Do you recall when the FAA, finally, went all solid state?
On 4/5/26 14:15, John Lyles wrote:
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.
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