe for current and future hardware.

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