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Old 14th Aug 2017, 9:58 am   #73
trh01uk
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Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,648
Default Re: Free Standardised Valves

And we might usefully debate what level of accuracy is acceptable for a VCM?

For the average user who is just trying to get kit working at all, then I doubt whether accuracy is of any importance at all. All they really need to know is does the valve heater still work, and does it have any emission? The go/no-go test indications are quite good enough for that level of testing.

Those (few) of us who are analysing circuits and trying to understand why an equipment does/does not meet its specification is surely going to want something a lot better than that. A starting point might be to note that most valve circuits have passive components with tolerances of +-10%. Occasionally you get circuits with passives down in the 1 to 2% region, but they are not typical.

That observation suggests to me that valve measurements that are better than the circuit tolerances is what is required. So I would be aiming for +-5% on a VCM, with a worst case of +-10%. Probably most helpful is to know where one's VCM is inaccurate, so that one is forewarned not to rely on its results.

Richard

Last edited by trh01uk; 14th Aug 2017 at 9:59 am. Reason: Missing words
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