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Comment Metal tubes only use glass for the seals... (Score 1) 275

where the wires from the pins need to pass into the evacuated envelope. The rest of the vacuum-tight enclosure IS the metal can itself. The first metal tubes used tiny individual glass/metal eyelets for each pin, but later ones used a glass "button stem" that held all the lead-in wires in a single piece of glass.

Shortly after the metal tubes were introduced by RCA, some other manufacturers introduced the "MG" types, which were as you describe, a conventional glass tube covered with a metal can. This was done in an attempt to appear "cutting edge" with the then modern technology, but not wanting to invest in the specialized production machinery needed, and to avoid licensing the technology from RCA.

Comment Environmental regs had NOTHING to do with it (Score 1) 275

So can we skip the right-wing talking points, please? Tube manufacturing was certainly no more toxic than semiconductor fabs are (one of the most toxic industries around), and they aren't going away because of EPA regs.

US tube manufacturing died because the market for tubes went away VERY quickly once solid state devices took over in the late '60s/early '70s.

One example would be RCA, who introduced their first 100% solid state (except for the CRT) color TV sets in 1969, and closed their receiving tube plants (the largest in the US) by 1976.

With 15-20 tubes in a typical color TV set, there was a HUGE replacement market for receiving tubes and many US manufacturers each with several plants to meet the demand. Typically you would need to replace 2-3 tubes a year in a TV you used regularly. Self service tube testers (and replacement tubes) were found in drugstores and hardware stores for folks who wanted to try fixing their own sets.

Once tubes went away in new sets, the market for replacement tubes evaporated within a few years as the older tube sets hit the landfills. The relative handful of tubes still being sold were made in short runs from 1 or 2 US manufacturers who stuck it out until the '80s making a handful of types that still had some demand, but these quietly died by the early '90s, when the US military stopped supporting most of their tube-based gear and flooded the surplus market with warehouses full of unused tubes.

Tubes are still made in the US by a handful of manufacturers, but they are specialized devices used in high powered transmitters, radar, particle accelerators, and such. The ordinary receiving type tubes used in audio gear are largely made in the former Soviet bloc, which kept the remnants of their tube industry alive longer than the West did, preserving much of the manufacturing and raw materials infrastructure needed to serve the modern (much smaller) market for receiving tubes.

Comment Tubes are still made here in the US.... (Score 2) 275

But generally only the exotic special purpose and transmitting types. The commodity 12AX7s and 6L6s for guitar amps are all made offshore, due to the low profit margins. The only audio types being made in the US are Western Electric 300B triodes, which are still being made in limited numbers for the high-$$$ audiophool market.


Other remaining US tube manufacturers include CPI/Eimac:


and MU, Inc. :


, who apparently hang on making small runs of tubes to support aging military gear...

Comment SK is a CW prosign... (Score 1) 195

Although it would generally be overscored when written, and sent as one long character (...-.-) Use as a reference to a deceased operator is secondary.

  Per Wikipedia: https://en.wikipedia.org/wiki/Prosigns_for_Morse_code

The end of contact turn-over prosign is usually sent in lieu of the prosign K or the prosign at the very end of the last transmission from the transmitting station, to indicate the termination or end of a particular contact (conversation) between two stations, thus turning the communications channel over to other users. The prosign may be interpreted in English as, this station will be "silencing key". Often when terminating a contact with the prosign, a transmitting station may continue listening on the communications channel for calls from other stations.

Comment Likely to be fundamental overload, actually.... (Score 1) 195

For better or worse, most ham operators these days use commercially made equipment, which is tested for spectral purity, so any significant output on broadcast or cellular bands is highly unlikely.

What often causes amateur band RFI/TVI nowadays is lack of filtering/shielding in cheap consumer electronics, to allow them to reject signals outside of their operating bands. Such "frills" are among the first design features eliminated in order to lower the selling price at WalMart.

If the ham operator is putting out a clean signal, within legal power limits, then this type of interference is strictly the problem of the person being interfered with. Most hams are more than willing to lend a hand resolving the problem just to be a good neighbor, but they have NO legal responsibility to go off the air or repair design deficiencies in your TV, router, or whatever. And the FCC will simply point out the Part 15 regs that lay this all out. Your consumer electronics cannot interfere with any licensed service (like ham radio), and must accept any interference FROM a licensed service.

Comment Jamming is already illegal under federal laws.... (Score 1) 195

and the biggest "attack vector" against cell phones would be the "stingray" being deployed by your local police department.

But sure, we have to crack down on ham radio so you can feel safe. Because somebody who wants to secretly jam communications is going to put up a big, obvious antenna installation in order to do so.

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