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In Reply to: RE: 83 MV rectifier: overcoming the fear... posted by deathtube 667 on December 24, 2011 at 14:07:48
if you use Type 83s inside your home, your forum moniker is PERFECT
deathtube.
Not the tube,.........but unfortunately, you.
Where do you think the mercury goes, as the tube ages and it all "drys out". Its inside many a vintage movie theatre projection booth.
Cool looking blue glow, yep. Sounds real low Z and better, usually yep.
IMHO, get rectification done "a different way" is my advice, for example, use dual 5U4s or dual 5V3s. Much safer for you, your kids, and your wife.
Jeff Medwin
Follow Ups:
If a mercure rectifier is shaken, the mercury tends to distribute itself over the glass surface of the tube, so it may appear to have evaporated, because one can no longer discern any liquid in the bottom of the tube, but I don't think evaporation through the glass envelope is a common phenomenon. OTOH, nothing made by man is perfect.
If pressure is on the outside of such magnatude as a vacuum of at least 10-4 Torr inside, I doubt the mercury at the molecule level could escape to the outside. A photon does escape though.
As you may or may not know, this claim of mercury migration by Jeff is eons old but pops up out of nowhere on occasion. Jeff comes by this info from his bud Dennis of "Serious Stereo" notoriety. As the story goes, Dennis apparently serviced old style movie projection equipment in one of his numerous careers. Dennis explains that in the projection booths, mercury rectifiers were used for some purpose (unknown to us). Dennis found evidence of vast quantities of free mercury in these booths and so concludes that the mercury was able to migrate out of the glass envelope during operation and collect in the booths.
For reasons already stated, I believe it is extremely unlikely that mercury is able to migrate out of a properly sealed envelope under any condition. Simple breakage occurring many times over the years is the more likely explanation of mercury in the projection booth if any was truly detected there at all. This possibility goes unstated by Dennis or Jeff.
Before Xenon lamps took over in the 1960s they used carbon arc lamps in the projector. They ran on DC and were anywhere from 2kw to 10kw in some extreme cases - like Radio City Music Hall.Motor generators were most popular but Mercury Vapor rectifiers were also used as they were more efficient. And at 2-10kw, they were quite large, like a 64oz soda bottle. Early sound systems probably used the popular audio size mercury rectifiers in their amps as well.
Radio and TV transmitters also used Mercury rectifiers into the 1970s.
Edits: 12/26/11 12/26/11 12/26/11 12/26/11
Slightly off topic, but some may find this interesting.
"Radio and TV transmitters also used Mercury rectifiers into the 1970s."
These are still in operation. It's at KMPC, a 50kW AM station.
WOW! that a whole bunch of 857B Rectifiers.
I have a couple of them and also have an American Filament Transformer as well. Looks like they could be useing the same iron as well.
than I would (now) using the Keith Monks mercury contact tonearm I used to own.
For the uninitiated, the Monks had a base with four wells in which mercury was added, via an eyedropper. The unipivot arm had four pins below the pillar, which were lowered into the individual wells. The theory was the elimination of wire drag as the arm traversed the record.
It did sound good, but I always wish I'd purchased the albeit slightly poorer sounding, but safer and saner SME. The frequent loss of channels due to the oxidation of the mercury, occasionally spilled drops from the eyedropper, and the toxic nature of the beast were simply not worth it.
I would have to agree that I can't see how an unbroken rectifier tube would be creating pools of mercury in a projection booth, or your listening room.
nt
Jeff, how does mercury excape a glass tube when a vacuum exists inside?
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