Is there an official Eimac or other tube manufacturer data sheet that specifies
warm-up/cool-down for a 3-500? I looked at an Eimac 3-500 sheet and must have
missed it?
> From: km1h@jeremy.mv.com
> To: fxb1982@hotmail.com; dave@nk7z.net; amps@contesting.com
> Subject: Re: [Amps] Warm up and on time question...
> Date: Wed, 14 Dec 2011 14:00:08 -0500
>
>
> ----- Original Message -----
> From: "BJ VOUTE" <fxb1982@hotmail.com>
> To: <dave@nk7z.net>; <amps@contesting.com>
> Sent: Wednesday, December 14, 2011 12:38 AM
> Subject: Re: [Amps] Warm up and on time question...
>
>
> >
> > This is what I gather:
> >
> > The AL-82 manual specifies warm up time as "approximately 30 seconds"
> > while the AL-80B manual states "10 seconds". I am guessing that the
> > chimney type cooling VS the muffin fan cooling method accounts for the
> > different warm up times?
>
>
> Nope, different manual writers; 30 seconds is better.
>
>
> >
> > W8JI states that to obtain maximum life from an 8877 tube, not to cycle
> > the heater (filament) excessively. http://www.w8ji.com/8877_failures.htm
> > It stands to reason that this would apply to a 3-500 tube as well.
>
>
> Thats nothing new and just common sense copied from as far back as the first
> AC operated table radio.The military found that out also as the MTBF went
> way up when electronic equipment was left on 24/7.
>
>
> >
> > The QRO HF-2000 manual states: "After prolonged operation, let the
> > Amplifier run for several minutes without drive applied so the fan will
> > cool the tubes before you turn the Amplifier off."
> >
> > When I plan on operating an amplifier for 5 hours I leave it on for 5
> > hours. I don't think turning an amplifier off and then back on after 30
> > minutes constitutes excessive cycling(subjective?), but I consider a tube
> > filament to be like a light bulb and it is said that the life of a light
> > bulb is shortened by cycling.
> >
> > I as well warm up my tube amplifiers for about 5 minutes and let them cool
> > down to what physically feels like idling temperature to me before
> > shutting down. Whether this is necessary or to what extent the tube needs
> > to cool down may likely be a topic of debate but common sense tells me it
> > does not hurt anything.
>
> Anything over 30 seconds is wasting time on direct heated tubes such as the
> 3-500, 572B. 811, etc.
>
> For indirect heated tubes (3CX800, 8874, 8877, etc)follow the tube
> manufacturers specs as amp timer circuits tend to vary in accuracy and with
> age. Anything more than spec is another time waster.
>
> Carl
> KM1H
>
>
>
> >
> > I'm looking forward to more info about this topic.
> >
> > 73, BJ
> > k0cwo
> >
> >
> >
> >
> >
> >> From: dave@nk7z.net
> >> To: amps@contesting.com
> >> Date: Tue, 13 Dec 2011 07:30:30 -0800
> >> Subject: [Amps] Warm up and on time question...
> >>
> >> Hello,
> >>
> >> I have an AL-82, my habit is to turn it on, allow it to warm for about 5
> >> minutes prior to use, use the amp, then turn it back off. Sometimes I
> >> find that I will be using the amp again within 10 or 15 minutes, maybe
> >> 30 minutes. Is it better to leave it on for the half hour, or turn it
> >> off then re power it 30 minutes later.
> >>
> >> Does this cause any issues over the long term? Should I just leave it
> >> on for the half hour? Worried about repeated heating and cooling of the
> >> tubes.
> >>
> >> Dave
> >> NK7Z
> >>
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> >
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