I may be wrong here, but I recall a lot of problems on Mt. Wilson, and other sites, to broadcast 940 MHz STL's as well as VHF radios from Quintron paging transmitters.? As I recall, it was when drive was removed from them that they would oscillate in the final stage.? The cure was to remove the amplifier's voltage when they were supposed to be off rather than leaving the amplifiers powered up and simply removing drive.
Burt, K6OQK
Burt K6OQK