MCC5500 with APX 8500 mobiles in a tray- odd issue with transmissions mixing

[KB9_911_SDA]

We have a strange issue that just started with our MCC5500 consoles. Wondering if anyone else has encountered this or knows a fix. Our radio vendor has never run into this issue before. He has tried a couple of things to fix the issue with no luck. He has contacted Motorola directly about the issue and is awaiting a reply.

I am impatient so I came here to see if anyone could help.

We have three CABS/software installs. We have five 800 MHz APX 8500 mobiles in a tray and a couple of older VFH radios in our CES. They have all been working fine for the last year.

Recently we began having the following issue:

When two dispatchers, at two separate consoles, are transmitting on two different 800 MHz talk groups at the same time field units are hearing it as if both dispatchers are transmitting on the same talk group. It also sounds like the signals are mixing together so that neither transmission is fully understood.

Our vendor looked at some settings in our CSDM, he powered down the CES several times and he moved a couple of radios around to different spots and so far none of that has worked.

 

[RFI-EMI-GUY]

Is this an analog 800 MHz system..?

If so it sounds like your control station / mobile radios are overloading a nearby receiver site. Creating an inter mod product. Generally where there are RF controls used for dispatch, care has to be taken to prevent this. Reduced power, antenna isolation either physically or electrically. Antenna Specialist made a device called a Varilator that provided some power reduction and isolation. Another company made a pricey multicoupler to combine many RF controls onto one antenna.

What has changed recently? Has anything been "fixed"? Any work on the roof? Did the power get adjusted on these radios to fix another problem? Is this mixing limited to only one talk group or do others complain of hearing these dispatchers?

 

[Tech21]

Is cross muting between the consoles set up correctly? Is cross muting between the radios set up correctly? What is the power output of the control stations? Are these radios working off of mag mount antennas shoved in the roof or are they connected to antenna's outside of the building? If they are on mag mounts, one of your antennas or lines is bad, have your vendor put a wattmeter in line to check forward and reflected power on each radio.

 

[jeepsandradios]

Duplicate ID ?