> Applying some high voltage through some sort of current limiting device.
> But it's not simple. You need to apply at least twice the normal high
> voltage of the amp, no RF drive, current limited through a fast high
> voltage fuse, and then adjust bias to control the current... not very
> practical.
A hipot tester shoud spot a gassy tube - you could ask around locally if
anyone has one - or build one.
>
> The original tubes were Eimac, and the guy had a set of new Eimac tubes
> on hand. I put them in, checked the whole beast, replaced a charred
> resistor, then test ran the amp a few hours, trying all bands. But after
> a few months, the guy was back, and again one of the tubes was flashing
> over as soon as about 500 watts were going into the antenna! He had no
> more spares. The non-arcing tubes of the two sets were too different to
> be used together.
Out of interest, in what way were they too different? Did you get a
chance to see if the problem tubes behaved the same in a different amp?
Steve
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