[Amps] General question on filament life

[Gary Myers]

I had responded to one individual offgroup... I am self employed and have 
the ability to monitor the bands all day... thus the ability to work someone 
if I so choose... Since moving to AZ, or more importantly since getting back 
on the air after a 15 year absence last year - from AZ for the first time, I 
decided to kind of half-heartedly do DXCC over again from here just for my 
own personal kicks... thus there are times when there is a new band-country 
available (if it is new the amp goes on - period) that I might decide to try 
for or might decide not to ... based often on the lack of desire to cycle 
the amp (and yes I do work a great deal without the amp). Thus my questions 
basis ... better just to leave it on or is it less harmful, compared to the 
first option, just to cycle it several times during the day? [I always let 
it cool down completely before shutting it down].

...and the 3 minute time delay on the amp comes in here as well - begging 
for the "leave it on" scenario - I have lost opportunities due to this wait 
time more often than one would think!

the more general result of this conversation - if there is an objective 
result - is to aid others in knowing the answer as well... instead of being 
told "don't cycle your amp too much"!

g.


  ----- Original Message ----- 
  From: Gudguyham at aol.com
  To: rbonner at qro.com ; garymyers at powerc.net ; amps at contesting.com
  Sent: Thursday, February 08, 2007 4:30 PM
  Subject: Re: [Amps] General question on filament life


  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