On Thu, 5 Jun 97 15:08:50 -0700 Rich Measures <measures@vc.net> writes:
>>At 01:35 PM 6/5/97 -0700, you wrote:
>The Mu of the Svetlana tube is higher than the SB-220's original Eimac
>
>tube. I would expect that the SB-220's zener will need to shorted to
>
>increase the ZSAC to the needed minimum of 75 mA per anode for linear
>operation. A similar situation should occur in the TL-922. However,
>in
>the L-4, there is no zener to short out, so there may be a problem.
>In
>any event, it should not matter if 600w dissipation tubes are used.
>500w
>of dissipation is more than enough for operation at 4kV at 400mA.
>Another 100w of anode dissipation capability will change nothing.
> Consider that additional cooling air is going to be needed to
>realize
>100w extra dissipation--except perhaps in the SB-220, which has an
>over-supply of cooling air.
>Rich---
While the SB-220 has sufficient air for Tantalum plate tubes, it is
marginal for Graphite. The problem is compounded by age as the original
fan slows down.
I heartily recommend Harbach Electronics high speed fan in any case, it
is cheap insurance.
Since the 220 and most of the other commercial 3-500 amps are power
supply limited, the Svetlana tube may not offer much extra benefit;
unless the price is below the Chinese competition.
73....Carl KM1H
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