WQNR-FM 4CX3500A PA Tube Replacement and Transtector Installation – Sept. 13, 2021

The Eimac 4CX3500A Power Amplifier tube in the WQNR-FM Harris HT5FM transmitter was failing and had to be replaced. A recent lightning strike had also damaged a few devices including the panel-mount surge/transient protector.

Output from the WQNR-Harris FM HT5FM transmitter had dropped to roughly 35% due to the failing Eimac 4CX3500A PA tube.
“Soft” 4CX3500A tube pulled from transmitter. This tube had definitely seen a fair amount of heat over the years.
Cathode-end view of the soft 4CX3500A pulled from the transmitter.
New (rebuilt) Eimac 4CX3500A PA tube seated in tube socket. It definitely looks a lot nicer.
With the new tube in place and everything tuned up, TPO of the Harris HT5FM was restored to 100% or slightly better.
New IT Transtector installed in place of the old, lightning damaged surge/transient protector.