[Phil Allison[_4_]]

Trevor wrote:




I hope I never, ever have to use a VTVM ever again. I spent more time
balancing and zeroing than taking measurements, it seemed. Modern
high-impedance DMMs make my life so much easier

You could say that about digital CRO's Vs analog ones too. Spent a lot
of time adjusting CRO's before you'd even attempt to use it.


** The exact opposite is true.

Analoge scopes ( CROs to some) are easy and quick to use, no ambiguous stuff on the screen to worry about. With a DSO, one fiddles about with the controls and menus for ever.



To be fair the AVO's were not VTVM's,

** VTVMs waayy outperform AVOs when it comes to electronics, especially with high impedance or valve circuitry.

However, they shine with electrical gear like motors, relays, transformers lighting etc. Old school.


But you did need a VTVM/SSVOM or CRO when loading was a problem.
Not something people often worry about these days with modern digital
multi-meters, even when they should. 10Mohm is a lot better than
20kohm/volt in most cases, but if you are working with Megohm plus
impedances, you still need to know about loading. Amazing how many
people get caught out still.


** Say you have an audio triode valve with 250V on the anode fed from a 470kohm resistor. Both a VTVM and a modern DMM will show 5% or more low on the actual anode voltage. So will a 20kohm/VOM set to its 500V range.


..... Phil