How to test those NOS tubes

I'm not a big tube fan myself but I recall reading somewhere that the performance parameters Mr. Detlof wants to measure are available from a "curve tracer" (one made for tubes of course) which sweeps grid voltage & plots graphically vs. plate current. I believe that these tracers are fairly expensive (cost not justifying return on investment unless you're "in the business") and require a fair amount of electronics knowledge just to operate & also to interpret the "results". Idle noise measurements could be made with a test fixture & a wideband AC voltmeter or scope; don't think that the curve tracer does that too..

Thanks Bob bundus, Dekay, I seee I'm steppping into deep water....

As far as testing tubes, for noise, a George Kaye Noise tester, is the solution. It lets you hear, the actual noise, a tube makes. Most testers, are not reliable, in their noise testing. A better solution, is to match them, with the tester, and then listen to them, in circuit. No tester, can predict, how a tube will act, in every circuit. A tube can be fine, in one amp, and present problems, in another.

Thanks Fletch! In the meantime I've realised this for myself. Throw them into your pre or pre-pre and listen. I've now got a Funke W-19 (Similar to the famous Hickock Cardmatic) where I can match tubes as closely as possible before testing them in the cicuit, where they are to perform. You live and learn. Cheers,

I recently got a VTV tester which lets you listen for noise as well as microphonics. It has been quite an earopener.