On Mar 4, 2006, at 3:44 AM, Peter Chadwick wrote:
> If the tubes are soft, there will be (usually) a blue glow between
> electrodes when drawing current (I have seen it tend more to purple).
Low emission causes gas ionization?
> The emission could be down, which would explain the problem: you could
> maybe rig up a pulse tester, and pulse the grid positive and measure
> the plate current. That could be done with a series load resistor
> 91000 or 1500 ohms at 50 watts, rated for lots of volts!) in place of
> the RF choke and tank circuit and pulse circuit, and pulse the
> filament negative by about 70 volts for a 10ms or so. See what the
> plate current is. All seems a bit messy, though....
>
> 73
> Peter G3RZP
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>
Rich Measures, 805.386.3734, AG6K, www.somis.org
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