|
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.
|
Input offset current.
-John
============
toggle quoted message
Show quoted text
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number
drift from low mV number and goes up to -8.nnnnn for one meter and the
other meter to -6.nnnn. And then float around there. When I short the
leads at Ohm or Volt setting, they show the near zero and when
disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be
the problem?
Thank you.
|
It is probably not a problem. The input impedance on the low voltage DC ranges is very high (over 10000 MEG ohms), so even 1 pico ampere of bias current would produce over 10mV of apparent input voltage with open terminals.
Try shunting a 10 MEG ohm resistor across the input and see what the DC voltage reading is.
--John Gord
toggle quoted message
Show quoted text
--- In hp_agilent_equipment@..., Michael Hong <mcllhns@...> wrote:
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
|
Normal behaviour. They have VERY high input impedance on the low voltage ranges, so any stray charge can cause a reading.
Dave
toggle quoted message
Show quoted text
-----Original Message-----
From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
------------------------------------
Yahoo! Groups Links
|
So what's a fair price for the 3456A without a known state of calibration? I'm still looking at the 3478A's as well or maybe even the 3468A. Something really intriguing about the 3456A however. I did order one of the fluke 8050A's just because. Found one that was powered on and appeared very clean. Doubt I'll have it before x-mas however. Can one really have too many meters ?
Thanks,
Jeff
toggle quoted message
Show quoted text
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com> [mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
|
Jeff,
Did you get the 8050A with or without Option 01 (internal rechargeable
battery pack)? The battery pack is four 1.2 VDC NiCd batteries, two on each
side of the back of the PCB, that are tabbed together. However, with age,
they can 'leak' and create some problems. Would recommend you check them on
arrival if you got the battery option.
They are great meters and very versatile.
Good luck.
Joe
toggle quoted message
Show quoted text
-----Original Message----- From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of Jeff Machesky Sent: Thursday, December 20, 2012 10:54 PM To: hp_agilent_equipment@... Subject: Re: [hp_agilent_equipment] 3456A Voltmeter So what's a fair price for the 3456A without a known state of calibration? I'm still looking at the 3478A's as well or maybe even the 3468A. Something really intriguing about the 3456A however. I did order one of the fluke 8050A's just because. Found one that was powered on and appeared very clean. Doubt I'll have it before x-mas however. Can one really have too many meters ? Thanks, Jeff On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael
Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
------------------------------------ Yahoo! Groups Links
|
I have too many meters. Well, too many I don't use, like the Ballantine 300, the HP410B, and the Heath AV-3. But I would love a 3456A or similar.
Oh and I have a 5-digit job from about 1962, Electro Instruments .01% with Nixie readout. And a Calibration Standards slideback DC voltmeter.
Bob
toggle quoted message
Show quoted text
--- On Thu, 12/20/12, Jeff Machesky <jeff@...> wrote: From: Jeff Machesky <jeff@...>
Subject: Re: [hp_agilent_equipment] 3456A Voltmeter
To: hp_agilent_equipment@...
Date: Thursday, December 20, 2012, 8:54 PM
So what's a fair price for the 3456A
without a known state of
calibration? I'm still looking at the 3478A's as well or
maybe even the
3468A. Something really intriguing about the 3456A however.
I did order
one of the fluke 8050A's just because. Found one that was
powered on and
appeared very clean. Doubt I'll have it before x-mas
however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance
on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
? ? hp_agilent_equipment-fullfeatured@...
|
About $100 if it's working with unknown calibration from looking at recent
ebay sales. Goldenrubi on ebay has sold a couple that were working and
recently calibrated at $200 obo (he'll take reasonable offers) so I'd say
$200 at the most for a working and recently calibrated unit.
I got a 3455A (note 55, not 56) earlier this year for less than $50
shipped... had a red tag saying it failed cal on 2-wire ohms. Problem was
the front-rear switch. Seems just fine otherwise.
Orin.
toggle quoted message
Show quoted text
On Thu, Dec 20, 2012 at 8:54 PM, Jeff Machesky <jeff@...> wrote: So what's a fair price for the 3456A without a known state of
calibration? I'm still looking at the 3478A's as well or maybe even the
3468A. Something really intriguing about the 3456A however. I did order
one of the fluke 8050A's just because. Found one that was powered on and
appeared very clean. Doubt I'll have it before x-mas however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael
Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
|
To be honest I'm not sure if it has the option or not. I do however have 4 good condition sub-c NiCd's standing by just in case. I'm trying to justify the 3456A. While I do some reasonably complex projects they are all 100% for educational purposes, well in the case of the M&M counter it was to keep me from having to count the things for the holiday party. I have a problem right now with a differential amp that has a mismatched resistor. For some reason those few extra digits just sound like something nice to have to get those resistors next to perfect. But still I'm finding it hard to justify. I suspect 2013 might be a tight year for many of us. I have to wait until after x-mas to see what the wife has acquired for me. I'm hoping for a DDS, if I got something different then I'll have to get one of those first.
Thanks,
Jeff
toggle quoted message
Show quoted text
On 12/20/2012 10:06 PM, J. L. Trantham wrote:
Jeff,
Did you get the 8050A with or without Option 01 (internal rechargeable
battery pack)? The battery pack is four 1.2 VDC NiCd batteries, two on each
side of the back of the PCB, that are tabbed together. However, with age,
they can 'leak' and create some problems. Would recommend you check them on
arrival if you got the battery option.
They are great meters and very versatile.
Good luck.
Joe
-----Original Message-----
From: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Jeff Machesky
Sent: Thursday, December 20, 2012 10:54 PM
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: Re: [hp_agilent_equipment] 3456A Voltmeter
So what's a fair price for the 3456A without a known state of calibration?
I'm still looking at the 3478A's as well or maybe even the 3468A. Something
really intriguing about the 3456A however. I did order one of the fluke
8050A's just because. Found one that was powered on and appeared very clean.
Doubt I'll have it before x-mas however. Can one really have too many meters
?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael
Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
|
Thanks Orin, couple of them on the bay right now with 10k resistors connected up. $275 is what the seller is asking. Seams a bit steep. Granted there is some kind of confidence that they are working correctly based on the readings. I can get a nice pretty battery sucking OLED Agilent handheld for a little over $400 with an NIST calibration report. Hmmm. None of it is really needed, but we all love our toys.
Thanks,
Jeff
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Show quoted text
On 12/20/2012 10:13 PM, Orin Eman wrote:
About $100 if it's working with unknown calibration from looking at recent
ebay sales. Goldenrubi on ebay has sold a couple that were working and
recently calibrated at $200 obo (he'll take reasonable offers) so I'd say
$200 at the most for a working and recently calibrated unit.
I got a 3455A (note 55, not 56) earlier this year for less than $50
shipped... had a red tag saying it failed cal on 2-wire ohms. Problem was
the front-rear switch. Seems just fine otherwise.
Orin.
On Thu, Dec 20, 2012 at 8:54 PM, Jeff Machesky <jeff@... <mailto:jeff%40codebest.com>> wrote:
So what's a fair price for the 3456A without a known state of
calibration? I'm still looking at the 3478A's as well or maybe even the
3468A. Something really intriguing about the 3456A however. I did order
one of the fluke 8050A's just because. Found one that was powered on and
appeared very clean. Doubt I'll have it before x-mas however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
|
Gang...
Well for my money, the 3456A is the best DMM HP ever made. While there are ones with more digits, the 3456A has outstanding stablity. Another is the front panel math functions that let you quickly dial up averages and dB conversions. I like it better than the 34401A of which I have two...
Dan in Chandler, AZ
Happy Holidays...
|
I have over 40 multimeters, from a 1948 GR1800A upto some 7.5 digit meters. Also nuldetectors, electrometers, sourcemeters ect.
So i do not think you have to many meters.
On topic, that is normal behaviour. On some meters pretty annoying, like my keithley 199 in autorange, click, click, click so I'm glad it does not start in autorange.
Fred
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Show quoted text
--- In hp_agilent_equipment@..., Bob Albert <bob91343@...> wrote:
I have too many meters. Well, too many I don't use, like the Ballantine 300, the HP410B, and the Heath AV-3. But I would love a 3456A or similar.
Oh and I have a 5-digit job from about 1962, Electro Instruments .01% with Nixie readout. And a Calibration Standards slideback DC voltmeter.
Bob
--- On Thu, 12/20/12, Jeff Machesky <jeff@...> wrote:
From: Jeff Machesky <jeff@...>
Subject: Re: [hp_agilent_equipment] 3456A Voltmeter
To: hp_agilent_equipment@...
Date: Thursday, December 20, 2012, 8:54 PM
So what's a fair price for the 3456A
without a known state of
calibration? I'm still looking at the 3478A's as well or
maybe even the
3468A. Something really intriguing about the 3456A however.
I did order
one of the fluke 8050A's just because. Found one that was
powered on and
appeared very clean. Doubt I'll have it before x-mas
however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance
on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
? ? hp_agilent_equipment-fullfeatured@...
|
I paid 100$ for mine abour 2 years ago. Love it because of the front-panel math and use it over my Fluke 8085A -- Anders Gustafsson Engineer, CNE6, ASE Pedago, The Aaland Islands (N60 E20) www.pedago.fi phone +358 18 12060 mobile +358 40506 7099 fax +358 18 14060 Jeff Machesky <jeff@...> 2012-12-21 06:54 >>>
So what's a fair price for the 3456A without a known state of calibration?
|
I'll say- I have one of the first HP nixie DC voltmeters (I forget the number); in auto mode it constantly cycles. I only keep it because it works flawlessly and it was the first piece of HP gear I acquired. -Dave On some meters pretty annoying, like my keithley 199 in autorange, click, click, click so I'm glad it does not start in autorange. Fred --- In hp_agilent_equipment@... , Bob Albert <bob91343@...> wrote:
I have too many meters. Well, too many I don't use, like the Ballantine 300, the HP410B, and the Heath AV-3. But I would love a 3456A or similar.
Oh and I have a 5-digit job from about 1962, Electro Instruments .01% with Nixie readout. And a Calibration Standards slideback DC voltmeter.
Bob
--- On Thu, 12/20/12, Jeff Machesky <jeff@...> wrote:
From: Jeff Machesky <jeff@...>
Subject: Re: [hp_agilent_equipment] 3456A Voltmeter
To: hp_agilent_equipment@...
Date: Thursday, December 20, 2012, 8:54 PM
So what's a fair price for the 3456A
without a known state of
calibration? I'm still looking at the 3478A's as well or
maybe even the
3468A. Something really intriguing about the 3456A however.
I did order
one of the fluke 8050A's just because. Found one that was
powered on and
appeared very clean. Doubt I'll have it before x-mas
however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance
on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
hp_agilent_equipment-fullfeatured@...
[Non-text portions of this message have been removed]
|
The nice big old lab/bench type DMMs will usually be a good deal in terms of performance v. price, since most people are looking for more modern, smaller types. Unless you plan to become a volt-nut, you likely won't need to go beyond six digits of resolution, so DMMs in the HP3456A class are just right for the top-end of a home lab, and can be used as the standard to calibrate all lesser equipment.
I have a 3456A, but I prefer the 3455A - I recently added a second, fixed with a simple repair. I've collected these over several years, and some Fluke 8400A five digit models, and a couple of Dana five digit ones. As I recall, I paid around USD30 to USD75 for the HPs in unknown working condition (they were OK or needed only minor repairs), and about USD5 to USD15 for the others.
The HPs usually sit on the shelf, to be brought out only for high precision work. The Flukes are the workhorses, used all the time for bench stuff. The most used, however, are those $3 handheld, disposable ones from Harbor Freight - good enough for routine work, and when in doubt, double checked with a Fluke.
So, portability is important, but it's nice to have at least one really high performance lab/bench unit available.
If you read entirely message #48085 from a couple of weeks back, you will see some more detailed discussion of DMM issues. Note that this thread was about the HP34(65)A - a crappy 4.5 digit model - not to be confused with the HP34(56)A, the nice 6 digit one presently discussed.
Ed
toggle quoted message
Show quoted text
--- In hp_agilent_equipment@..., Jeff Machesky <jeff@...> wrote:
So what's a fair price for the 3456A without a known state of
calibration? I'm still looking at the 3478A's as well or maybe even the
3468A. Something really intriguing about the 3456A however. I did order
one of the fluke 8050A's just because. Found one that was powered on and
appeared very clean. Doubt I'll have it before x-mas however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
------------------------------------
Yahoo! Groups Links
|
The low ohms 4-wire for the HP3456A is excellent.
I've 2 of the HP3456a, one in cal from a medical company in Minnesota cost me $200, another from an auto-electronics firm in michigan was only $50.
toggle quoted message
Show quoted text
--- In hp_agilent_equipment@..., "Ed Breya" <edbreya@...> wrote:
The nice big old lab/bench type DMMs will usually be a good deal in terms of performance v. price, since most people are looking for more modern, smaller types. Unless you plan to become a volt-nut, you likely won't need to go beyond six digits of resolution, so DMMs in the HP3456A class are just right for the top-end of a home lab, and can be used as the standard to calibrate all lesser equipment.
I have a 3456A, but I prefer the 3455A - I recently added a second, fixed with a simple repair. I've collected these over several years, and some Fluke 8400A five digit models, and a couple of Dana five digit ones. As I recall, I paid around USD30 to USD75 for the HPs in unknown working condition (they were OK or needed only minor repairs), and about USD5 to USD15 for the others.
The HPs usually sit on the shelf, to be brought out only for high precision work. The Flukes are the workhorses, used all the time for bench stuff. The most used, however, are those $3 handheld, disposable ones from Harbor Freight - good enough for routine work, and when in doubt, double checked with a Fluke.
So, portability is important, but it's nice to have at least one really high performance lab/bench unit available.
If you read entirely message #48085 from a couple of weeks back, you will see some more detailed discussion of DMM issues. Note that this thread was about the HP34(65)A - a crappy 4.5 digit model - not to be confused with the HP34(56)A, the nice 6 digit one presently discussed.
Ed
--- In hp_agilent_equipment@..., Jeff Machesky <jeff@> wrote:
So what's a fair price for the 3456A without a known state of
calibration? I'm still looking at the 3478A's as well or maybe even the
3468A. Something really intriguing about the 3456A however. I did order
one of the fluke 8050A's just because. Found one that was powered on and
appeared very clean. Doubt I'll have it before x-mas however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
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Thank you all for your inputs.
toggle quoted message
Show quoted text
--- In hp_agilent_equipment@..., Michael Hong <mcllhns@...> wrote:
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.
[Non-text portions of this message have been removed]
|
Are you aware the very cheap DMMs are often only 1 Meg input resistance
instead of the 10 meg in better meters. They can still be very useful as
long as you realize they can load a high impedance circuit.
Don Black.
toggle quoted message
Show quoted text
On 22-Dec-12 3:21 AM, Ed Breya wrote:
The nice big old lab/bench type DMMs will usually be a good deal in
terms of performance v. price, since most people are looking for more
modern, smaller types. Unless you plan to become a volt-nut, you
likely won't need to go beyond six digits of resolution, so DMMs in
the HP3456A class are just right for the top-end of a home lab, and
can be used as the standard to calibrate all lesser equipment.
I have a 3456A, but I prefer the 3455A - I recently added a second,
fixed with a simple repair. I've collected these over several years,
and some Fluke 8400A five digit models, and a couple of Dana five
digit ones. As I recall, I paid around USD30 to USD75 for the HPs in
unknown working condition (they were OK or needed only minor repairs),
and about USD5 to USD15 for the others.
The HPs usually sit on the shelf, to be brought out only for high
precision work. The Flukes are the workhorses, used all the time for
bench stuff. The most used, however, are those $3 handheld, disposable
ones from Harbor Freight - good enough for routine work, and when in
doubt, double checked with a Fluke.
So, portability is important, but it's nice to have at least one
really high performance lab/bench unit available.
If you read entirely message #48085 from a couple of weeks back, you
will see some more detailed discussion of DMM issues. Note that this
thread was about the HP34(65)A - a crappy 4.5 digit model - not to be
confused with the HP34(56)A, the nice 6 digit one presently discussed.
Ed
--- In hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky
<jeff@...> wrote:
So what's a fair price for the 3456A without a known state of
calibration? I'm still looking at the 3478A's as well or maybe even the
3468A. Something really intriguing about the 3456A however. I did order
one of the fluke 8050A's just because. Found one that was powered on
and
appeared very clean. Doubt I'll have it before x-mas however. Can one
really have too many meters ?
Thanks,
Jeff
On 12/20/2012 9:42 PM, David C. Partridge wrote:
Normal behaviour. They have VERY high input impedance on the low
voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of
Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the
number drift from low mV number and goes up to -8.nnnnn for one meter
and the other meter to -6.nnnn. And then float around there. When I
short the leads at Ohm or Volt setting, they show the near zero and
when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What
seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
|
Agreed, winter here, humidity < 20% and insane static levels. A 3456A
can read multiple volts on open terminals around here.
Short the terminals with a short section of small (say 28ga) solid
copper wire.
If it it settles on the 100mv range (-3) with a pos or neg reading of
all zeros but for the last two you are in good shape. If the last 2 are
between - or pos 22 max (+/- 2.2uv) you are within factory spec on DC
bias. Expect some noise on the last digit (.1uv per).
My best unit has a positive bias of .4uv, with +/- .1uv noise (a reading
or 2 once or twice a minute).
The worst has a - bias of 1.8uv with +/- .2uv constant (every few
seconds) noise.
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Show quoted text
On 12/20/12 7:42 PM, David C. Partridge wrote: Normal behaviour. They have VERY high input impedance on the low voltage ranges, so any stray charge can cause a reading.
Dave
-----Original Message-----
From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] 3456A Voltmeter
Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.
I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
|
David C. Partridge
Anders