[TowerTalk] station to station interference

[Joe Subich, W4TV]

If they're Flex rigs do they have internal preselectors and are the
preselectors engaged when you experience the "interference".  Without
preselection, the *fundamental* one or more bands away can overdrive
the analog to digital converter causing all sorts of nasty issues.
It's even more likely if you have multiple active transmitters and no
front-end filtering.

73,

    ... Joe, W4TV

On 9/27/2016 8:36 PM, Jim Brown wrote:
> On Tue,9/27/2016 5:17 PM, Steve NR4M wrote:
>> Any guidance on what I should be looking for would be of great help.
>
> Hi Steve,
>
> What radios and amps?  Some are a lot cleaner than others. The
> interference you describe sounds like it could be phase noise. The
> TXNoise collection of ARRL Lab test data (on my website) is a good place
> to see differences between rigs on TX. That data is several years old.
> Since then, new firmware has improved the FTDX5000 and others in that
> line, the new synth board designed for the K3S is about 10 dB better on
> phase noise on both TX and RX. The Flex rigs didn't test well, but Flex
> issued new firmware that, I'm told, improved it significantly. But I
> can't get one to measure. I DID measure an FTDX5000 and confirmed the
> improvement. Data is on my website.
>
> Could one of more of the amps be overdriven, or otherwise behaving
> badly? Good chokes on all antennas at their feedpoints?
>
> 73, Jim K9YC
>
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