Ray
If you have no idea how the Harris DX series works, why are you posting a load of hogwash and rubbish??
Plenty of articles online explaining it.
The amplifier modules are enabled/disabled by the modulation system, thousands of times a second depending on the instantaneous power output required. The required power is calculated 648,000 times each second. Assuming the max mod (audio) frequency is 7.5khz, then the number of amps (there are 64 of them) in use will change 7500 times per second. Nothing to do with VSWR or temperature. A fault with VSWR or temperature will cause the control system to reduce total power output - which is achieved by reducing the number of modules in use, but that is not the main purpose of controlling the modules.
"backplane problem" sounds like a fairly common issue on the DX series of high resistance leakage on some of the multipin ribbon cables and connectors. Need a complete stripdown of the backplane boards and replacement of the connectors. Several days work on a decent workbench for a skilled engineer.
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