[Elecraft] KX3 - UHF emissions

[Matt Zilmer]

You might want to enable the isolation amp in the KX3's RX.  That
setting can be accessed in the MENU as RX ISO.  Not sure this will
solve your problem, but it might make it a bit better.  If the spurs
were radiating through the antenna, it definitely would help.

73,
matt W6NIA

On Tue, 24 Jun 2014 20:00:52 +0100, you wrote:

>Hi,
>
>I've noticed that my pair of scanners often receive strong spurii from my KX3's
>receiver, in the UHF mil air band.  Whilst the spurii can be detected faintly
>with no cables attached to the KX3, when I attach certain cables, the strength
>of the spurii increase, most notably the I/Q cable, which causes (what passes
>for) the S-meter on the scanner to fully deflect. Connecting an antenna to the
>KX3 doesn't seem to have any effect.
>
>The other day I noticed that my scanner had stopped on a locally used UHF
>channel that was exactly 100 times the frequency in the 80m band that I was
>listening to.  Today I have noticed that listening on 7.08Mhz SSB, my scanners
>stop on 389.4Mhz, which seems to be the 55th harmonic of the KX3's dial frequency.
>
>This is affecting my AOR-8600mk2 and IC-R20. Unfortunately, I've also been
>developing a hybrid spectrum sensing scanner (called Onsense), that uses a
>HackRF to sample the mil air band and tune in my AOR-8600mk2 to the strongest
>signal detected.  I find that I am constantly having to add frequencies to
>Onsense's blacklist as I tune my KX3.  This isn't a good situation to be in.
>
>I already have a ferrite on the I/Q cable, but that doesn't help.  When I enable
>the 8kHz shift on the KX3, the previously detected spurii goes away.  Whether it
>goes entirely or not, I don't know, it may just shift to another frequency that
>isn't being scanned.  The RX Isolation filter is enabled.
>
>Is anyone else having similar problems? Is this normal for a KX3?  Is there
>anything I might try to mitigate this?
>
>Cheers,
>
>Darren, G0HWW
>
>
>
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Matt Zilmer, W6NIA
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