Mine is def an old revision 87V and just giggles at me, displaying
'LOL' when I try to nuke it with GSM, baby monitor, router, transformer, personal vibrator, old noisy electric drills etc
and any other interference I can whip up
(for the noisy suss neighbours) i.e. no problem
I've given up thinking about it,
it works,
it's a Fluke,
and still gets me into work sites I don't belong at, scoring free crew coffee, biscuits and snacks, just by waving it around at the security entrances
Fluke = winner winner vegan dinner