[Elecraft] [K3] Aliases in Softrock panadapter display

[Stewart Rolfe]

Not sure where best to post this but will try here first...

I've set up my Softrock panadapter again using NaP3 this time. Works very well with my M-Audio PCI card (96Khz) and the WBIR is effective too. One thing I wonder about is connected with the offset between the IF and the SR local oscillator frequency.

The SR local osc runs at 8192 Khz which puts it outside any K3 filter passband. When I configure NaP3 with this frequency (and zero global offset etc) the K3 and panadapter display are exactly in sync and I can point and click etc. But the tuning point is naturally offset from the LO by ~23 Khz which means there's only about 25Khz 'usable' to one side of the tuning point in the display before it goes into alias territory (96/2 minus 23Khz...). Rocky seems to simply cut off the display at the sampling edges but NaP3 (and PSDR/IF?) doesn't and this can be a bit confusing when aliases are displayed.

This is easily worked around by for eg winding up the zoom to make the illegal band disappear, but it would be nice to be able to have LO and filter centre coincident. I notice that the background colour indicates +/- 48Khz but it's centred around the IF centre and not the LO frequency which would be better.

Hope I've explained myself OK..!

73,

Stewart, GW0ETF

PS It's all linked together with LP-Bridge in case that's relevant...