HP/Agilent 34401A, possible to run it battery powered?

[SharpEars]

I was wondering, to get true power line isolation, it makes sense to power a DVM from battery power. Has anyone done any sort of mod the the 34401A to make it battery powered. I am not sure how the PLC (power line cycles) would work in this case, though.

[VK5RC]

Won't this reduce accuracy considerably? I thought the idea of  PLC was to reduce the deleterious effect of mains 'hum' everywhere. If you "isolate" the meter, it won't be able to synchronise with and then 'average out' the mains hum. (my dumb terms!!!!)
I also thought they were truly floating dmms, the measuring inputs independent from mains.

[SharpEars]

Won't this reduce accuracy considerably? I thought the idea of  PLC was to reduce the deleterious effect of mains 'hum' everywhere. If you "isolate" the meter, it won't be able to synchronise with and then 'average out' the mains hum. (my dumb terms!!!!)
I also thought they were truly floating dmms, the measuring inputs independent from mains.

Hmm, you have a good point and I hadn't though of that. Strange to think that a battery powered unit that is totally isolated from mains would have more noise than a mains powered unit.

[VK5RC]

The way I think of it. it is not white noise, it is quite ordered i.e. 50 or 60 Hzso you can "allow" for it to some degree. Filtering or averaging over an integer number of PLC, phase coherent.