HP 3468 voltmeter with HP-IL

[4ster]

Anyone here had experience with the HP's IL voltmeter?

I'm looking at buying a 3468 voltmeter. Since it would be used mostly away from a bench it will have to be battery powered, and that was an option offered by HP. I've only seen one offered with a new main battery. I've also noted that there are A and B models.

If I were to buy one, can all models be upgraded to the battery option? I'm looking at a 3468B right now that is not offered as a battery powered unit. It has been serviced and calibrated with a new lithium backup battery to retain calibration.

HP's battery option sounds like it was a sealed lead acid gel cell. Was it a standard size or will I have to get creative if I get one without a battery?

[Dave Frederickson]

(06-11-2015 03:24 PM)4ster Wrote:  Anyone here had experience with the HP's IL voltmeter?

A number of us have a 3468.

(06-11-2015 03:24 PM)4ster Wrote:  I'm looking at buying a 3468 voltmeter. Since it would be used mostly away from a bench it will have to be battery powered, and that was an option offered by HP. I've only seen one offered with a new main battery. I've also noted that there are A and B models.

The A and B models are identical except for the case. The A model has a carrying handle and the B is intended for bench top / rack mounting.

(06-11-2015 03:24 PM)4ster Wrote:  If I were to buy one, can all models be upgraded to the battery option? I'm looking at a 3468B right now that is not offered as a battery powered unit. It has been serviced and calibrated with a new lithium backup battery to retain calibration.

HP's battery option sounds like it was a sealed lead acid gel cell. Was it a standard size or will I have to get creative if I get one without a battery?

Since the battery option included additional circuitry to charge the battery I think your best bet is to find a 3468A with the battery.

Dave

[4ster]

Thanks! That helps a lot. Now to patiently search....

[Dave Frederickson]

(06-11-2015 04:14 PM)4ster Wrote:  Thanks! That helps a lot. Now to patiently search....

Here's one: http://www.ebay.com/itm/HP-HEWLETT-PACKA...1662671988

Except it's in Singapore.

[gferluga]

Avoid that seller in Singapore... so many troubles with him.
I received a different voltmeter, not calibrated, not as shown.
Calibration is not an easy job.
Hope this help out...

[rprosperi]

(06-11-2015 07:48 PM)gferluga Wrote:  Avoid that seller in Singapore... so many troubles with him.
I received a different voltmeter, not calibrated, not as shown.
Calibration is not an easy job.
Hope this help out...

When doing research when buying mine a bit over a year ago, I did a lot of reading about the calibration issue; my conclusion is this simple advice: if you are capable of performing this procedure to calibrate the DMM, you probably already have something better. So be sure to have seller verify calibration is current, or be sure you have access to calibration-level skills and tools. Boards list story after story of folks getting "real good deals" on 3468's that turned out to be out of cal.

But, you can get lucky and get a good one cheap - patience is the special sause here, as usual.

[Dave Frederickson]

Bob brings up an important point. Some things to consider regarding calibration:

1. Even though the calibration certificate/sticker may have expired it doesn't mean that the measurements are inaccurate.

2. Even though the measurements may be out of spec, the 5.5 digit measurements made by the 3468 are probably more accurate than a calibrated 3.5 digit DMM.

3. If you find a nice DMM at a good price, you can still get it calibrated by a service. Someone on eBay is calibrating 34401's for $98USD.

4. If you have access to a calibrated DMM, compare several measurements to determine the accuracy of the 3468.

Dave

[Paul Berger (Canada)]

The calibration data on these meters and on the 3421A data collection unit (appears to be the same A->D converter) is stored in battery backed RAM. When you get one, it is likely that you will have no way of knowing how long the battery has been in there so it is a good idea to change it. This requires a little soldering and has been discussed on this forum before, see the suggestion from Katie Wasserman at http://www.hpmuseum.org/cgi-sys/cgiwrap/...ead=176914 I did not use clips to connect my temporary battery but tack soldered the connections while I removed the old battery and installed a new one.

[Dave Frederickson]

Well someone just won a 3468A w/ battery option for $88USD. Was it you, 4ster?

[isanchez]

Hi,

I have replaced the batteries in one 3468 and one 3478 (I have put a battery holder and a removable 3V photo battery)..now I am facing how damm to calibrate them...quite difficult even after reading the manteinance manuals...

I have a doubt (well many!) about the callibartion process: Is it necessary to complete the whole callibration process in one session (voltage, current, resistance, etc.), or it can be done partially and done by phases?

Thanks in advance
Best regards

Ignacio

[Dave Frederickson]

(06-15-2015 09:25 AM)isanchez Wrote:  I have a doubt (well many!) about the callibartion process: Is it necessary to complete the whole callibration process in one session (voltage, current, resistance, etc.), or it can be done partially and done by phases?

According to the service manual the calibration procedures must be done in order. This is because the DC current measurements accuracy, for example, depends on the DC voltage measurement accuracy. If the DC voltage procedure calibration procedure is performed, you can't come back in a year and start at the DC current calibration procedure because the DC voltage measurements are no longer accurate.

Now if you want to start the whole calibration process in the morning and then finish after lunch, that's fine. So what exactly do you mean by "phases"?

The big question is, you have access to the required calibration equipment?

Dave

[isanchez]

Hi,
thanks for your answer...
I have read you have to calibrate many variables: ohm, amp, voltage, with different rates or levels...the thing is if it must be done all at one time...or it can be partially done and be re-taken afterwards...(i.e. can I calibrate the resistance and store it, and afterwards callibrate the voltages or intensities?)
Sorry, English is not my native tongue, so maybe I am not expessing myself clearly or, maybe, I don't understand well the calibration process explained in the Service manual.

I have the following equipment required: int/voltage regulable source, multimetre, (access to the resistors proposed in the manual)...maybe something missing? I have just made a first light read of the Service Manual.

Again, thanks for your help.

Kind regards

Ignacio

[Dave Frederickson]

Hi Ignacio,

The thing is, you might have some equipment but it doesn't have the required accuracy. The DC Voltage Standard (power supply), for example, needs to have an accuracy of +/- 0.005% or better. The rule of thumb is the equipment needed should be at least 10 times as accurate as the equipment your're calibrating.

Dave

[4ster]

(06-14-2015 09:20 PM)Dave Frederickson Wrote:  Well someone just won a 3468A w/ battery option for $88USD. Was it you, 4ster?

Nope, missed that one. Still looking.

[Mark Hardman]

I purchased my HP-3468A refurbished and NIST-calibrated from Larry Atherton on eBay. He trades under "la-tech-renewal". He might be willing to provide calibration services for an HP-3468A you purchased elsewhere.

He also sells refurbished HP-85s.

He currently has both an HP-3468A and an HP-3468B on offer. Expect to pay a premium. I'm glad I did.

[I am not affiliated with this seller and trade on eBay as LED.]

[4ster]

(06-16-2015 02:26 AM)Mark Hardman Wrote:  I purchased my HP-3468A refurbished and NIST-calibrated from Larry Atherton on eBay. He trades under "la-tech-renewal". He might be willing to provide calibration services for an HP-3468A you purchased elsewhere.

He also sells refurbished HP-85s.

He currently has both an HP-3468A and an HP-3468B on offer. Expect to pay a premium. I'm glad I did.

[I am not affiliated with this seller and trade on eBay as LED.]

I missed the last one he sold that had the battery option. I was about to pull the trigger but someone beat me to it. I hesitated over the higher price he charged for the unit. As I look into these units I'm thinking his services are worth the higher price.

[isanchez]

Hi Dave,

I understand your comment about the accuracy, thanks!...I use the laboratory equipments at my University Department (Informatics Engineering) (Franckly, I don't know how accurate are they)

The thing is that these equipments for me are just collector's items...I really don't mind at all if they are accuratelly callibrated, but I just want the "error" message deleted. They are not for sale or professionally testing, just be considered collector's items, I insist...

I shall try to go deeper into it during the week-end.

Kind regards


Ignacio

[Sadsilence]

(06-16-2015 05:11 AM)4ster Wrote:  I missed the last one he sold that had the battery option. I was about to pull the trigger but someone beat me to it. I hesitated over the higher price he charged for the unit. As I look into these units I'm thinking his services are worth the higher price.

Sorry I feel it was me. DMM has not arrived, yet, due to customs handling. So far service from that seller has been exceptionally good. I asked for possibilties to use it with 240 VAC voltage net here and he rejumpered/recalibrated it without additional charge.

Regarding battery option: I asked him how easy it is to access battery (with intention to recharge it with an external loader, when there would have been no possibility to jumper HP 3468 for 240 VAC). His reply: Difficult, even for experienced.

More when it is here.

[Artur - Brasil]

(06-15-2015 09:25 AM)isanchez Wrote:  Hi,

I have replaced the batteries in one 3468 and one 3478 (I have put a battery holder and a removable 3V photo battery)..now I am facing how damm to calibrate them...quite difficult even after reading the manteinance manuals...

I have a doubt (well many!) about the callibartion process: Is it necessary to complete the whole callibration process in one session (voltage, current, resistance, etc.), or it can be done partially and done by phases?

Thanks in advance
Best regards

Ignacio

Ignacio, on page 4-12 of service manual, item r, you can read that if you have done one calibration of any constant, you can interrupt the process - of course, if there was a considerable adjustment on that constant and it is used for other measurements, like DC adjustments, you may have erroneous measurings on these other measurements.
Be sure your sources for calibration are very, very stable.
You can get excellent sources from Ebay, like standard resistors and DC sources.
Best wishes from Brazil.
Artur

[Mark Hardman]

(06-16-2015 05:11 AM)4ster Wrote:  I missed the last one he sold that had the battery option. I was about to pull the trigger but someone beat me to it. I hesitated over the higher price he charged for the unit. As I look into these units I'm thinking his services are worth the higher price.

As a forester, you might be interested in the follow story about Larry's work (follow the link to the .pdf):

The QIC and the Dead

"Dr. Norman Pillsbury was an early 9825 user who was recently pulled back into the HP 9825’s orbit by a lawsuit. As a California registered forester, Dr. Pillsbury testified in a woodcutting case. Back in the 1980s, Dr. Forrester got a grant to analyze harvesting volumes from tree cuttings. He developed sophisticated programs on the HP 9825 to estimate the volume of usable wood obtained from tree harvesting. Decades later, his efforts as an expert witness prompted him to rediscover his DC100 tapes, to purchase an old HP 9825, and to try to recover the programs and data from those tapes [With major assistance from Larry Atherton]. His story is fascinating."

Click here to download his story.