In the 1990s, Econco tried to rebuild a Machlett LPT44, a 150 kV glass
switch tube (triode) for us. It came back a bit lopsided, but we tried
running it, and all I remember is the technician at our klystron test
bench said come see the gold fish tank. They raised the tube up out of
the oil tank, and the entire tube was full of oil! That ended attempts
to rebuild these particular big glass tubes. Brookhaven National Lab had
more success rebuilding some ITT/Federal glass/metal switch tubes and
depended on Econco for decades to keep their Continental HV modulators
going. I am not sure what they are planning to do about it now, although
Fermilab had similar tubes and discontinued using that piece of
equipment, so its possible their old tubes and spares went to BNL if
they were same type.
For all who say tubes are dead, that CPI (now MPP) is going to go the
way of the dinosaur, you need to realize that they are not doing that as
they have a significant military and scientific market that isn't able
to just buy a solid state transmitter. Consider the HAARP site in
Gakona, Alaska. They have about 90 transmitters, each one with a push
pull pair of 4CW10,000D. Consider Fermilab's main injector ring, uses a
large quantity of a special version of the 4CW150,000E. That machine is
not going away, in fact there is a significant upgrade called PIPII that
will replace their linac from Photonis/Burle tubes to solid state but
their ring will continue with tubes. I was in a design review last week
with Brookhaven National Lab, which has just shut down their
Relativistic Heavy Ion collider after 20+ years of use, and is designing
replacement with EIC, the electron ion collider. It has significant new
RF power at 24, 49, 98, 197 and 591 MHz, both tube and SS amplifier
systems. The tubes are 4CW150,000E and RS2058 tetrodes. GSI in Germany
is building FAIR and their synchrotrons also use big tubes, TH555A and
others. Michigan State's FRIB machine uses the TH555A and TH781
tetrodes. We (LANL) use TH555A tetrodes, TH781 tetrodes, and TH628L
Diacrodes and are investing in a major upgrade that will replace some
accelerating hardware but continue to use the RF power plants that I
have worked on for 34 years. None of these machines are shutting down,
as governments and academia continue to invest in their science. Most
facilities are tooling up for the long haul, 20-30 years into the
future. They would not be doing this if MPP and Thales were hanging on
by a thread in the RF tube business.
So the loss of ham market, the loss of broadcast (don't forget the rest
of the world cannot always afford to buy a Nautel FM rig just to reduce
operating cost), does not mean that tube companies have a reason to
close up. I didn't mention military as I have less knowledge of it, but
I know there are a lot of special tubes there also, and they cannot be
designed out of equipment as it must continue running 24/7.
Also, a slight detour from this tube talk:
"FM broadcast went SS back in the mid 70's. AM broadcast went SS in
the late 70's. The later broadcast PA's that went SS, there was and
still is NO market for used tube broadcast PA's. The tube Pa's went
straight to the landfill ...... including tubes."
Broadcast FM didn't really have reliable SS rigs until DMOS and later
LDMOS were available. In the 1970s the biggest bipolar junction
transistors for 100 MHz CW were about 150 watts/300 watts PP. NHK, the
Japanese broadcast company, used early Hitachi DMOS transistors in a
complete 10 kW FM rig, in a paper presented at a IEEE broadcast
symposium in Washington DC in 1980. I was there. This was what
kickstarted Harris, Broadcast Electronics, Continental, Larcan, R&S,
Seimens, and other manufacturers to adopt DMOS parts from Motorola at
the time, derivatives of the MRF150 and push pull MRF151G. Those 151G
are the closest thing to 6146, as they continue to be made in quantities
by several companies (for science and broadcast). But to get beyond 600
watts (MRF154) it took LDMOS, again from Motorola, and now they and
Ampleon make 1.8 kW PP parts for class C. Burle Industries in Lancaster,
formerly the huge 1 million ft^2 RCA tube factory, is still in business.
They were bought by Photonis in France years ago, and continue to build
some tubes, for science and industry, but very little broadcast market
since they never penetrated the AM/FM transmitter business like Eimac
did in the 1980s. One of their very special tubes is the Coaxitron, a
wideband device with multiple tubes cascaded inside one vacuum
enclosure. These were in AWACs and some may still be supplied in the
foreign market, whereas the US planes are likely SS now. Photonis
supplies big tetrodes and triodes to Brookhaven for linac RF amplifiers
at 200 MHz.
From: David Gow<6146guy@gmail.com>
"Does Burle still exist? I can't find it on the web and supposedly NOS
Burle 8122s are for sale from India. Maxgain says they are out of stock.
I have a NCL-2000 on the shelf, the tubes are weak so I wonder if it is now
a door stop. My Henry 3KD is working well with Chinese 3-500s but the
National ishure s pretty."
Dave W7VM
Burle Industries in Lancaster, formerly the huge 1 million ft^2 RCA tube
factory, is still in business. They were bought by Photonis in France
years ago, and continue to build some tubes, for science and industry,
but very little broadcast market since they never penetrated the AM/FM
transmitter business like Eimac did in the 1980s. One of their very
special tubes is the Coaxitron, a wideband device with multiple tubes
cascaded inside one vacuum enclosure. These were in AWACs and some may
still be supplied in the foreign market, whereas the US planes are
likely SS now. Photonis supplies big tetrodes and triodes to Brookhaven
for linac RF amplifiers at 200 MHz. 73 John K5PRO
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