Richard Knoppow a écrit :
Hi !
----- Original Message ----- From: "Ryuji Suzuki" <rs@xxxxxxxxxxxxxxx> To: <pure-silver@xxxxxxxxxxxxx> Sent: Thursday, April 06, 2006 12:52 PM Subject: [pure-silver] Re: Deionized Water-Advantages & Sources?
The tube in the stand at the top is typical of the water cooled tubes I was refering to.On Thu, 6 Apr 2006 11:36:53 -0700, "Richard Knoppow" <dickburk@xxxxxxxxxxxxx> said:
Anodes were never made of carbon but were probably surface treated. The anode material had to be mechanically strong enough to contain the very high vacuum in the tubes. The anode was in the form of a long cylinder with a rounded end. The top of the tube was glass with the other contacts in it. One of the big tricks in making tubes was learing how to make good glass to metal seals. The water cooled tubes also had air cooling for the top to keep the seals cool. The tubes sat in ceramic tubs which contained the cooling water. Circulation was through ceramic pipes. Since these transmitters were not very efficient the heat dissipation was probably on the order of the transmitter power or more.
This is not RCA so they may look very different, but you can see some of the water-cooled final stage tubes here:
http://kagakukan.toshiba.co.jp/history/1goki/1919radio/index.html
The tube with the fins in the bottom picture looks just like the RCA air cooled ones. The first air cooled tubes were just water cooled ones with the fins soldered to the anode. They also sat in ceramic pot type sockets with the air conduced up through the fins.
Here's a Simens:
http://www.radiocraft.co.jp/rc_tube1.html
Econco is a major rebuilder of tubes, I used to see one of their people when I was active with the local chapter of the Socity of Broadcast Engineers. This appears to be a water cooled UHF tube designed to fit a coaxial resonator.
The tubes used in broadcast transmitters up through the 1960s were mostly simple triodes and could be rebuilt.
Also, the toshiba page describes that they had 20kW short wave final tube with water-cooled *cathode* around 1950.
I personally have no experience with anything like these. The biggest tube I've ever used is 6146B driven by 12BY7A. My main interest was in UHF and SHF so these guys are too big.
Also, water has pretty significant dielectric constant with big dielectric loss, so I wouldn't use water in direct contact with any of the circuits I was building...
In terms of corrosion resistance, high chromium stainless steel and titanium are pretty good. I've been looking for a reaction vessel that is made from poor electric conductor but excellent heat conductor. Does anyone know such a material? (Besides beryllium oxide, of course.)
Water cooled tubes were made even for UHF television but I am not sure the water came in direct contact with the anodes. The older tubes were used for medium wave and short wave transmitters.
I have a catalogue of Western Electric transmitter tubes c.1936 which I will have to dig out. The 100KW tubes they used in their 50KW broadcast transmitters stood as high as a man. The transmitter installations had portable cranes for moving them.
Modern transmitters are very small, a 5KW AM transmitter being the size of a large refrigerator. Like so many other things in modern life, all the romance has been removed from this stuff.
When I was an active ham I could not afford high power stuff so I also worked mostly with limited power. My microwave experience began at Hewlett-Packard many years ago where I was a microwave insrument specialist. I worked on everything but would up doing field service on computerized spectrum analysers and circuit analysers.
--- Richard Knoppow Los Angeles, CA, USA dickburk@xxxxxxxxxxxxx
