Leave them on.
http://www.dailymail.co.uk/news/article-2004797/Worlds-oldest-light-bulb-110-years-old-Livermore-California-station.html
Best 73 de OZ5TG, Verner
> ----- Original Message -----
> From: "Bill Fuqua" <wlfuqu00@uky.edu>
> To: <dhallam@knology.net>; "Ian White GM3SEK" <gm3sek@ifwtech.co.uk>
> Cc: <amps@contesting.com>
> Sent: Sunday, June 17, 2012 4:41 PM
> Subject: Re: [Amps] filament instant heating query / simple remedy
>
>
>> You mean a digital light dimmer.
>> Hey guys, lets not get so carried away.
>>
>>
>> Lets look at other devices that have filaments.
>> The light bulb is a prime example. It has a tungsten filament that is
>> turned on and off more often that your amplifiers. It starts at the
same
>> start temperature and ends up much hotter than your filaments, thus
>> surge current relative to final current ratio is less than that of
your
>> filament.
>> And there is little difference between the (on life) of one left on
and
>> one
>> cycled on
>> and off.
>> It is important to maintain proper cathode temperature to achieve
>> emission and
>> emission.lifetime.
>> The death of a light bulb filament is due to tungsten evaporation, but
>> it has
>> a very thin filament and lower filament temperature. The filaments in
>> your
>> tubes
>> are much thicker. I expect the lifetime for most tubes is due to loss
of
>> emission and
>> not filament life.
>>
>> 73
>> Bill wa4lav
>>
>>
>> At 08:40 AM 6/17/2012 -0400, David C. Hallam wrote:
>>>Has anyone tried an approach like Carel, PC5M, with a microprocessor
>>>controlled soft start for the filament. The microprocessor controls an
>>>optical triac driver The triac is turned on and off over an increasing
>>>portion of the line AC cycle until full on is reached. His
>>>microprocessor program does this in 100 sec. It is designed only for
>>>soft start and does not do any regulation of the filament voltage
after
>>>full output is reached.
>>>
>>>David
>>>KW4DH
>>>
>>>
>>>On 6/17/2012 2:35 AM, Ian White GM3SEK wrote:
>>> > Leigh Turner wrote:
>>> >> That's right Pete, the SB220 had a well designed filament
transformer
>>> >> that self-limited the cold inrush current to a safer value close
to
>>> >> what the tube manufacturer Eimac specified. What the NTC
thermistors
>>> >> do
>>> >> in both the SB220 and TL922 is bring the 3-500Z filaments up in a
>>> >> nice
>>> >> slow and controlled manner.
>>> >>
>>> >>
>>> >>
>>> >> Eliminating the inrush current surge completely like this just
seems
>>> >> so
>>> >> intuitively a good thing to do to mitigate thermal stress on the
cold
>>> >> filament structure.
>>> >>
>>> > But after that initial surge, the truly dedicated obsessive must
move
>>> > on
>>> > to worry about the stability of the filament voltage.
>>> >
>>> > So now our filament supply includes a hot, temperature-variable
>>> > thermistor, connected permanently in circuit... and we are the
group
>>> > who
>>> > can argue for weeks about +/- 0.1 volt.
>>> >
>>> > This should be good ;-)
>>> >
>>> >
>>>
>>>
>>>_______________________________________________
>>>Amps mailing list
>>>Amps@contesting.com
>>>http://lists.contesting.com/mailman/listinfo/amps
>>
>> _______________________________________________
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>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>> -----
>> Ingen virus fundet i denne meddelelse.
>> Kontrolleret af AVG - www.avg.com
>> Version: 2012.0.2180 / Virusdatabase: 2433/5075 - Udgivelsesdato:
>> 17-06-2012
>>
>
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