Accurate measurement of filament AC; Inexpensive RMS AC voltmeters

[Naysayer]

Hello All, 10 Meters been open for long distance lately. Made a few jumps over the ocean on 28.420-.450

I’m trying to set filament voltage on my homebrew project. 6vac but I’d like to be more accurate than 10% or half a volt. I have an RCA Voltohmyst Junior I renovated (manual says it’s RMS**) and a cheap Greenlee vom. RCA says 5v and the Greenlee says 7v. I lost confidence in my ability to measure AC and want a 3rd meter to settle the difference and calibrate the RCA.

I see new RMS AC voltmeters on Ebay for $30-40 and they seem to be my best option without paying for a Fluke. Any suggestions on this strategy? I can’t be the first person with this problem yet my online search doesn’t turn up much. Doesn’t everyone own a Fluke? I use a Reference module for DC and it works great for only $15. Ham on a budget......

A low - 0 + mA meter was delivered today so I’m clear to set the screen current and install the new tubes after setting the filament V.
neil, n2eye

** Excellent and detailed walk-thru of the Voltohmyst meters at: https://www.angelfire.com/electronic/funwithtubes/VTVM.html

 

[brandon7861]

If you are going to be using it around noisy electronics, stuff with RFI, anything non-sinusoidal (like half-rectified voltages or square waves), a "True RMS" meter might be the thing you want. They measure a bit differently, taking multiple samples to cancel the effects of noise.