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

[Joe Subich, W4TV]

> Of course, this is taken care of automatically in the PX3 :-)

Many of the better "SDR Console" software packages include a
configuration option to "swap I/Q above 'N' MHz" ... works for
KX3 on 144 MHz and K3 on 50 MHz.

73,

   ... Joe, W4TV


On 2014-11-03 9:41 AM, Matt VK2RQ wrote:
> 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
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