POISON.
Hi,
It does, as I said earlier it may take a lenghty translation exercise on my part but rest assured it's not healthy for the tubes.
Granted, the study is based on MTBF studies done on CRTs but it applies to any tube really.
The documents were publishished by the Dutch (defunct?) mag Audio & Techniek and covered AC versus DC heating etc.
The invitee was an ex Philips engineer, the redaction plus some audionuts such as Audio Note importer Ed de Jong, some other people I can't quite remember and yours truly.
This poisoning is one reason why I so often object on totally unnecessary stand-by arrangements such as leaving 1/2 B+ on the anodes or reducing heater voltages by half and so on.
One can actually create new types of tubes by "forming" them on particular voltages for a while, it seems tubes have some kind of memory as most other parts but I'm pushing...
If you like I can dig up that document and mail it to you, it's slightly over 1 Megabyte in size and in PDF format thanks to fellow member Remco (AKA Analogue something...).
Cheers,
Hi,
It does, as I said earlier it may take a lenghty translation exercise on my part but rest assured it's not healthy for the tubes.
Granted, the study is based on MTBF studies done on CRTs but it applies to any tube really.
The documents were publishished by the Dutch (defunct?) mag Audio & Techniek and covered AC versus DC heating etc.
The invitee was an ex Philips engineer, the redaction plus some audionuts such as Audio Note importer Ed de Jong, some other people I can't quite remember and yours truly.
This poisoning is one reason why I so often object on totally unnecessary stand-by arrangements such as leaving 1/2 B+ on the anodes or reducing heater voltages by half and so on.
One can actually create new types of tubes by "forming" them on particular voltages for a while, it seems tubes have some kind of memory as most other parts but I'm pushing...
If you like I can dig up that document and mail it to you, it's slightly over 1 Megabyte in size and in PDF format thanks to fellow member Remco (AKA Analogue something...).
Cheers,
STANDING OVATION.
Hi,
Absolutely...wish we had more members like this.
Quite refreshing after a long series of the kind look Ma what I found in the junk box...anything I can do with it ?
How do I tack this odd-ball to that one, etc and manage to drive half the forum nuts with impossible questions.
Sorry to sound harsh,
Hi,
Absolutely...wish we had more members like this.
Quite refreshing after a long series of the kind look Ma what I found in the junk box...anything I can do with it ?
How do I tack this odd-ball to that one, etc and manage to drive half the forum nuts with impossible questions.
Sorry to sound harsh,
Re: POISON.
Yes, please.
Just to add confusion, studio tube cameras always ran their tubes in standby to extend their life. (63% heater voltage, then full heater voltage, then HT after one minute delay.) Each of our four cameras used four tubes, and at £1,500 a pop, you really wanted to get every hour you could out of them. They typically lasted 3,000 hours, although we had a couple that were 17,000 hours old, and still producing nice pictures.
fdegrove said:
Yes, please.
Just to add confusion, studio tube cameras always ran their tubes in standby to extend their life. (63% heater voltage, then full heater voltage, then HT after one minute delay.) Each of our four cameras used four tubes, and at £1,500 a pop, you really wanted to get every hour you could out of them. They typically lasted 3,000 hours, although we had a couple that were 17,000 hours old, and still producing nice pictures.
Mr. Microwave speaks.....
In the world of microwave TWTs, heater voltage is very tightly controlled for maximum tube life and performance. Too high, and yep, it dies too fast. Too cold, the tube gets "gassy", and emission goes down.....which leads to high helix current, and......etc....
In brief, it kills tubes also. I would assume that much the same applies to conventional small signal tubes. Although I suspect lower heater voltage.......within reason......... would not have as great a negative effect.
Jocko
In the world of microwave TWTs, heater voltage is very tightly controlled for maximum tube life and performance. Too high, and yep, it dies too fast. Too cold, the tube gets "gassy", and emission goes down.....which leads to high helix current, and......etc....
In brief, it kills tubes also. I would assume that much the same applies to conventional small signal tubes. Although I suspect lower heater voltage.......within reason......... would not have as great a negative effect.
Jocko
Guys, You are the best!
I never thought that my little question would get ANY answer. (I'm rather new to computers/internet and this kind of forum)
Richardson/Dushmann ???? Did a search here and found nothing.
And I'm not afraid to ask.
I'm old enough to know my eletronics about electrones, holes, etc (been a electrician for over 30 years) But when it comes to tubes, they were all vapourized when I attended high-school.
"I'm not old, it's just that I have lived longer the the rest of you"
thanks again
björn
I never thought that my little question would get ANY answer. (I'm rather new to computers/internet and this kind of forum)
Richardson/Dushmann ???? Did a search here and found nothing.
And I'm not afraid to ask.
I'm old enough to know my eletronics about electrones, holes, etc (been a electrician for over 30 years) But when it comes to tubes, they were all vapourized when I attended high-school.
"I'm not old, it's just that I have lived longer the the rest of you"
thanks again
björn
TWTs
Yes, they had a "getter". Most were made by EEV, I assume you may know who they are. Later, Varian and Siemens got into the act.
As for life expectancy vs. anode voltage; yes, lowering it did greatly extend life. But it was necessary to get maximum power out at all times. Otherwise, no one would have made any long-distance phone calls up until the late 80s when single-mode fiber became common.
Jocko
Yes, they had a "getter". Most were made by EEV, I assume you may know who they are. Later, Varian and Siemens got into the act.
As for life expectancy vs. anode voltage; yes, lowering it did greatly extend life. But it was necessary to get maximum power out at all times. Otherwise, no one would have made any long-distance phone calls up until the late 80s when single-mode fiber became common.
Jocko
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