Author Topic: Multimeter Review / buyers guide: HP 3457A  (Read 5084 times)

FOX

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Multimeter Review / buyers guide: HP 3457A
« on: June 02, 2012, 09:37:58 PM »
Hi Martin,
very good Video, keep them coming.
You got yourself a very nice meter.
In case you not aware here the link to the HP Journal Issue from 1986. Page 15 covering the HP3457A how it works and so on
Multimeter Review / buyers guide: Part 2 - HP 3457A
There is also a HP Journal with an big article about the 3458A 8,5Digit Meter if you interested.

The Service Manual including the schematics can be found here
http://www.home.agilent.com/agilent/techSupport.jspx?pid=3457A:epsg:pro&pageMode=MN&lc=eng&cc=US

Noisey Digits and PLCs:
In my opinion the main source off the noise in the reading comes is your power supply, try a battery the reading should be more stable.
The ADCs in this meter are Multislope ADCs (see also Dualslope ADC); the reason why they use powerline cycles for measurement aperture is that, at least in theory, with this type of ADCs, the error from the positive halfwave and the negative should cancel each other out perfectly.
And a multiple number of PLC is of course used too average the result.
A closed Switch should have 0 Ohm or less

MJLorton

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Re: Multimeter Review / buyers guide: HP 3457A
« Reply #1 on: June 04, 2012, 06:39:35 AM »
Hi Martin,
very good Video, keep them coming.
You got yourself a very nice meter.
In case you not aware here the link to the HP Journal Issue from 1986. Page 15 covering the HP3457A how it works and so on
Multimeter Review / buyers guide: Part 2 - HP 3457A
There is also a HP Journal with an big article about the 3458A 8,5Digit Meter if you interested.

The Service Manual including the schematics can be found here
http://www.home.agilent.com/agilent/techSupport.jspx?pid=3457A:epsg:pro&pageMode=MN&lc=eng&cc=US

Noisey Digits and PLCs:
In my opinion the main source off the noise in the reading comes is your power supply, try a battery the reading should be more stable.
The ADCs in this meter are Multislope ADCs (see also Dualslope ADC); the reason why they use powerline cycles for measurement aperture is that, at least in theory, with this type of ADCs, the error from the positive halfwave and the negative should cancel each other out perfectly.
And a multiple number of PLC is of course used too average the result.

Thanks for the feedback Fox.
Yes, I have read that HP Journal Issues...very interesting so thanks for posting here.

I agree about the power supply that could be the source of noise but I seem to have the same "flutter" of the least significant digits with a battery too...but I'll do a better test and comparison soon.

Thanks very much for the info on the multislope ADC...I certainly did not know that.

Cheers,
Martin.
Play, discover, learn and enjoy! (and don't be scared to make mistakes along the way!)

angelico

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Re: Multimeter Review / buyers guide: HP 3457A
« Reply #2 on: June 29, 2012, 07:45:00 PM »
GPI B to USB converter
$50 interface circuit brings 80s/90s edebris to life

Elektor Electronics UK - July/August 2012
http://www.elektor.com/magazines/2012/july-047-august/gee-whiz-a-gpib-to-usb-converter.2188340.lynkx

http://goo.gl/rUooW
« Last Edit: June 29, 2012, 07:49:46 PM by angelico »

MJLorton

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Re: Multimeter Review / buyers guide: HP 3457A
« Reply #3 on: July 02, 2012, 06:51:21 AM »
GPI B to USB converter
$50 interface circuit brings 80s/90s edebris to life

Elektor Electronics UK - July/August 2012
http://www.elektor.com/magazines/2012/july-047-august/gee-whiz-a-gpib-to-usb-converter.2188340.lynkx

http://goo.gl/rUooW

Thanks for that handy info. I will certainly consider going this route as it will certainly add functionality to my 3457A.

Cheers,
Martin.
Play, discover, learn and enjoy! (and don't be scared to make mistakes along the way!)