Valve testers and E88CC / ECC88 valves

[G3PIJpeter]

Originally Posted by factory

Could that batch be mislabelled?
David

Early on in this saga, I suspected the same and inspected the inside of one of the CV2492s with a x10 hand lens. Each of the pins was connected to the appropriate electrode.

The batch of ten was removed from a 1970s MOD signal generator sub-unit. It might be that they had had a hard life, even though their getters and external condition appeared pristine. All the other examples of E88CC and ECC88 that I have test OK for both triode sections.

Either these CV2492s are a duff lot or they do not have the same electrical characteristics as E88CCs (the commercial equivalent is given as E88CC/01). It might be possible, as suggested before, that these CV2492s give parasitic oscilation on the A2 side. I suppose the real test would be to put one into a working piece of equipment usually fitted with an E88CC - such as a 1950s state-of-the-art 2-metre convertor.

Many thanks for people's continuing suggestions.

- Peter

[John_BS]

What would happen if you connectd the screen to the cathode? i.e. pin 9 to selector 2?