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;

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;

"Doug" wrote in
ink.net:

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


If you are ever near Ft Collins, Colorado, go bang on the front door of
NIST's WWV time stations, the frequency and time references for the world.
Those guys love to take techie touristas on a nickel tour of the plant.
WWVB on 60 Khz isn't as exciting as it was in the old days when they had
the massive antennas, though. Their 60 Khz antennas are more modern now
and don't flashover near as excitingly as they once did.
http://www.boulder.nist.gov/timefreq/stations/wwvb.htm
No, Gary, they don't have 1250 meter towers, which is the ELECTRICAL length
of 60 Khz 1/4 wave. They use loading so the electrical length is 5000
meters on towers with a PHYSICAL length of only 125 meters. The capacitor
hat is HUGE! They use three 38KW transmitters to get 50KW ERP from 3
phased antennas with about 57% efficiency. This greatly reduces the
electrical stresses on very high powered helix houses like Cutler's.

Hee hee....we should send Gary Shafer to Cutler so he can learn about the
electrical length of an antenna being different from the physical length of
an antenna with loading coils and capacitor hats....(c; The electrical
length at that freq is a hair over 5 miles for a simple dipole...(c;

You should see the rhombic antennas at NW Cape, Australia the Navy has run
for years near Canarvon. The locals are so afraid of the flashovers they
won't go anywhere near them!...(c;

Larry W4CSC
POWER IS OUR FRIEND!

On Wed, 28 Apr 2004 13:03:51 -0000, Larry W4CSC
wrote:

"Doug" wrote in
link.net:

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


If you are ever near Ft Collins, Colorado, go bang on the front door of
NIST's WWV time stations, the frequency and time references for the world.
Those guys love to take techie touristas on a nickel tour of the plant.
WWVB on 60 Khz isn't as exciting as it was in the old days when they had
the massive antennas, though. Their 60 Khz antennas are more modern now
and don't flashover near as excitingly as they once did.
http://www.boulder.nist.gov/timefreq/stations/wwvb.htm
No, Gary, they don't have 1250 meter towers, which is the ELECTRICAL length
of 60 Khz 1/4 wave. They use loading so the electrical length is 5000
meters on towers with a PHYSICAL length of only 125 meters. The capacitor
hat is HUGE! They use three 38KW transmitters to get 50KW ERP from 3
phased antennas with about 57% efficiency. This greatly reduces the
electrical stresses on very high powered helix houses like Cutler's.

Hee hee....we should send Gary Shafer to Cutler so he can learn about the
electrical length of an antenna being different from the physical length of
an antenna with loading coils and capacitor hats....(c; The electrical
length at that freq is a hair over 5 miles for a simple dipole...(c;

You should see the rhombic antennas at NW Cape, Australia the Navy has run
for years near Canarvon. The locals are so afraid of the flashovers they
won't go anywhere near them!...(c;

Larry W4CSC
POWER IS OUR FRIEND!


I see you still haven't read any basic AC theory yet.

Ask them what the radiation resistance of those antennas are. :)

No Larry, the coil still doesn't tune the antenna or make it any
longer. It just cancels out the reactance of the antenna.

Regards
Gary Who is still trying to get Larry to open a book.

Larry,
The US Navy pulled out of NW Cape years ago. It is manned entirely by
Australian forces since about 1980. The US techs there took a lot of teasing
about being replaced by Australian females. NW Cape was on of our
terminating points when I was on Diego Garcia in 1979-80. Great DX as VQ9DM.
Doug K7ABX
"Larry W4CSC" wrote in message
...
"Doug" wrote in
ink.net:

You should see the rhombic antennas at NW Cape, Australia the Navy has run
for years near Canarvon. The locals are so afraid of the flashovers they
won't go anywhere near them!...(c;

Larry W4CSC
POWER IS OUR FRIEND!

"Doug" wrote in
link.net:

Larry,
The US Navy pulled out of NW Cape years ago. It is manned entirely by
Australian forces since about 1980. The US techs there took a lot of
teasing about being replaced by Australian females. NW Cape was on of
our terminating points when I was on Diego Garcia in 1979-80. Great DX
as VQ9DM. Doug K7ABX

Oh, oh....I've exposed my age, again....hee hee.

Most of the sailors were glad to go home....(c;