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"pfjw@aol.com" <peterwieck33@gmail.com>: Apr 25 09:45AM -0700 > >"Nuke magnetrons use thoriated tungsten bright emitters. "   > AHA, so that filament is already burning pretty hot then right ? I see.   No, they don't. The emitter is a solid cylinder of Barium Oxide with a (usually) copper filament inside it. There are other Barium salts used as well, but no Thorium.   "Bright Emitter" magnetrons are used mostly for industrial heating applications - not hardly in what you have in your kitchen - even an old Amana, or Litton. The cutting-edge of magnetrons is in making more compact and shorter-wave (high-resolution) radars. Neat stuff going on there.   Peter Wieck Melrose Park, PA

tabbypurr@gmail.com: Apr 25 11:05AM -0700 On Wednesday, 25 April 2018 17:21:29 UTC+1, jurb...@gmail.com wrote: NT   > >"Picking the first random ES design I see 475v dc bias. "   > According to RCA's RC30 the peak pulse plate voltage it rated 5,000 volts. Without reading all the details this is of course with negative voltage on G1, it is the retrace pulse for the yoke and rectified for HV. So a pair stacked SESAPP would yield 2,000 volts peak at best. Bridged, of course 5,000 volts. I'm fairly sure most ESLs need more than that. Without going to transmitter tubes I think that is about the highest voltage to be had except in a HV shub regulator such as a 6BK4. Those are good for 27,000 volts but at 5,000 volts will only pass 750 uA. I think that only works out to about 16 watts. Unless ESLs lose a ton of power in the internal transformer that will not do. The book doesn't give plate dissipation but the tube s designed with the anode away from the glass and they do get red hot and work just fine. It is not impossible though, first of all with that topology, triodes should be easier to deal with. It would be a matter of a bunch of them in parallel which would cost more, but a true audiophile doesn't care.   you already know that some ESes run at under 1kV, and the once mildly popular ES tweeters ran direct off ordinary audio amp valve anodes. But you can build a megavolter if you want.       > In light of that, when I replace the cap in this 1992 Litton, what about using a higher value to squeeze a few more watts out of it ? Is that too dangerous or otherwise not feasible ? To me, it is damn hard to have too much power, you just use less time, and since this doesn't ave real power control as far as I know, it just cycles anyway. Of course it might already have the biggest value on practice because it is a fairly large unit and I remember it had alot of power when it was new. We had to get used to it, it wasn't like the elcheapos. I would up the cp value for decent results but if it is going to burn something up because of it I'll leave it as designed.   > >"Nuke magnetrons use thoriated tungsten bright emitters. "   > AHA, so that filament is already burning pretty hot then right ? I see.   Nuke magnetrons run red hot. I wouldn't want to heat them even further. I used to have a nuke that had its magnetron on show, no cover at all between it & the cooking cavity.   The HV cap doesn't affect filament power of course.     NT

Chuck <ch@dejanews.net>: Apr 25 04:17PM -0500 On Wed, 25 Apr 2018 06:40:06 -0700 (PDT), "pfjw@aol.com"   >Does not seem to be much Thorium involved??   >> Peter Wieck >> Melrose Park, PA The filaments in the finals in WWII tank transmitters ran white hot. Had an early 20s Crosley radio which didn't have cathodes and the filaments glowed orange. (RCA WD11s)

Chuck <ch@dejanews.net>: Apr 25 04:22PM -0500 >I had some ideas for electrostatic speakers, could have worked but I found out it had been tried. I guess it wasn't worth the trouble sonically. I was going to take some 6MJ6sw or other horizontal output tubes and run them stacked and bridged to eliminate all the transformers, making it DC coupled. I think I would have had to run them stacked in series (like an Ampzilla) to get the required voltage. not a cheap undertaking but neither are ESLs in the first place.   >Ever see the schematic for the ESL-63s ? Thing has a delay line with several taps. It is said that the sound is like it is coming from behind the speaker, that's probably why.   >Some say those Maggies lack bass. I found them not to be "heavy" by any stretch, bit not really lacking. For my use I would have used subwoofers with them, but I am a bass freak.   Used to work on Quad ESL-63s. They sounded great but couldn't be played at high levels. When they arced from being over driven or moisture incursion the damage could be pretty extensive.

bruce2bowser@gmail.com: Apr 25 08:12PM -0700 On Wednesday, April 11, 2018 at 4:14:03 AM UTC-4, GS wrote: > > Stretch over the active face of each cart with a drop of > > meths/denatured-alcahol in each balloon and store on a ledge with balloons dangling.   > My Canon I hardly use. It just uses ink even while off.   There. Now. Footing the bill of some nameless, faceless corporation wasn't that bad after all, was it?

"pfjw@aol.com" <peterwieck33@gmail.com>: Apr 26 05:41AM -0700 On Wednesday, April 25, 2018 at 5:17:33 PM UTC-4, Chuck wrote:   > The filaments in the finals in WWII tank transmitters ran white hot. > Had an early 20s Crosley radio which didn't have cathodes and the > filaments glowed orange. (RCA WD11s)   Transmitter tubes do tend to run hot. Similar to larger mercury rectifier tubes. In some cases, those had to be shielded (enclosed) due to UV emissions. Back in the day, I ran a 35mm projection set-up that used carbon-arc lights. They were driven by mercury rectifier tubes about 10" tall and in metal enclosures against the UV.   But standard receiving tubes, not so much. And modern microwave oven magnetrons, not at all.   Peter Wieck Melrose Park, PA

Ralph Mowery <rmowery28146@earthlink.net>: Apr 26 11:18AM -0400 In article <56cad77f-1bbd-48e9-8259-4e86dca8fc76@googlegroups.com>, peterwieck33@gmail.com says...   > But standard receiving tubes, not so much. And modern microwave oven magnetrons, not at all.   > Peter Wieck > Melrose Park, PA   As most transmitting tubes are only about 75% or less efficent, they will run hot. A 1000 watt input tube will send out maybe 750 watts best case, usually less, that is 250 watts or more heating the tube not counting the filiment power.   If you do not think a receiving tube is hot, grab a power output tube of an old All American 5 AM receiver, or for that mater, a 6aq5 or similar in other receivers audio output stages with your fingers.

Fox's Mercantile <jdangus@att.net>: Apr 25 11:41PM -0500 And because I have way too much free time, I'm configuring five Cisco 7940G two-line phones.       -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

"Gareth Magennis" <soundserviceleeds@outlook.com>: Apr 25 07:21PM +0100 Found 2 12AT7 valves inside a Fender (Evil) Twin today.   Both branded 12AT7, National, made in USA.   Except one is way bigger than the other one.   http://i67.tinypic.com/fc0ehi.jpg       The bigger one has a plate structure some 1.75 times taller than that of the smaller one, yet both are apparently 12AT7.     On my valve tester, the larger valve traces showed approximately twice the current of the smaller one. The curves basically look like this is a double current 12AT7.       What is it?         Gareth.

"pfjw@aol.com" <peterwieck33@gmail.com>: Apr 25 11:34AM -0700 On Wednesday, April 25, 2018 at 2:21:55 PM UTC-4, Gareth Magennis wrote:   > What is it?   > Gareth.   It is a 'mistake' - pure and simple, nothing exotic at all.   "National" as distinct from National Union (NU, later, Philco) was a rebrander of tubes, and once upon a time, the house brand for a number of retail tube sellers including Richardson Electronics. Much of their stock came from surplus, pulls and culls from the actual manufacturers and in point of-fact sold with no further testing than fitting in the appropriate box after relabeling.   What you have is a tube getting mixed into a lot, scrubbed, painted and boxed, and sent off into the world with no further thought.   Peter Wieck Melrose Park, PA

Phil Allison <pallison49@gmail.com>: Apr 25 08:16PM -0700 Gareth Magennis wrote:   > The bigger one has a plate structure some 1.75 times taller than that of the > smaller one, yet both are apparently 12AT7.   ** https://en.wikipedia.org/wiki/12AT7   Nothing to worry about, the shape and size of plate structures of common twin triodes vary a lot.       .... Phil

"~misfit~" <shaun.at.pukekohe@gmail.com>: Apr 26 01:22PM +1200 Once upon a time on usenet Mike S wrote: > http://www.bbc.com/news/science-environment-29465446   > The Hidden Earth: Undersea Mountains by the Thousands > http://www.slate.com/blogs/bad_astronomy/2014/10/07/geography_thousands_of_undersea_mountains_discovered_via_satellite.html   Interesting, thanks. -- Shaun.   "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM*." David Melville (in r.a.s.f1) (*Diagnostic and Statistical Manual of Mental Disorders)

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