[Amps] General question on filament life

[Robert B. Bonner]

Anyone have a feel for what life one might get out of a set 
of
:: tubes if they left it on for say 12 hours a day most every
: day?
:: Is this "better" than cycling power say 3 times each day ...

***Chops busting time.

OK, Your conditions, I'll restate it again

Now I suppose if somebody would like to send me a stack of new lets say 1000
of each, 3CX800A7's and 4CX800's we could set up an actual laboratory
experiment and run your conditions for the next several years or so until we
have definitive results.

There's a balance here between cycles and constant running.  My guess is
EIMAC hasn't even run those comparison tests to definitive results.  They
know how long they will run when turned on and ran and so does Sylvania
light bulbs as they state the hours right on the box.

How many bulbs have you had fail the first time you turned it ON?  I have
had a lot.  When you are cycling, you will have results all over the map
whether you step start it or not as each tube is an individual.  Some die at
birth, and some live to be 114 years old.

In my experience of 36 years of radio, building with 15 different types of
tubes, owning 20 different types of amplifiers, prototyping several
amplifier projects preproduction and flipping the switch almost everyday....

I'd say, within the conditions you stated, PROBABLY - NO - DIFFERENCE.

Robert B. Bonner Ph.D.

-----Original Message-----
From: Gary Myers [mailto:garymyers at powerc.net] 
Sent: Thursday, February 08, 2007 1:25 PM
To: Robert B. Bonner; 'Amps'
Subject: Re: [Amps] General question on filament life

Thanks - but I don't think it is quite the same as a light bulb 
since the source impedance seen by the filament, especially in 
amps like the Ten-Tec and ACOM where it is controlled inrush, is 
higher than what a light bulb would see... thus my question... 
even the manufacturer will tell you that turning it on and off 
often will reduce the tube life - but no one puts any objective 
values to it - only subjective...

thanks again for your comment Bob.

g.




----- Original Message ----- 
From: "Robert B. Bonner" <rbonner at qro.com>
To: "'Gary Myers'" <garymyers at powerc.net>; "'Amps'" 
<amps at contesting.com>
Sent: Thursday, February 08, 2007 12:19 PM
Subject: RE: [Amps] General question on filament life


: Probably NO DIFFERENCE.  There are some tubes that can only be 
cycled once a
: day, the 3CX800 and 4CX800 arent them.
:
: With any tube, I'd save the big ON switch until you knew you 
were going to
: need it.  Then figure out what the rest of the day was going 
to bring.  Use
: common sense.  Think light bulb they work on the same 
principle.
:
: BOB DD
:
: -----Original Message-----
: From: amps-bounces at contesting.com 
[mailto:amps-bounces at contesting.com] On
: Behalf Of Gary Myers
: Sent: Thursday, February 08, 2007 12:41 PM
: To: Amps
: Subject: Re: [Amps] General question on filament life
:
: Boy - butchered that message (that is what I get for burning
: the
: candle at both ends)... hopefully the message was understood.
: What reduction in life of a set of tubes would one get if they
: left the amp on for 12 - 15 hours per day most every day vs.
: turning it on and off multiple times.
:
: your CONSIDERED comments are appreciated.
:
: g.
:
::
::
:: Anyone have a feel for what life one might get out of a set 
of
:: tubes if they left it on for say 12 hours a day most every
: day?
:: Is this "better" than cycling power say 3 times each day ... 
I
:: realize these are just "general" numbers... but would like to
:: get some thought from the educated. It has been stated that
:: cycling it is not good - but without details of what 
excessive
:: is this is somewhat lacking in true info. Tom ('JI) had said
:: that filaments are rarely the problem... is there any other
:: downside to just leaving it on? [The amp in particular would
: be
:: either using 3CX800's or 4CX800's - Titan vs. Acom2000A]
::
:: thanks for your considerate comments.
::
:: Gary
:: K9RX
::
::
:
:
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