The AM Forum

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It looks like the "evac" part of the tube was left on... to what purpose?? I don't know...   klc

I would avoid them. Normally, ALL tubes have a port like that sticking out of the bottom (or top) in the vacuum forming process that makes the glass envelope. The machine then sucks the tube down thru there, and heats it up close to the tube. A quick twist while the suction port is red, and the tube is sealed with a 1/2" long tip-off.

I've heard of these 833's floating around. I guess they were supposed to be tubes that didn't pass QC for one reason or another and were pulled off the machine before evacuation, but I've never seen one. (common QC fail would be the pins not being straight) That might explain the funny coloring on the anode. Maybe someone tried to fire it up.

One way or another, unless your getting them for free, I would keep looking.

Well there is a guy on eBay selling them NOS now. Do a search. I asked him about that. It seems the long stem was for filament & plate sediments. In the last days of AM tube radio transmitters and before solid state BC transmitters came on the market, there was premature failing of Amperex 833A tubes when subjected to Hip Hop and Rap music. They beefed up the internal workings of the tube but found without the long stem the diffused plate material would fill up the bottom of the envelope and eventually short out the grid leading to a thunderous implosion. This sound was recorded by a specially developed vacuum microphone installed in the glass of a test Amperex 833A. Amperex only made 5000 of these specialty tubes. They discontinued when it was found that large bass notes on Hip Hop, would shake the tube violently in the socket and brake off the stem.

Stemming from that experience, the Long Stem Amperex 833A is no more.

Terry,
I cant stop laughing.........jeeezz.

thats a load of crap. more likely those tubes have nothing but air in them because he got a hold of a bunch of unfinished rejects out of a dumpster that failed some QC test prior to evacuation of the tube. No vacuum in those babies, I bet.

But if that's the case, why is the end of the stem closed off?

What's a load of crap?  I also thought that perhaps they weren't sucked down but the guy selling the on eBay has them in sealed boxes.

Rather strange how serious some of you guys are.

I gotta jump here.....Terrys post was a JOKE......that was obvious....but it seems that some people took it seriously. No one is trying to argue with anybody I hope.
Sometimes this board gets a little tedious. Lets not take ourselves so freeken seriously.
Have a nice weekend.
Bill

"long stemmed 833a's" I can't stand it.

It's especially funny when sarcasm misses some people and not others.

Thank's for the laugh.

I think those are male 833s

One of those tubes would make a good slime-o-tron!

http://amfone.net/Amforum/index.php?action=dlattach;topic=9464.0;attach=1602;image

The one minor problem with conversing in text is one may not pick up on sarcasm or wiseguy remarks especially if emoticons aren't used unlike conversing verbally or face to face where voice inflections and facial expressions can easily discern horsing and kidding around.

I apologize for my post poking fun at an Amperex 833A. That’s all it was. There was no need for this to go in another direction. I was hoping that someone would come up with something funny about the engineering of that tube. I did my best. I guess it failed.

Maybe they havent been circumsized yet!

Actually Frank, you are very close.

These are clearly very young tubes, not yet fixed for servicing transmitters.

For those with farm backgrounds, you may have heard of "wether sheep," and these are pre-wether.

Once you complete the "process," as with a young sheep, you have quite the serviceable tube.