Doing some "weeding" of my loose glassware and found a nice PX4 in a box. Tested perfectly for Gm and Ia on the VCM163 but when I switched from "Gm" to "gas", breaker flicked out and blue fault light lit up. Oh dear, too bad, never mind - time to bin it, but I was deeply suspicious as the PX4 showed no sign of blue glow when in the Gm test mode. Tried a new tactic - briefly turn the power off before doing the gas test. No grid current, no gas. no breaker : good tube. What could be wrong with my VCM163?
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C6 a 60uF 250v capacitor will still be charged up and it will make the valve conduct for the wrong reason.
I always power off before switching to Gas Test for this reason.
Nothing wrong with it, mine has done the same since 1970.
I always power off before switching to Gas Test for this reason.
Nothing wrong with it, mine has done the same since 1970.
> Tested perfectly for Gm and Ia on the VCM163 but when I switched from "Gm" to "gas"
I was taught to test Shorts and Gas *before* anything else. Who cares what the Gm is, if the tube is shorty/gassy? And a bad tube can blow-up the tester.
Does your tester manual say some other order?
I was taught to test Shorts and Gas *before* anything else. Who cares what the Gm is, if the tube is shorty/gassy? And a bad tube can blow-up the tester.
Does your tester manual say some other order?