Originally Posted by glebo
As stated by previous posters, you're most likely running into an "intermodulation" problem.
Can be caused by to close proximity with various systems, cables intertwined (Coax doesn't shield totally) especially if there's an amp involved. Can also be caused by freq's being to close together and developing harmonics.
Also as stated, antenna placement could also be involved.
Try re-routing cables, and a little separation if possible, that should reduce and maybe stop some of the problems.
I guess ya just gotta fiddle with it for results.
I agree with glebo.
In a high RF environment, there is going to be some direct pickup, or as us RF Spectrum guys would say. Brut force pickup.
Shielding of the systems cables can help a lot. EMI is a fun thing. Keep connectors clean, and watch you power out on all of the radio systems you are using. Use the lowest setting to talk in your net.
PS get this passed up the chain to the JSC, Joint Spectrum Center. document it all with a JSIR report.