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>To Ian et al,
>The Eimac data sheet says "180 seconds minimum". For
>sure.
>
> >Guess I been lucky. I think so!
> >
>
>The exact warmup time is a judgement call, even by Eimac. If you connect
>a high-resolution DVM across the heater, it acts as its own
>resistance..............
Ian, I have made the same measurement as you outlined and can confirm
exactly what you've noted.
Yes, Bill was a silent Amps member and he often would send me a note in
that regard. Long ago, Bill told me that 3 minutes was a minimum warm up
on the 8877 and he further said that "if you hold the engineers' feet to
the fire, they will tell you that 5 minutes is a better time."
This is hearsay but I have heard that leaving an oxide type heater on low
voltage standby for extended periods is not a good practice. Perhaps
someone here has definite knowledge in that regard/? It would seem logical
that the emitting surface would not be uniform under that condition and
therefore, instant starting immediately thereafter would defeat, in part,
the purpose of a normal warm up.
As you noted, Ian, the long term effects of the standby design of K5AM are
not known but his sample of one is possibly not very definitive, at
best. It would also depend upon the ratio of standby to operate
voltage. That system would probably work well with direct heating type tubes.
73,
Marv, W6FR
>
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<blockquote type=cite class=cite cite>To Ian et al,</blockquote><br>
<blockquote type=cite class=cite cite>The Eimac data sheet says "180
seconds
minimum".
For sure. <br>
<br>
>Guess I been
lucky.
I think so!<br>
><br>
<br>
The exact warmup time is a judgement call, even by Eimac. If you
connect<br>
a high-resolution DVM across the heater, it acts as its own
resistance..............</blockquote><br>
Ian, I have made the same measurement as you outlined and can confirm
exactly what you've noted.<br>
Yes, Bill was a silent Amps member and he often would send me a note in
that regard. Long ago, Bill told me that 3 minutes was a
<u>minimum</u> warm up on the 8877 and he further said that "if you
hold the engineers' feet to the fire, they will tell you that 5 minutes
is a better time." <br>
<br>
This is hearsay but I have heard that leaving an oxide type heater on low
voltage standby for extended periods is not a good practice.
Perhaps someone here has definite knowledge in that regard/? It
would seem logical that the emitting surface would <u>not</u> be uniform
under that condition and therefore, instant starting immediately
thereafter would defeat, in part, the purpose of a normal warm up.<br>
<br>
As you noted, Ian, the long term effects of the standby design of K5AM
are not known but his sample of one is possibly not very definitive, at
best. It would also depend upon the ratio of standby to operate
voltage. That system would probably work well with direct heating
type tubes.<br>
<br>
73,<br>
<br>
Marv, W6FR<br>
<br>
<blockquote type=cite class=cite cite> </blockquote><br>
<br>
<br>
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