开云体育

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal and
I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy a
new 120,000 count DMM I just can't justify the cost for the hobby type
work that I do. Plus I love working with the older gear and saving money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in the
service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run the
entire cal for each measurement type, If you start with DC you have to
go all the way up the range from millivolts up to several hundred
volts. As we all know it's easy to get a precision calibrated low
voltage references such as a DMM check board, it's another thing to get
500 volts or higher reference at the spec of the meter.

So is this really a meter to buy if your willing to send it off to be
calibrated or have a calibration transfer standard meter that's above
the specs of the 3478A? In other words if all you have is just a few
standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with any
degree of accuracy? Also has anyone found a good source of say 500
volts 60 Hz AC? The right audio amp and a sig gen can get you some of
the other odd cal standards. High voltage DC is just so much easier to
obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who helped
me fix the ROM's.

Jeff

The 3456a was the most accurate in the HP fleet when introduced in 1981. The model line was 345x, so in its heritage was the 3455, 3457, and finally the ersatz standard DMM today, introduced in ~1989, the 3458. HP introduced a high accuracy ADC method, multislope II, with 3456a, you'll see marked change in posted accuracy versus the 3455a. The 3458a further improves that technique. In summary, if you're looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For example, The 56a is as good as the 57a in DCV at 1 year ppm, while the 57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close case calibration and has more unobtanium in its parts list, versus the 56a, which was the last to use all pots based calibration. The basic 57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without shipping, but on the high end with calibration, the 56a runs to $300 while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV bridges in DC, to generate other DC voltages needed to check ranges, but maintaining stability in the reference enough to check the meter's accuracy, is the challenge. Its enough a whole new forum discusses this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>. A similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping key concepts in metrology. A simplest approach is to take your DMM and compare its readings against a known good DMM. The reference DMM should ideally be 4x to 10x more accurate than the DUT. This is the concept of TUR, test uncertainty ratio. When making comparisons, say voltages, the test volt must be stable and precise enough during the transfer, for example if you are checking the 1V range between DMMs, you need to generate a 1V voltage stable to 1uV resolution or less, 1.000 000 VDC. Without a high level of thoroughness and stability, your 6.5 digit DMM will have increasing uncertainty as you get to its LSD.

On the low end of the range, special conditions apply that are fully covered in Keithley's low level measurement handbook, and these need to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is worth it, or should one just take your DUT to the calibrator periodically for $100-$150 to insure your 6.5 digit DMM is as good as you expect it to be.

--- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky <jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal and
I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy a
new 120,000 count DMM I just can't justify the cost for the hobby type
work that I do. Plus I love working with the older gear and saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in the
service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run the
entire cal for each measurement type, If you start with DC you have to
go all the way up the range from millivolts up to several hundred
volts. As we all know it's easy to get a precision calibrated low
voltage references such as a DMM check board, it's another thing to get
500 volts or higher reference at the spec of the meter.

So is this really a meter to buy if your willing to send it off to be
calibrated or have a calibration transfer standard meter that's above
the specs of the 3478A? In other words if all you have is just a few
standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with any
degree of accuracy? Also has anyone found a good source of say 500
volts 60 Hz AC? The right audio amp and a sig gen can get you some of
the other odd cal standards. High voltage DC is just so much easier to
obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who helped
me fix the ROM's.

Jeff

The 3456a was the most accurate in the HP fleet when introduced in
1981. The model line was 345x, so in its heritage was the 3455, 3457,
and finally the ersatz standard DMM today, introduced in ~1989, the
3458. HP introduced a high accuracy ADC method, multislope II, with
3456a, you'll see marked change in posted accuracy versus the 3455a.
The 3458a further improves that technique. In summary, if you're
looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For
example, The 56a is as good as the 57a in DCV at 1 year ppm, while the
57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close
case calibration and has more unobtanium in its parts list, versus the
56a, which was the last to use all pots based calibration. The basic
57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without
shipping, but on the high end with calibration, the 56a runs to $300
while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in
DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV
bridges in DC, to generate other DC voltages needed to check ranges,
but maintaining stability in the reference enough to check the meter's
accuracy, is the challenge. Its enough a whole new forum discusses
this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>. A
similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping
key concepts in metrology. A simplest approach is to take your DMM and
compare its readings against a known good DMM. The reference DMM
should ideally be 4x to 10x more accurate than the DUT. This is the
concept of TUR, test uncertainty ratio. When making comparisons, say
voltages, the test volt must be stable and precise enough during the
transfer, for example if you are checking the 1V range between DMMs,
you need to generate a 1V voltage stable to 1uV resolution or less,
1.000 000 VDC. Without a high level of thoroughness and stability,
your 6.5 digit DMM will have increasing uncertainty as you get to its LSD.

On the low end of the range, special conditions apply that are fully
covered in Keithley's low level measurement handbook, and these need
to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is
worth it, or should one just take your DUT to the calibrator
periodically for $100-$150 to insure your 6.5 digit DMM is as good as
you expect it to be.

--- In hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky
<jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal
and I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy
a new 120,000 count DMM I just can't justify the cost for the hobby
type work that I do. Plus I love working with the older gear and
saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in
the service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run
the entire cal for each measurement type, If you start with DC you
have to go all the way up the range from millivolts up to several
hundred volts. As we all know it's easy to get a precision
calibrated low voltage references such as a DMM check board, it's
another thing to get 500 volts or higher reference at the spec of the

So is this really a meter to buy if your willing to send it off to
be calibrated or have a calibration transfer standard meter that's
above the specs of the 3478A? In other words if all you have is just
a few standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with
any degree of accuracy? Also has anyone found a good source of say
500 volts 60 Hz AC? The right audio amp and a sig gen can get you
some of the other odd cal standards. High voltage DC is just so much
easier to obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who
helped me fix the ROM's.

Jeff

Hi,

I have 2 HP3456A and I really like them.

The HP3456A is a shallow chassis. The HP54111 is about 4 inches longer (part
of that is the rear feet).

I have stacked alot of weight ontop of mine with no trouble. The HP54111
does weigh 59 lbs though...

Ross

-----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: Saturday, December 22, 2012 6:03 PM
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: Re: [hp_agilent_equipment] HP 3456a was Re: HP 3478A general
questions

Wow, thanks for all the info. This will help me make up my mind as to the
direction I go. The boss lady has said no purchases until after x-mas. So
I'm doing my research while I wait. Think I can put the 54111D on top of one
of these without crushing it :)

Thanks,

Jeff

On 12/22/2012 10:17 AM, marvgozum wrote:

The 3456a was the most accurate in the HP fleet when introduced in
1981. The model line was 345x, so in its heritage was the 3455, 3457,
and finally the ersatz standard DMM today, introduced in ~1989, the
3458. HP introduced a high accuracy ADC method, multislope II, with
3456a, you'll see marked change in posted accuracy versus the 3455a.
The 3458a further improves that technique. In summary, if you're
looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For
example, The 56a is as good as the 57a in DCV at 1 year ppm, while the
57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close
case calibration and has more unobtanium in its parts list, versus the
56a, which was the last to use all pots based calibration. The basic
57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without
shipping, but on the high end with calibration, the 56a runs to $300
while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in
DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV
bridges in DC, to generate other DC voltages needed to check ranges,
but maintaining stability in the reference enough to check the meter's
accuracy, is the challenge. Its enough a whole new forum discusses
this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>

<mailto:volt-nuts%40febo.com>. A

similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping
key concepts in metrology. A simplest approach is to take your DMM and
compare its readings against a known good DMM. The reference DMM
should ideally be 4x to 10x more accurate than the DUT. This is the
concept of TUR, test uncertainty ratio. When making comparisons, say
voltages, the test volt must be stable and precise enough during the
transfer, for example if you are checking the 1V range between DMMs,
you need to generate a 1V voltage stable to 1uV resolution or less,
1.000 000 VDC. Without a high level of thoroughness and stability,
your 6.5 digit DMM will have increasing uncertainty as you get to

its LSD.

On the low end of the range, special conditions apply that are fully
covered in Keithley's low level measurement handbook, and these need
to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is
worth it, or should one just take your DUT to the calibrator
periodically for $100-$150 to insure your 6.5 digit DMM is as good as
you expect it to be.

--- In hp_agilent_equipment@...

<mailto:hp_agilent_equipment%40yahoogroups.com>

<mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky
<jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal
and I just don't want to spend the cash to get it back in perfect

spec.

It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy
a new 120,000 count DMM I just can't justify the cost for the hobby
type work that I do. Plus I love working with the older gear and
saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in
the service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run
the entire cal for each measurement type, If you start with DC you
have to go all the way up the range from millivolts up to several
hundred volts. As we all know it's easy to get a precision
calibrated low voltage references such as a DMM check board, it's
another thing to get 500 volts or higher reference at the spec of the

meter.

So is this really a meter to buy if your willing to send it off to
be calibrated or have a calibration transfer standard meter that's
above the specs of the 3478A? In other words if all you have is just
a few standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with
any degree of accuracy? Also has anyone found a good source of say
500 volts 60 Hz AC? The right audio amp and a sig gen can get you
some of the other odd cal standards. High voltage DC is just so much
easier to obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who
helped me fix the ROM's.

Jeff

------------------------------------

Yahoo! Groups Links

The 3456a was the most accurate in the HP fleet when introduced in 1981. The model line was 345x, so in its heritage was the 3455, 3457, and finally the ersatz standard DMM today, introduced in ~1989, the 3458. HP introduced a high accuracy ADC method, multislope II, with 3456a, you'll see marked change in posted accuracy versus the 3455a. The 3458a further improves that technique. In summary, if you're looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For example, The 56a is as good as the 57a in DCV at 1 year ppm, while the 57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close case calibration and has more unobtanium in its parts list, versus the 56a, which was the last to use all pots based calibration. The basic 57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without shipping, but on the high end with calibration, the 56a runs to $300 while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV bridges in DC, to generate other DC voltages needed to check ranges, but maintaining stability in the reference enough to check the meter's accuracy, is the challenge. Its enough a whole new forum discusses this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>. A similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping key concepts in metrology. A simplest approach is to take your DMM and compare its readings against a known good DMM. The reference DMM should ideally be 4x to 10x more accurate than the DUT. This is the concept of TUR, test uncertainty ratio. When making comparisons, say voltages, the test volt must be stable and precise enough during the transfer, for example if you are checking the 1V range between DMMs, you need to generate a 1V voltage stable to 1uV resolution or less, 1.000 000 VDC. Without a high level of thoroughness and stability, your 6.5 digit DMM will have increasing uncertainty as you get to its LSD.

On the low end of the range, special conditions apply that are fully covered in Keithley's low level measurement handbook, and these need to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is worth it, or should one just take your DUT to the calibrator periodically for $100-$150 to insure your 6.5 digit DMM is as good as you expect it to be.

--- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky <jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal and
I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy a
new 120,000 count DMM I just can't justify the cost for the hobby type
work that I do. Plus I love working with the older gear and saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in the
service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run the
entire cal for each measurement type, If you start with DC you have to
go all the way up the range from millivolts up to several hundred
volts. As we all know it's easy to get a precision calibrated low
voltage references such as a DMM check board, it's another thing to get
500 volts or higher reference at the spec of the meter.

So is this really a meter to buy if your willing to send it off to be
calibrated or have a calibration transfer standard meter that's above
the specs of the 3478A? In other words if all you have is just a few
standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with any
degree of accuracy? Also has anyone found a good source of say 500
volts 60 Hz AC? The right audio amp and a sig gen can get you some of
the other odd cal standards. High voltage DC is just so much easier to
obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who helped
me fix the ROM's.

Jeff

Where can you buy one of these for $50?

Bob

I have to say this response has really given me the most food for
thought. It provided exact details about the models and the pro's and
con's of each. It also made me realize something important. There is no
reason I have to buy one of these devices and run out and get it
calibrated. I can make sure it's readings are within reason and take it
out later on to get it calibrated. My main goal is resolution, so I can
have that now and have the accuracy and the resolution later. It will
also give me time to clean up and gain confidence in the device before
spending more money on it.

Very good feedback, Thanks.

Jeff

From: marvgozum <mxg003@...>
Subject: [hp_agilent_equipment] HP 3456a was Re: HP 3478A general questions
To: hp_agilent_equipment@...
Date: Sunday, December 23, 2012, 5:20 AM


eBay, if you're in no rush, patience is rewarded by cheap
buys.? I've tracked 3456a prices on eBay for 4 years,
and the price I posted are ranges I've found.? The
killer is often S&H, as its a wide and heavy beast, but
luckily its short and flat.? Its about the perimeter of
a small coffee table, which makes it easy to stack
instruments ontop of it.

Long ago, this website tracked prices for a lot of good
gear, but its seems to be orphaned.? But it still gives
what hi-lo used to be before 2008, as well as Tektronix.





Many links are broken but you can drill down without a
problem.


--- In hp_agilent_equipment@...,
Bob Albert <bob91343@...> wrote:

Where can you buy one of these for $50?

Bob

------------------------------------

Yahoo! Groups Links


? ? hp_agilent_equipment-fullfeatured@...

Thanks, I guess I will have to just keep looking. For $50 I would love to have one of these, or one of its sister units. And being in Los Angeles, there is always a likelihood I can find one that doesn't have to be shipped.

Bob

--- On Sun, 12/23/12, marvgozum <mxg003@... <mailto:mxg003%40jefferson.edu>> wrote:

From: marvgozum <mxg003@... <mailto:mxg003%40jefferson.edu>>
Subject: [hp_agilent_equipment] HP 3456a was Re: HP 3478A general

questions

To: hp_agilent_equipment@...

<mailto:hp_agilent_equipment%40yahoogroups.com>

Date: Sunday, December 23, 2012, 5:20 AM


eBay, if you're in no rush, patience is rewarded by cheap
buys. I've tracked 3456a prices on eBay for 4 years,
and the price I posted are ranges I've found. The
killer is often S&H, as its a wide and heavy beast, but
luckily its short and flat. Its about the perimeter of
a small coffee table, which makes it easy to stack
instruments ontop of it.

Long ago, this website tracked prices for a lot of good
gear, but its seems to be orphaned. But it still gives
what hi-lo used to be before 2008, as well as Tektronix.





Many links are broken but you can drill down without a
problem.


--- In hp_agilent_equipment@...

<mailto:hp_agilent_equipment%40yahoogroups.com>,

Bob Albert <bob91343@...> wrote:

Where can you buy one of these for $50?

Bob

------------------------------------

Yahoo! Groups Links


hp_agilent_equipment-fullfeatured@...

<mailto:hp_agilent_equipment-fullfeatured%40yahoogroups.com>

You're welcome, and all, enjoy the holidays. It may pay to download the 1993 HP Catalog, that was the last year all in the 345x line were available for sale, so you can compare and contrast the specs, also against the 3478.



The HP manuals, Keithley handbook and the volt-nuts archives are free, just download and search as needed, so you can get all the basic cal and operations info without cost to your misses before you actually buy something ;)

If you intend to stack a lot of gear ontop the 3456a and not sure about weight, put a 2x4 plank so weight get distributed to the edges of the chassis, this is were the most strength lies, while the top and bottom chassis covers are the weakest as there is also no cross bar for structural support. The plank allows a gap for added cooling, even if vents on the 3456a are on the sides and rear, the plank method works for all rack mounted sized gear.

As always too, heavies are best at the bottom, light at the top, as often the boat anchors are also made with stronger chassis to take not just its own weight but others too.

Lastly, I'm not a fan of designs that use battery backed up SRAM for system data, I prefer EEPROM at the least. Since all your purchases are used, the state of the battery is unknown and should be replaced, ASAP. If it snafus, or worst just corrupted, such as in buying "CANNOT TEST" "AS IS" type eBay gear, you'll need budget the possibility of adding $100-140 to your purchase cost to get it formally recalibrated.

With the 3456a, the all pots method puts the user in full control of its cal state, you can cal any range, any time [ keeping metrology guidelines in mind], so if you get one working or not, its also much easier to repair to working order entirely by yourself.

--- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky <jeff@...> wrote:

I have to say this response has really given me the most food for
thought. It provided exact details about the models and the pro's and
con's of each. It also made me realize something important. There is no
reason I have to buy one of these devices and run out and get it
calibrated. I can make sure it's readings are within reason and take it
out later on to get it calibrated. My main goal is resolution, so I can
have that now and have the accuracy and the resolution later. It will
also give me time to clean up and gain confidence in the device before
spending more money on it.

Very good feedback, Thanks.

Jeff

SNIP

In the interest of saving space I'm also looking at the HP 3468a or
3479a. I'm not seeing a major difference between the two except for
perhaps some lower ranges on the 3478a. Any helpful info regarding those
devices.

purchase ?
In the interest of saving space I'm also looking at the HP 3468a or
3479a. I'm not seeing a major difference between the two except for
perhaps some lower ranges on the 3478a. Any helpful info regarding those
devices.

If I can score a 3456a or 3457a for a reasonable price then I'll be
heading that direction. At the moment I'm stuck doing projects with
4,000 count B&K meters and a 20,000 DMM on the Tek 2465 which is not in
cal to it's spec. So my purchases will be pretty soon. I have a Fluke
8010 on the way which I'm sure will also need cal.

Thanks,

If both DMM meet your needs, then the chance it will work coming from unknowns via eBay, and easier to maintain DIY is your goal, the 3456a. If you need more updated features including amps but are willing to risk requiring a factory cal, repair and the costs it requires, 3457a.

3468a is not a system class DMM, but a general purpose DMM very much like he 3478a but is much cheaper as it doesn't support the GPIB bus but uses the then popular HP calculator interface. The 3479a is not a DMM, AFAIK.

--- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky <jeff@...> wrote:Of the two meters, 3456 or 3457 which would be the smarter

purchase ?
In the interest of saving space I'm also looking at the HP 3468a or
3479a. I'm not seeing a major difference between the two except for
perhaps some lower ranges on the 3478a. Any helpful info regarding

those

devices.

If I can score a 3456a or 3457a for a reasonable price then I'll be
heading that direction. At the moment I'm stuck doing projects with
4,000 count B&K meters and a 20,000 DMM on the Tek 2465 which is not in
cal to it's spec. So my purchases will be pretty soon. I have a Fluke
8010 on the way which I'm sure will also need cal.

Thanks,