[Amps] Filament life

[R L Measures]

On Jul 15, 2006, at 3:28 AM, Gudguyham at aol.com wrote:

>
> In a message dated 7/15/2006 1:23:13 A.M. Eastern Standard Time,
> rob at sherweng.com writes:
>
> I was in  commercial broadcasting for about 25 years, and filament  
> life
> was an  issue.  What puzzles me, however, is Alpha's recommendation to
> turn  off their amps if one is not going to use it for two hours.    
> If I
> was going to be operating on and off during a Saturday, for  
> example, my
> inclination would be to leave it on until I was finished operating for
> the day.   Any idea why Alpha says what they do?
>
>
>
>
> I was also under the impression to leave the filaments running.   
> One  of the
> first things I did with the many SB-220's I owned was to add a  
> stand-by
> switch so I would not have to shut down the filaments when I did a  
> bare foot to  KW
> comparison report on the air.  I am sure someone could make an  
> argument
> saying that cycling the filaments is not a problem,but it was  
> always my belief
> that if a good step start was not incorporated in the filament  
> supply that the
> constant cycling could eventually cut down on filament life.

`••••
Lou == The SB-220 uses a current-limiting type filament transformer  
that allows no more than 60% of the 3-500Z's rated filament inrush  
current to flow, so step-starting the filament is unnecessary.   
However, the inrush current to the HV transformer is such that it  
will eventually erode the contacts of the ON/OFF switch, so a step- 
start is still useful.
end
  15 July, 5:46AM

> it is a known
> fact that 99% of light bulbs that burn out, burn out when they are  
> first turned
>  on, a big bright light for a second, and puff dead bulb!  73  Lou
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R L MEASURES, AG6K. 805-386-3734
r at somis.org