[NLRS] 4CX250 Testing

[Clair J. Robinson]

This no doubt really brands me as an old-timer, but my 6m, 2m and 70cm
amps all use 4CX250-type tubes. And I have a stock of them that I have
gathered over the years. The only problem has been no knowing what shape
are they in.

I have been gathering parts for a while to make some sort of tester to
rate their relative goodness, but haven't made much progress. Then a few
weeks ago, I found a "dynamic conductance" tube tester at a price that
made the effort of building a tester seem wasteful. So instead I built
an adapter to plug the big tubes into and to supply the necessary 2 amps
of heater current which I didn't think the tester would support.

Good news. The new tubes that I had all tested about the same so I used
them for calibration and then tested all I had. There are now a fair
number of them in the trash. The rest have a relative goodness label on
them.

As I may not be the only one around with this problem, I hereby offer to
test yours if you would like. Please email me your requirements and
maybe I can help you sort out your trash tubes, too.

73, CJ K0CJ