Stable 120V AC power supply?

[pcee]

Is there such thing as an inexpensive AC stable power supply?  In the devices I'm testing, the +/- 0.5% variation in mains voltage is causing about a +/- 1.5% variation in measured output.  I'd like to eliminate that variability.

The closest thing I've found is the Instek APS-7050E, but (a) it's still over US$1600, and (b) I can't quite tell if it would actually be an improvement from its specs.  (I'm not sure whether its line regulation spec of 0.1% of full scale is 0.1% of 120V or 0.1% of 500V, and whether that's just accuracy rather than stability.)

Is there a different or a better solution?  The DUTs are generally under 120W max, and usually quite a bit lower.

Would a double conversion UPS tend to be more stable?  These seem to be a bit more affordable, at $600 for the Tripp Lite SU700XLCD or $750 for the Eaton 9SX700, but I don't know if they're necessarily more stable either.

I've even heard discussions of feeding an AWG sine wave into an audio amplifier to produce 120V, but I'm not sure what specs I'd need in such an amplifier or what kind of load it could support.

I'm fine with something secondhand, so long as it produces a steady voltage and frequency even when mains fluctuates.

[bastl_r]

In my reason you will need minimum a calibrator like an old HP745a or similar to reach the accuracy of 0.1%!
Maybee additional with a amplifier.

[Overspeed]

Hello

What current level do you need ?

Regards
OS

[andrewtaylor]

Is there a different or a better solution?  The DUTs are generally under 120W max, and usually quite a bit lower.

I use a sine wave generator followed by a professional audio amplifier with PA output: Klein&Hummel TelewaTT 240 for this work.
It has an internal 100V output transformer output for the 100V ELA lines.
And support a little overdrive to 120V withour distorsion raising too high.

It warks perfect for 50/60/400 hz tests.

more details (use deepl.com if you need  different language):
https://www.radiomuseum.org/r/klein_telewatt_mono_endverstae_6.html

[pcee]

What current level do you need?

Usually 1A or less.

I can imagine going up to 2A for some devices, and I can't imagine ever going above 4A.  So I think a 500VA power source would be more than adequate.

I've seen a few Chroma 6404 and 6504 power sources on eBay that are in the $700-$800 range, would they be a good option?

[mzzj]

Audio amplifier and toroid transformer. If your load has  fixed power consumption you might be able to run it even open-loop. Otherwise you'd need to put the transformer inside some sort of feedback loop.