[AMPS] re:On-off, or leave it on?

[nospam4me@juno.com]

Just my two cents.  
-
I have many a power device with direct and indirectly 
heated filaments/cathodes, in applications at my work, 
where the typical hours of the device service life are 
metered and logged. 
-
I would often see just about the mfgrs rated life span in 
applications where filament power (well regulated) 
remained on constant.  Replacement of these devices 
are most often done when emission drops below usable 
values. 
-
The same type of application where the power was 
shut off, then reapplied for each machine use reached 
similar emission life span numbers, but there was a 
very significant increase seen in filament failures.  
My personal equipment log shows that value to be in 
excess of 30% 
-
Comments made by Mauri I4JMY in a 12/31/00 post 
hit home with my personal conclusions. I've come up 
with my own fix. 
-
I have installed filament "trickle current circuits" in 
some of my applications.  It amounts to a relative 
trickle current-to-rated filament power applied 
all the time. Filament ramp up circuits are also 
installed in my/our very large applications. I would 
like to write that I've arrived at some rule of thumb 
formula for all circuits, but life is just not that 
simple. 
-
The end results have been very encouraging. Time 
and the log books will tell.  The preliminary results 
are almost no lost filaments before the device 
emission drops. 
-
Another side bar are the very interesting Semens 
series lead installed hour meters installed in some 
of these costly new/replacement devices I/we 
purchase. 
-
Almost all the exact filament on time is shown on a 
really cool slide display that looks like a thermometer. 
As far as I know, the display cannot be reset.  
-
cheers
skipp 
-
nospam4me@juno.com
-

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