Extech meter mods?

[ken]

I'm kinda curious... The Extech meter uses frequencies of 120Hz and 1 kHz to measure our pickups. I was wondering if it would be possible or even worth it
to modify it for multiple frequency tests, like say at 500Hz, 5kHz and 10kHz as well?

Ken

[Joe Gwinn]

I'm kinda curious... The Extech meter uses frequencies of 120Hz and 1 kHz to measure our pickups. I was wondering if it would be possible or even worth it to modify it for multiple frequency tests, like say at 500Hz, 5kHz and 10kHz as well?

I would doubt that it's going to be practical. I did open mine for a look. Boards just crawling with tiny surface-mount parts. Computer-driven. And no schematic available. I closed it right up.

The Maxwell-Wein bridge (http://home.comcast.net/~joegwinn/) will work at any audio frequency, and is very accurate. The only problem with bridges is that they are slow to use.

One can sometimes buy used fancy LCR meters that will test at any frequency, or at least many frequencies. The best were made by HP (now Agilent).

Some network analyzers will also work, but require lots of EE knowledge to use. Enough that you could as well build your own LCR meter.

[ken]

Knowledge and time I've got, $$$ is the issue. I'm thinking about prowling electrical surplus stores and see what I find. I thought modding the Extech was going to be a matter of changing a couple of parts in a RC network or something.

Ken

[Joe Gwinn]

Knowledge and time I've got, $$$ is the issue. I'm thinking about prowling electrical surplus stores and see what I find. I thought modding the Extech was going to be a matter of changing a couple of parts in a RC network or something.

If you have time but not money, a bridge is the thing. One can build the bridge quite cheaply. Put the money into a good digital multimeter (such as Fluke) and an analog oscillator (for low distortion). Make sure the DMM can measure resistance, capacitance and frequency.

[ken]

Cool, I have one of those army surplus sine oscillators, extremely stable and built like a tank. I have a Fluke bench meter that can read .001 ohm, I don't know if it can read capacitance or not. I'll have to look.

Thank you,
Ken