Radio Shack 22-172 DC clamp meter review/teardown

[NiHaoMike]

I recently bought a Radio Shack 22-172 DC clamp meter for automotive work (tracing down the cause of battery draining over a few days in a 2002 Ford Taurus, turns out to be door switch intermittently making contact with door closed). Radio Shack had a sale on that particular meter (normally $70, now $60) and I also had a $10 off coupon, so I got it for $50.




Pros:
* Up to 800A AC or DC current measurement with 10mA resolution on 40A range, all for $50.
* Supposed to be rated for CAT III 600V. The clamp itself has insulated tips.
* True RMS works quite well.

Cons:
* Annoying beep when changing ranges, but continuity mode is so slow as to be nearly useless. (I disabled the buzzer after that.)
* Current range drifts badly, but that might be an inherent limitation of DC current sensing.
* DSP seems to be mounted to the board in a manner similar to how cheap electronics are constructed, but I have seen some high quality devices also using that construction, so I'm not sure what to make of it.
* No RS232 output.
* No wired mA and uA mode, but understandable as that would require an expensive HRC fuse to maintain the CAT III rating.
* There's a thin jumper wire going from the input board to the range switch, would that impact the CAT III rating?

[Omnibro]

I was just gifted one of these on a job yesterday.  It's in very good condition, feels a lot like my 65 dollar Ideal clamp meter.  Very happy to have it, as xraytonyb from Youtube has said, 'he who dies with the most meters wins'