I did some more basic testing last night - the write-up is here:
http://golbornevintageradio.co.uk/forum/showthread.php?tid=5501&pid=69844#pid69844As you'll see, I found a bug when measuring frequency when the selector is set to V (not a problem on the AN8002). It's OK on Hz though. It's not as sensitive as the AN8002. In terms of frequency, it goes out to 80MHz. It might go further, but my RF generator tops out at +17dBm. Joe Smith got 200MHz from the AN8002, but the level wasn't stated.
The amplitude of the square wave is very much equal to the battery voltage.
The AC -3dB point is 3kHz. I did some testing at 100Hz to see how good the RMS converter is. As good as a Fluke 87V, in short. Obviously the Fluke is better at higher frequencies - the AN8002/8 is specified to 200Hz.
As far as I can tell, before these Aneng/Zotek meters came along, this sort of money only got you 2000-count meters, and certainly no sign of true-RMS. These really have shook up the £10-15 market. My AN8002 has been flawless over the last few months, and despite the expected lack of safety features, it appears to be pretty rugged according to Joe Smith's tests. Indeed, it appeared to pass tests that the Fluke 87V didn't. OK, more sampling would be required before anyone reached any conclusions, but first impressions are very positive indeed.
Does anyone know anything about the internal switch? On the AN8002, it's range.