We are experiencing low to mid level constant headset noise only when our GAZ displays are connected to the Tdc8000.
We have set up our 8000 approx. 200 feet from the display board location. The cabling to our junction is 6 pair com. line and from the junction we have a cat5 cable ( approx. 50 feet).
In additional to this our entire system line which runs up the slope approx. 2400 linear feet is buried approx. 2 feet from the high voltage line for snow making. And we had to locate our junction for the display at the finish on the same pole as the high voltage connection for snow making.
We are thinking that the high voltage is probably causing the interference. It only occurs with the display connected. Are there any suggestions or possible tests that we can conduct.

I have experienced similar situation when the GAZ units are connected. My solution was to totally isolate my timer/pc/display by using different opto-isolators.

For the Timer we use the TAG opto-isolator just in front of the connections of the photocells and start gates into the timer. If you do this you will need a headset amp to sit in front of the opto box to be able to still talk down the start line. This is highly recommended if you live in low humidity area and have long cable runs!

For the Gaz units we use a RS232 opto isolator inline to break the ground connection between the computer/timer/pc and display. Works like a charm! This is probably your best test first. We use a box made by Black Box Australia and 2 9volt batteries to power each side of the opto circuit. Works great, batteries last about a week of solid use.

I'm sure Phoenix Sports has both these options in stock.

The ALGE Optodata is a powered optocoupler designed for theis purpose. It plugs into the timer and then the cable to the display plugs into it. It has a 9v battery inside.

ALGE Part # 916-01