Agilent 34420A bench meter - is this a good deal?

[vinicius.jlantunes]

All,

I've been offered an Agilent 34420A bench meter and am trying to determine if the offer is a good deal. The seller and I haven't landed on a final price yet, but it's way cheaper than the only similar equipment I found in eBay: this is listed at almost 3kUSD, the one I've been offered is going to cost 300 USD.

http://www.ebay.com/itm/Agilent-HP-34420A-nanovolt-microohm-meter-NIST-cald-/311146394880?pt=LH_DefaultDomain_0&hash=item4871c53500

The one I'm being offered is likely missing its probe and calibration is certainly expired, but other than that should be working fine according to seller. I have done business with this guy before and he is honest.

What you guys think, is it worthy? Seems to be a specialty meter, is it valuable for a hobbyst? What about the probe, assuming it doesn't have one, will it be expensive to get or can I improvise something that will work?

[amiq]

Great meter - at that price it's a steal.

[HighVoltage]

I have been watching the 34420A sales on ebay for a while now. Some have been sold for under $2000 in the last 12 month

The specs of this meter are just really good.
And keep in mind, it is NOT a typical DMM, it can only measure up to 100 VDC
As for the 4W connector, you can get it from Keysight or other places.

But, depending on your hobby, this might be overkill in precision.
May be you also want to look at the Keysight 34461A to 34470A meters.

For the price that was offered to you, I would buy it and sell it and make a good profit to buy a brand new Keysight DMM

[ManateeMafia]

I have two of these meters. I had to repair one but it was listed cheap. They are great meters and will give you the extended ranges most meters are not capable of measuring.

The most expensive part of this meter is the external connector/cable. I bought my cable from Newark and some extra connectors from auctions. The shorting plug and new cable cost almost $300US. My cal lab used the cable as part of its calibration.

I think you should buy it and keep it and post it to the Test Equipment Scores topic.

[Vgkid]

Another vote for picking it up. If you can use it, then keep it. If not sell it for a great profit.

[HighVoltage]

Here is a great Agilent video on the usage of the 34420A to measure the triple point of water.
What an amazing instrument that is, if you need this precision.
Did he say the calibration of the instrument is $ 5000?
Wow!

Agilent 34420A, Measuring the Triple Point of Water]

[ManateeMafia]

I watched that video a couple of times. It makes me laugh every time.  Stan Pond was helpful getting me a manual for a tpw furnace shown in the background.

[HighVoltage]

I watched that video a couple of times. It makes me laugh every time.  Stan Pond was helpful getting me a manual for a tpw furnace shown in the background.

Interesting, that it is called a "tpw furnace", if it cools down.

I also like the rack of what looks like 6 x 3458A's to the right of the bench?

[vinicius.jlantunes]

Thank you all for the answers. Looks like a no brainer then, I will talk to the guy and try to close the deal in the coming days, just sent him an email inquiring about the probe and asking for a few pictures. Will post here if we close the deal.

Thanks again! 

[ManateeMafia]

Interesting, that it is called a "tpw furnace", if it cools down.

Yes it is strange. They actually call it a "Metrology Furnace" http://www.pondengineering.com/Secondary/K34M-C_system_start.html

The 3458A's were definitely hard to miss. I wonder if their placement in the video was intentional on Agilent's part?


Good luck on the meter. Maybe they can also get you some old cal certs if they have them.

[Dr. Frank]

Hi,
I already have seen this video before.. 5000$ is for the calibration of the Triple Point Temperature calibration of the RTD used, not for the 34420A itself.
The RTD sensor costs 3000$..

This lab also calibrates different instruments.. these 6x 3458As are stacked for calibration, I assume..according to the yellow stickers on them

On the left, at 1:15min, you also see briefly an Andeen Hagerling capacitance bridge, very nice instrument also (ppm accuracy).
In the physics institute, we got the early AH2500, 25 years ago..

http://www.andeen-hagerling.com/ah2700a.htm

The 34420A seems to be a wonderful instrument for low level measurements, so a non brainer for 300$.
Anyhow, it's based on the 34401A, but got a better front end... much less noise..
Frank

[HighVoltage]

Hi,
I already have seen this video before.. 5000$ is for the calibration of the Triple Point Temperature calibration of the RTD used, not for the 34420A itself.
The RTD sensor costs 3000$..

This lab also calibrates different instruments.. these 6x 3458As are stacked for calibration, I assume..according to the yellow stickers on them

On the left, at 1:15min, you also see briefly an Andeen Hagerling capacitance bridge, very nice instrument also (ppm accuracy).
In the physics institute, we got the early AH2500, 25 years ago..

http://www.andeen-hagerling.com/ah2700a.htm

The 34420A seems to be a wonderful instrument for low level measurements, so a non brainer for 300$.
Anyhow, it's based on the 34401A, but got a better front end... much less noise..
Frank

It seems like this video was made at the Agilent facility and not the Pond Engineering lab, based on the sign above the 3458A's
Interesting that you recognized Andeen Hagerling capacitance bridge.

Does anyone know of a good quality 4W RTD that is kind of affordable?

[ManateeMafia]

It depends on your range of temperatures and your meter's capabilities. Most meters that take RTDs will support the probes with an alpha=0.00385. I have searched for probes and one of the best 'calibrated' probes is the Fluke 884x-RTD. I think it is industrial grade and it comes with a calibration certificate. It was hard finding any calibrated 4-wire RTD with any cal data. Most start in the $600-700 range and cost almost as much to get calibrated.

I ended up buying a Fluke 5615-12 on Amazon new in box with cal certificate for $350.00. It is advertised as a 5615-9 but they shipped in two different 12" probes after one was returned. The cost to get it calibrated will be much more than what I paid. The 5615 has an alpha=0.003925 which is fine for the tweener or 1521/1522 thermometers.

I think they still have some on their website.

In an effort to stay somewhat on-topic, the 34420 supports 0.00385 and 0.00391. The datasheet states that it uses 0.00385 and 0.00392 which is wrong. I confirmed the typo with Agilent tech support.

[HighVoltage]

Thanks for your answer, ManateeMafia really appreciate the infos on the RTD's,

I looked at the settings for RTD temperature measurements on my Agilent gear:

34461A
RTD,
80 Ohm to 120 Ohm
No alpha setting, no alpha showing

34470A
RTD,
49 Ohm to 2100 Ohm
No alpha setting, no alpha showing

34410A
RTD,
49 Ohm to 2100 Ohm
alpha=0.00385, showing but not changeable

Interesting, that they are not showing the alpha setting on the new 34470A.

It seems the 34420A is the best of all the Agilent meters to make accurate and precise temperature measurements.
Again, $ 300 is an amazing price!
May be you can open it when you get it and show us the inside.