12AX7 failure

"Peter Wieck" <pfjw@aol.com> wrote in message
news:b5e82fdf-e9c2-4064-a26a-6c054174e50f@e12g2000yqm.googlegroups.com...
On Nov 22, 11:36 am, "N_Cook" <dive...@tcp.co.uk> wrote:
What would cause the failure of one half of a 4 year old 12AX7 ? A very
careful owner.
Click to expand...
For some reason, whenever a thread starts with "12AX7", "EL84", or "6L6", I
feel like I'm viewing the famous "Three Stooges" skit, "Niagara Falls",
after I read all the replies!

Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!

Omer
 
Omer S wrote:

Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!
Click to expand...
Its not *four years*, but only the ON-time in four years.

You living on some island where tubes grow on trees?

Regards,
H.
 
On Nov 27, 6:43 am, Heinz Schmitz <HeinzSchm...@gmx.net> wrote:
Omer S wrote:
Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!

Its not *four years*, but only the ON-time in four years.

You living on some island where tubes grow on trees?

Regards,
H.
Click to expand...
Yikes!!

a) If the tube was Chinese, 6 weeks of "on-time" would be a lot in
some cases.
b) Current-production tubes are readily available. Not for free, and
one may vastly over-pay, but it is not as if it were a 19T8 or some-
such.
c) After determining that the equipment itself was not at fault, then
yes s&*t-can the tube and move on.

Peter Wieck
Melrose Park, PA
 
Heinz Schmitz wrote:
Omer S wrote:

Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!

Its not *four years*, but only the ON-time in four years.
Click to expand...

So? Most tubes were only 90 day or one year warranty when they were
in full production. It wasn't uncommon to replace a failed tube, under
warranty. There are a lot of things that are involved in MTBF.


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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
 
"Heinz Schmitz" <HeinzSchmitz@gmx.net> wrote in message
news:dp1ti4tq28jp1dp6jfs68auo321pbacoda@4ax.com...
Omer S wrote:

Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!

Its not *four years*, but only the ON-time in four years.

You living on some island where tubes grow on trees?

Regards,
H.
Click to expand...
An interesting link, for further analysis of what could bring the demise of
12AX7 vacuum tubes,

Http://www.vaccuumtubefans.org/forums/Topic_12AX7
 
Omer S <oabukovac@earthlink.net> wrote in message
news:2qydnWXJurmbtbLUnZ2dnUVZ_r_inZ2d@earthlink.com...
"Heinz Schmitz" <HeinzSchmitz@gmx.net> wrote in message
news:dp1ti4tq28jp1dp6jfs68auo321pbacoda@4ax.com...
Omer S wrote:

Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!

Its not *four years*, but only the ON-time in four years.

You living on some island where tubes grow on trees?

Regards,
H.


An interesting link, for further analysis of what could bring the demise
of
12AX7 vacuum tubes,

Http://www.vaccuumtubefans.org/forums/Topic_12AX7
Click to expand...

Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7

googling 1 c or cc or subdirectories, or similar domain got nowhere,
unusually. Nothing found via kloth.net domain whois


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
Michael A. Terrell wrote:

There are a lot of things that are involved in MTBF.
Click to expand...
Yes, indeed.
But I guess that we are interested in those which we can influence.
Like e.g. (?)
- heating before applying anode voltage,
- avoiding long periods without anode current,
- ??

Regards,
H.
 
pfjw@aol.com wrote:

b) Current-production tubes are readily available. Not for free, and
one may vastly over-pay, but it is not as if it were a 19T8 or some-
such.
Click to expand...
I hear that presently there are only russian and chinese productions
going on. Hard to get at - if you'd agree that an eBay-buy from
Ukraina or China is somewhat "hard" :).

I think that most of the post-war radio tubes are available only as
NOS (ECH81, EF4x, EF8x,ELxx ...). Somebody should make some
fivehundred EM34/35 and earn himself a good meal.

Generally I found that to buy tubes is a lottery except if you have a
known and trustworthy dealer. Many deaf nuts being handed around.

Regards,
H.
 
Heinz Schmitz wrote:
Michael A. Terrell wrote:

There are a lot of things that are involved in MTBF.

Yes, indeed.
But I guess that we are interested in those which we can influence.
Like e.g. (?)
- heating before applying anode voltage,
- avoiding long periods without anode current,
Click to expand...

Useless on low power vacuum tubes that are not used in some bizarre
circuit. Its a different matter on high power transmitter tubes.

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http://improve-usenet.org/index.html

aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.

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your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ggogs2$vn$1@news.motzarella.org...
Omer S <oabukovac@earthlink.net> wrote in message
news:2qydnWXJurmbtbLUnZ2dnUVZ_r_inZ2d@earthlink.com...



Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7
Click to expand...
How about this link?

Http://www.vaccuumtubefans.org/forums/Topic_12AX7
 
Omer S wrote:
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ggogs2$vn$1@news.motzarella.org...
Omer S <oabukovac@earthlink.net> wrote in message
news:2qydnWXJurmbtbLUnZ2dnUVZ_r_inZ2d@earthlink.com...



Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7


How about this link?

Http://www.vaccuumtubefans.org/forums/Topic_12AX7
Click to expand...
Oh, Omer (Polly). What are we to think of you? Sigh.

-ex
 
Omer S wrote:

Http://www.vaccuumtubefans.org/forums/Topic_12AX7
Click to expand...
nope, and networksolutions.com says that doesn't exist as a domain either.

Jeff
 
N_Cook wrote:
Omer S <oabukovac@earthlink.net> wrote in message
news:2qydnWXJurmbtbLUnZ2dnUVZ_r_inZ2d@earthlink.com...
"Heinz Schmitz" <HeinzSchmitz@gmx.net> wrote in message
news:dp1ti4tq28jp1dp6jfs68auo321pbacoda@4ax.com...
Omer S wrote:

Why is it so important to debunk a failing tube that gave four years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!
Its not *four years*, but only the ON-time in four years.

You living on some island where tubes grow on trees?

Regards,
H.

An interesting link, for further analysis of what could bring the demise
of
12AX7 vacuum tubes,

Http://www.vaccuumtubefans.org/forums/Topic_12AX7






Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7
Click to expand...
Same problem here.

I googled vaccuumtubefans and all I got was pointers back to this thread.
 
nobody > wrote:
N_Cook wrote:
Omer S <oabukovac@earthlink.net> wrote in message
news:2qydnWXJurmbtbLUnZ2dnUVZ_r_inZ2d@earthlink.com...
"Heinz Schmitz" <HeinzSchmitz@gmx.net> wrote in message
news:dp1ti4tq28jp1dp6jfs68auo321pbacoda@4ax.com...
Omer S wrote:

Why is it so important to debunk a failing tube that gave four
years of
satisfactory performance?

Dude, just $#!^can the offending tube, and move on!
Its not *four years*, but only the ON-time in four years.

You living on some island where tubes grow on trees?

Regards,
H.

An interesting link, for further analysis of what could bring the demise
of
12AX7 vacuum tubes,

Http://www.vaccuumtubefans.org/forums/Topic_12AX7






Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7


Same problem here.

I googled vaccuumtubefans and all I got was pointers back to this thread.
Click to expand...
The fellow who parroted and corrected another guy's link has a
reputation for not having verified his sources of info. Nuff said.
 
exray wrote:
The fellow who parroted and corrected another guy's link has a
reputation for not having verified his sources of info. Nuff said.
Click to expand...
Back up and check the attributes Bill, The only one Omer is parroting
is himself.

Jeff
 
Michael A. Terrell wrote:

There are a lot of things that are involved in MTBF.

Yes, indeed.
But I guess that we are interested in those which we can influence.
Like e.g. (?)
- heating before applying anode voltage,
- avoiding long periods without anode current,

Useless on low power vacuum tubes that are not used in some bizarre
circuit. Its a different matter on high power transmitter tubes.
Click to expand...
Your kind posting shares a property with many usenet postings:
It provokes the most valuable question: "Why?".

Regards,
H.
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ggogs2$vn$1@news.motzarella.org...
Omer S <oabukovac@earthlink.net> wrote in message


Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7

googling 1 c or cc or subdirectories, or similar domain got nowhere,
unusually. Nothing found via kloth.net domain whois
Click to expand...
Try this one!

http://tinyurl.com/4xur8r

Omer
 
Heinz Schmitz wrote:
Michael A. Terrell wrote:

There are a lot of things that are involved in MTBF.

Yes, indeed.
But I guess that we are interested in those which we can influence.
Like e.g. (?)
- heating before applying anode voltage,
- avoiding long periods without anode current,

Useless on low power vacuum tubes that are not used in some bizarre
circuit. Its a different matter on high power transmitter tubes.

Your kind posting shares a property with many usenet postings:
It provokes the most valuable question: "Why?".
Click to expand...

Why, what? Have you ever seen any provable problems with low power
receiving tubes, or ar you just another tube freak repeating fairy tales
and folklore? Do you have decades of real experience with all types of
vacuum tubes behind you, or are you YAKIAH?


--
http://improve-usenet.org/index.html

aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
 
In article <r682j4hof3pdn1bcvhf0nimm63avssmqv8@4ax.com>,
Heinz Schmitz <HeinzSchmitz@gmx.net> wrote:

Michael A. Terrell wrote:

There are a lot of things that are involved in MTBF.

Yes, indeed.
But I guess that we are interested in those which we can influence.
Like e.g. (?)
- heating before applying anode voltage,
- avoiding long periods without anode current,

Useless on low power vacuum tubes that are not used in some bizarre
circuit. Its a different matter on high power transmitter tubes.

Your kind posting shares a property with many usenet postings:
It provokes the most valuable question: "Why?".
Click to expand...
So the real question is, is there anyone out there that can give a comprehensive
answer as to why?

Even the belief stated above that "Its a different matter on high power
transmitter tubes" with respect to "heating before applying anode voltage"
appears questionable.

Some 45 years ago I worked at several different stations as a broadcast engineer
and the old-timers there trained us young kids to be sure we thoroughly warmed
up the filaments before applying the plate power. The precise reasons for doing
this were never made completely clear. With the notable exception of one newly
installed RCA BTF-10D,the vast majority of the transmitters I worked with used
mercury vapor rectifiers, one even used two stacked banks of mercury vapor
rectifiers to provide the 17 kV B+ voltage. Obviously in transmitters using
mercury vapor rectifiers it is necessary to warm the rectifier filaments up
before applying power to the plate transformer(s), since dire things would
transpire if the mercury wasn't properly vaporized before the rectifiers where
hit with power from the plate transformer(s). But ignoring the mercury vapor
rectifiers was it really necessary to warm up the power tubes before applying
plate power? I was surprised a few years back to read in the instruction manual
for a tube transmitter the statement that it was not necessary to warm up the
power tube filaments before applying plate voltage! And they weren't just
saying that the automatic sequencer would take care of the correct sequencing of
the filament and plate power, the statement made clear that they were talking
about actually applying filament and plate power to the tube simultaneously. I
found this surprising since I had been trained to warm up the power tubes before
applying the plate voltage, and there are other reasons for warm up, so I asked
about this on a forum or newsgroup, the exact one has escaped me. A current
broadcast engineer replied and said yes that was true, it was generally not
necessary to warm up most power tube filaments before applying the plate
voltage. He did go on to explain that this was not universally the case however
and said there were certain types of tubes that did need to be warmed up first,
but I have forgotten what the reason was that he gave, probably something about
filament construction or material.

So does anyone have a comprehensive explanation of this cathode warm up issue,
for both low power and high power tubes?

--
Regards,

John Byrns

Surf my web pages at, http://fmamradios.com/
 
Very funny ;o) At least I know how the taskman works! - JP


"Omer S" <oabukovac@earthlink.net> wrote in message
news:lZ6dneUVD_75EqzUnZ2dnUVZ_gydnZ2d@earthlink.com...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ggogs2$vn$1@news.motzarella.org...
Omer S <oabukovac@earthlink.net> wrote in message


Could you check the URL
www.vaccuumtubefans.org/forums/Topic_12AX7

googling 1 c or cc or subdirectories, or similar domain got nowhere,
unusually. Nothing found via kloth.net domain whois



Try this one!

http://tinyurl.com/4xur8r

Omer
Click to expand...
 
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