There are several ways to look at how much a grid can take. The energy
perspective is the best I think. Current x voltage x time = energy. Or joules =
watts x seconds. An Eimac engineering bulletin says that the grid of the YC-179
can take max 4 Joules. However, I think that is quite conservative. A LTspice
simulation that I did (posted on my webpage) shows that it is not easy to
quench the PSU with an arcover even with a quite fast crowbar circuit. We know
many amplifier with that tube in amateur service dont use crowbars and have
survived many years and several arcs http://www.lb3hc.net/archives/1171 In case
the Eimac bulletin is correct, that means it can only take 4J = 4W for one
second. I would say 5 times that at least. Possibly more.
73
LB3HC
On 24.03.2013 17:00, amps-request@contesting.com wrote:
> A buddy just fired up his hb YC-156 today. So far, so good. What is the
> max safe grid current for this tube ??
> It has both electronic grid and plate current protection..which can both be
> set to any value. The bias is also
> fully adjustable, so zsac can also be set to any value. The B+ can be set
> to 1/2 or full voltage.
>
> Before the drive is increased, and or B+ is doubled in value, we need to
> know asap, what max grid current is.
>
> Thanks in advance.
>
> Jim VE7RF
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