[Amps] General question on filament life

[Gudguyham at aol.com]

In a message dated 2/8/2007 3:25:42 P.M. Eastern Standard Time,  
rbonner at qro.com writes:

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.



I have been thinking about this subject a lot myself.  This is what I  have 
concluded.  Since ham radio is an occasional thing we do with little  transmit 
time compared to off time or listening time.  Seems like it would  be 
senseless to leave your filaments running 24/7.  On the other hand if  you cycled them 
a lot that could be costly too, so for hams as Bob says it  probably makes 
little difference.  But I think the ideal situation would be  to turn off the 
filament when not in use and to bring the filament up slowly  with a variac to 
proper operating voltage every time you use the amp.  It  would be a pain to do 
that every time, but all that hassle aside, it might be  "the best" thing.  
Of course you could argue that one mistake could be  costly, but I am speaking 
only as everything being perfect.  It's just not  practical though.
 
For what is it worth, here is what I do.  When I go on the air I do  not turn 
on the amplifier unless I need to use it.  If I know I am going to  use it, I 
will then turn it on, it will stay on until I am done hamming for that  
session.  I won't shut it off if I know I might be using it again even an  hour 
later like after dinner or something.  I would NOT cycle it on and off  as I 
needed it for a hamming session.  This is why I always put a standby  switch on 
all my SB-220 amps.  Many times I did not use the amp and then  suddenly I would 
and then again I would not.  The standby switch came in  handy so I didn't 
have to cycle the filaments.  You all notice that USUALLY  when a light bulb 
burns out it is when you first turn it on.  Only my 2  cents.  Lou