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RE: Eimac 3-1000H Tube Info - TNX
About the rattling tube thing...
There are types of glass that soak up and
trap water vapor. I don't know if they still do but
they used to put a slab of this stuff in the metal cap
of diamond mount power transistors (TO5 can?) to
scavange the last bit of stray water vapor in the
envelope.
I've seen glass chips in vacuum tube
envelopes. I'd bet it's there for the same reason.
the vacuum in a tube isn't perfect but it better be
dry.
So just because a tube rattles doesn't mean
it's dead. They aren't as simple as lightbulbs.
Just a thought...
John
>Original Poster: "Dale, Martin" <martin.dale-at-ntu.ac.uk>
>
>
>
>> ----------
>> From: Tesla List[SMTP:tesla-at-pupman-dot-com]
>> Sent: Thursday, May 20, 1999 12:44PM
>> To: tesla-at-pupman-dot-com
>> Subject: Eimac 3-1000H Tube Info - TNX
>>
>> Original Poster: TeslaTec-at-webtv-dot-net (Tony R Greer)
>>
>> Hello to David T, Martin D, David S, Ralph Z, and coilers all .....
> snip>>
>> Speaking of big tubes, I also have a water-cooled Eimac 4W-20,000A, a PA
>> tube from a local TV station xmitter. Too bad something inside rattles,
>> so its probably no good :-(
> snip>>
>
>Tony, I've found that tubes that rattle aren't always dead tubes!
>
>One of my 4CX1000A's rattles like er... a rattle, and it works like new!
>and I've got lots of 4CX250B's that tinkle and rattle and are ok, so it
>might just still be ok.
>Bit of a brute to power up though!
>I bet the heaters going to need getting on for 100A!
>
>Incidentally, The great thing about Eimac tubes, is that you can learn a lot
>about what sort of tube it is just from the type number.
>i.e; the first character is the electrodes (3 = triode, 4 = tetrode, 5 =
>pentode...)
>the 2nd character is the type of insulation or envelope (C = ceramic, a dash
>(-) or space = glass insulation or envelope)
>the 3rd character is usually the type of cooling (X = forced air, W = water,
>V = vapour, R = radiation...)
>
>This is usually followed by the anode (plate) dissipation in watts.
>Only the last letter has lots of different meanings, usually relating to the
>tubes gain, cathode type etc
>
>Some tubes have the letter P after the insulation type, (such as the
>3CPX800) signifying that the tube is designed for pulse service.
>
>These should be ideal for Tesla coil service too!
>
> Martin Dale, G6ABU Nottingham England