I have had a tour of the transmitters and antennas at US Navy transmitter
site at Cutler, Maine where they run up to 3 MW output power at 17.6 KHz.
They replace elements in the tubes and pump the vacuum back down. The helix
coils at the antenna feed are massive. When ice starts to load down an
antenna array, they put AC power through the antenna to ground so the
antenna wire heats up and sheds ice.
Doug K7ABX

"Larry W4CSC" wrote in message
...
Bruce in Alaska wrote in
:


Had a Gates 15Kw FM take a dump, from over the hill Power Tubes going
flat at 2AM in the snow. Back of the Cabinet was outside building
with the front inside. When I arrived, with the consulting engineer,
we found "Smoking Holes in the snow" where the final parts had been
thrown, and melted down thru the snow. This was a NON-Profit,
noncommercial, that used handmedown finals from the local Tv Station
Modulator, and when they went south they did it in an "Exlosive"
fashion. It took us 6 hours to rebuild all the "Plumbing" and get
back on the air with the next set of "Overtime Tubes". One of my
many "Broadcast Stories" from when I was a kid.


Bruce in alaska

One of my friends, and a great RF technician, just took a job with the
local Fox UHF station, the most powerful (5MW ERP) broadcast transmitter
in
SC. It's a big RCA with two 8' tall boiler klystrons putting out
something
like 180KW into 6" rigid up the tower with the usual diplexer. They "run
it until it blows" because the klystrons are amazingly expensive,
something
like 30 Grand each. The tubes they have are all WAY over their MTBF hours
and they keep cranking up juice on them to keep them within output
tolerance.

I don't wanna be anywhere near the beasts when the focus magnets finally
open and the beam through the cavities at 25KV at 10 amps
comes.....well.....unfocused on the copper block collector....(c;

Larry

He's already experienced some amazing flashovers and brought me some
souvenir ceramic insulators from the big power supply....(c;