23-08-2023, 08:39 AM
Analogue is, of course, excellent for seeing how I or V varies. The bargraph displays on some DMMs are a reasonable substitute.
I've never worked with lots of RF around (though I once did some EMC work on a product that had to be used, I think, at Crystal Palace TX) so am not aware of how it affects DMMs. I know that looking at, for example, the boost voltage on a valve TV can be misleading with some DMMs.
True RMS DMMs, such my Fluke 87, need to be treated with caution when measuring awkward waveforms. A notable recent case was checking the heater voltage on a video monitor. The heater supply was derived from the LOPT and gave daft readings on the 87. I think it was Mark Hennessey who reminded me that my Rigol scope could do RMS voltage measurements and that solved the problem. An AVO would not have helped
Nor would a VTVM. A thermocouple meter would have worked but I don't have access to one.
I've never worked with lots of RF around (though I once did some EMC work on a product that had to be used, I think, at Crystal Palace TX) so am not aware of how it affects DMMs. I know that looking at, for example, the boost voltage on a valve TV can be misleading with some DMMs.
True RMS DMMs, such my Fluke 87, need to be treated with caution when measuring awkward waveforms. A notable recent case was checking the heater voltage on a video monitor. The heater supply was derived from the LOPT and gave daft readings on the 87. I think it was Mark Hennessey who reminded me that my Rigol scope could do RMS voltage measurements and that solved the problem. An AVO would not have helped
Nor would a VTVM. A thermocouple meter would have worked but I don't have access to one.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
