My thanks to all that responded both on and off list.
Best,
va7vv - jerome
On Mon, 07 Sep 2009 09:13:00 -0700, jerome schatten <romers@shaw.ca>
wrote:
> 1. How to tell if the 813 has graphite or tantalum plates? I have
> one
> pair from the early '40's and one pair made in the early 60's; I
> rotate them every year or so.
>
> 2. Amp runs only on 80/40/30m at 2200v, grids strapped to chassis;
> zero bias; no suppressors. The pi output circuit uses a very robust
> variable inductor (square copper wire) that progressively shorts out
> un-needed turns. Does it make any difference which end (plate or
> load)
> the shorting of the turns takes place?
>
> 3. Fan sucks the hot air out from the top right above the tubes;
> should I be blowing air in instead?
>
> All these things I never thought about when I built it almost 50
> years
> ago.
>
> jerome - va7vv
>
>
>
>
> On Mon, 07 Sep 2009 08:24:38 -0700, Carl <km1h@jeremy.mv.com> wrote:
>
>> There are some running 813's at over 3kv daily on AM; I didnt ask if
>> it is
>> graphite or tantalum plates. I run close to that with graphite
>> plates and
>> never a hiccup.
>>
>> IMO, the 813 is a highly underated tube and Pd with a bit of air is
>> easily
>> 250W.
>>
> [...]
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