You dont want the exhaust temp to get anywhere close to the seal temp!
By that point your seal temp is way past the limit. On an 8877 the seal
temp is rated at 250 deg C max (480 deg F). Id try to keep the exhaust
temp below 300 deg F.
On Wed, Apr 6, 2011 at 6:33 PM, Jeff Blaine <keepwalking188@yahoo.com>wrote:
> RTTY contest duty is the worst for the transformer - not for the tube.
>
> The thermal mass of the transformer is huge and if it starts out with a low
> temp the gradient will keep the innermost windings from
> heating to max in RTTY service until you've been running for an hour or so.
> And as the guys mentioned earlier, any air circulation
> on the transformer (even really minimal levels) will have a huge impact on
> the final temps the tx reaches.
>
> If you want to whack the tube, a good 5 minute RTTY transmission is the way
> to go. The tube heats up to it's max after maybe 15-30
> seconds - just stick a probe and watch the exhaust temps stop rising at
> some point the system is stable and if you have not pushed
> pass the tube op temps (seal limited) then it's probably going to be fine.
>
> 73, Jeff ACØC
> www.ac0c.com
>
> -----Original Message-----
> From: Carl
> Sent: Wednesday, April 06, 2011 7:44 PM
> To: Al Kozakiewicz ; amps@contesting.com
> Subject: Re: [Amps] Alpha vs Henry
>
> Maybe time to see what the anode temperature is but Id think 1000W out
> would
> be fine.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Al Kozakiewicz" <akozak@hourglass.com>
> To: <amps@contesting.com>
> Sent: Wednesday, April 06, 2011 8:35 PM
> Subject: Re: [Amps] Alpha vs Henry
>
>
> > 1500 watts continuous for 30 minutes; 2500 for 30 seconds.
> >
> > Even if I do nothing but call CQ every 2 seconds, that's probably "only"
> > about a 60% duty cycle. I'm just trying to get a feel for how much
> > derating is prudent when using the thing for extended periods of time.
> >
> > 73
> >
> > Al
> > AB2ZY
> >
> > -----Original Message-----
> > From: Carl [mailto:km1h@jeremy.mv.com]
> > Sent: Wednesday, April 06, 2011 5:37 PM
> > To: Al Kozakiewicz; amps@contesting.com
> > Subject: Re: [Amps] Alpha vs Henry
> >
> > What does Ameritron say?
> >
> > Carl
> > KM1H
> >
> >
> > ----- Original Message -----
> > From: "Al Kozakiewicz" <akozak@hourglass.com>
> > To: <amps@contesting.com>
> > Sent: Wednesday, April 06, 2011 5:05 PM
> > Subject: Re: [Amps] Alpha vs Henry
> >
> >
> >> Can anyone tell me how much power an AL-1500 is rated to produce at a
> >> 100%
> >> duty cycle?
> >>
> >> During RTTY contests and outputting about 1000 watts, the tube side of
> >> the
> >> cabinet gets mighty warm. The power supply side seems cool - but then,
> >> that's with the cover on. I don't know how hot is too hot and it would
> >> be
> >> useful to know at least how much continuous power the supply is rated
> >> for.
> >>
> >> Tube cooling is probably another issue...
> >>
> >> Al
> >> AB2ZY
> >> _______________________________________________
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> >> Amps@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
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>
--
Damon Stewart, KJ7E
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