[Elecraft] [KX3] RX I/Q signals "reversed" on 2m

[Matt VK2RQ]

That's interesting, the RX I/Q signal lines appear to be "reversed" when operating the KX3 on 2m.

I guess this makes sense, if you consider the 2m module is using the "x4" output of the KX3's local oscillator, so that if you tune to 144MHz for example, the LO would be running at 48MHz, so that in the 2m module the 144Mhz signal would be mixed with a 4x48=192MHz signal. This would place the "USB" image at 192+144=336MHz, which is discarded, and then place the "LSB" image (192-144) at 48MHz, which is then downshifted to 0MHz by the 48MHz LO in the main receiver. Because the LSB image is the one that is used, the frequencies appear "reversed" when you look at then on the I/Q output. By swapping the I & Q signals, you can effectively "reverse" the frequencies a second time, and get a normal display on the waterfall. Of course, this is taken care of automatically in the PX3 :-)

73,
Matt VK2RQ