Frank,
I don't view this as an "either-or" situation. That is, BOTH our own
transmitters and these external non-linear distortion generators can be
causing the problem. When both are present, BOTH proper stub design/good
coax wiring AND finding/defeating the external non-linear distortion
generator are required.
It's the same old story of "peeling the onion" with multi-element
problems. You fix one element, allowing you to hear the other underlying
components that were obscured by the one you fixed.
Using the contesting trailer documented in k9yc.com/7QP.pdf, we had no
issues with harmonics when set up in the middle of nowhere, but DID have
issues with external distortion sources when set up within a half mile
or so of "civilization."
73, Jim K9YC
On 9/14/2017 10:13 AM, donovanf@starpower.net wrote:
Dave's reply is the only one that correctly addresses the problem
you described. You described your problem as " rise up floor noise
level about 60 khz on each side from main harmonic frequency."
Many contest stations -- including mine -- experience the exact
problem you describe, it has a name: "RF Flooding" Its caused
when a powerful RF signal penetrates a non-linear device that has:
- AC power or digital signals flowing though it, and
- is connected to wires that receive the powerful fundamental RF
signal and re-radiate broadband modulated harmonic RFI.
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