Brymen BM869s might do it, but the specs are indecipherable (to me).
I'm sure #joeqsmith could tell us.
It depends. Switch it to the mV range, the one clamp should kick in. The PTC for that clamp is going to draw some current as it heats up. The signal they are trying to use may not like that load and the meter is certainly not going to like that HV.
In AC or DCV, the clamps wouldn't come into play
(assuming your not a kid playing with a MOT or exceeding the clamping voltage) but the meter may not be able to detect what they are trying to read. If they are looking for volts on top of a few hundred volts, it may be fine.
So, for example.
1) HV supply in series with injection transformer. Supply set to -400VDC. Injecting a 500mV 1KHz sine wave.
2) Left BM869s looking at the output of the injection transformer showing frequency and ACV. Right BM869s reading in DC mode, looking at the DC and AC components. You only have 100mv res in the secondary display.
3) Place Fluke 189 in series with a DC blocking cap. Monitor the voltage across the right BM869s.
4) The Right BM869s is placed in the ACV mode while the Fluke 189 is placed into the mVAC mode. Note the voltage is too low for the BM869s to read it correctly. Also keep in mind that the power supply I am using of course has noise which is mixing with the noise I am injecting.
5) You can see both the Brymen and AC coupled Fluke track.
I played with a lot of tube equipment when I was a kid and just used an analog meter. I don't remember if my old Radio Shack meter had a DC block like that cheap analog meter I chopped up or not. That analog meter did have a separate connector with the cap which I think I integrated with the AC mode.