-
Dear volts masters,
This seller has two pieces to sell and accepts offers, is the price worth for getting one ?
If yes, what caveats and gotchas should I look for ?
If someone from Germany want also one maybe we can organize a trip together, the rest of this week I'm in vacation.
Cheers,
DC1MC
URL:
https://www.ebay-kleinanzeigen.de/anzeigen/s-detailansicht.html?adId=900638436
-
https://xdevs.com/fix/hp3458a/
To me a 3458a <2500€ it's fishy and high risk. 99% the seller is not related to a Lab Cal. Even if you can look at the device in your hands it's a pretty complicated beast, you can not see for example a ppm drift in 1 hour visual inspection.
If you need one, I would go here:
https://www.ab-precision.de/products/used-test-equipment/
and with a decent amount of money you can sleep well after the purchase. Adrian is, as I know , one of the best seller for the 3458a in Europe.
Good Luck.
-
Here is an update, a response sent by the seller to my question about the condition of the devices and calibration status, the original response n German and some quick English translation:
"Hallo, ich habe leider keine Infos zur Kalibrierung oder zu Reparaturen. An den Gehäusen sind auch keine Siegel angebracht, daher kann man auch nicht sagen, ob sie jemals geöffnet wurden. Die Geräte wurden bereits vor einigen Jahren aus dem Betrieb genommen. Seither wurden sie in einem klimatisierten Raum gelagert."
"Hello, unfortunately I have no information about calibration or repairs. There are no seals attached to the cases, so you can not tell if they were ever opened. The devices were taken out of service several years ago. Since then, they have been stored in an air-conditioned room."
So, if the plan A - have a knowledgeable person, with an already existing stack of 3458A's and who knows the platform inside and out, coming together and looking over the devices and saying: "Yes, this one it's worth having for this and that one for that..." coming with me (even if somebody doesn't want yet another 3458A, I can still sponsor a trip to Freiburg if any German voltnut wants to create the seed of a small lab in Mannheim) is not going to happen, what about
plan B - what should I look for and how much should I offer for a device, so that it will be worth having, regardless of (possible) ppm drifts and stuff ?
I mean, yes, it could be that in a strictly climatized room with special probes worth another 2K EUR it may be some observable drift against some 10K EUR instrument or voltage reference, but I don't have such a room or equippment, so what should I look for and how much should I offer to make it a (relatively) safe bet for a beginner voltnut ?
Your knowledgeable opinions are much valued.
Thanks,
DC1MC -
The biggest issue with an apparently working unit that passes selftest is the drifty ADC. Although Agilent states that this issue is confined to a limited set of serial numbers, it also seems to affect older units.
Out of five units some friends and I have, three needed the ADC repaired. However, it might be that the drifty units are recycled through eBay. "Unit powers on but no ability to test"...
Catching a drifty ADC, using the HP procedure (which does not need a stable external reference) takes a week of readings. So you cannot validate the unit with a day trip.
You could measure a stable source; run autocal. If the unit moves 20 - 30 ppm, it may well have a problem. Assuming, of course, that the seller did not pull an autocal recently.
In the US, replacing the ADC runs about $1100 with an exchange. $1600 more gets you the full refurb service. -
Thanks for the hint @martinr33, could you tell me more about the autocal quick test, how should I proceed when I'm there, sorry for my naive question, but up until now such a device was completely outside my price range, to me this a good opportunity to have one, I wold love to not be disappointed. I'm now collecting whatever docs I can and reading threads about it, but it will take a while.
Many thanks,
DC1MCThe biggest issue with an apparently working unit that passes selftest is the drifty ADC. Although Agilent states that this issue is confined to a limited set of serial numbers, it also seems to affect older units.
Out of five units some friends and I have, three needed the ADC repaired. However, it might be that the drifty units are recycled through eBay. "Unit powers on but no ability to test"...
Catching a drifty ADC, using the HP procedure (which does not need a stable external reference) takes a week of readings. So you cannot validate the unit with a day trip.
You could measure a stable source; run autocal. If the unit moves 20 - 30 ppm, it may well have a problem. Assuming, of course, that the seller did not pull an autocal recently.
In the US, replacing the ADC runs about $1100 with an exchange. $1600 more gets you the full refurb service. -
Well, it seem that somebody silently took the risk and bought them both
, I hope if they are OK, and can be resold for 3K+ a piece as "perfectly working", they will at least press the thank you button.
Or at least do a nice teardown and presentation of the "score".
Now please excuse me, I'm going to stay for a while in a fetal position.
DC1MC -
Well, it seem that somebody silently took the risk and bought them both
, I hope if they are OK, and can be resold for 3K+ a piece as "perfectly working", they will at least press the thank you button.
Or at least do a nice teardown and presentation of the "score".
Now please excuse me, I'm going to stay for a while in a fetal position.
DC1MC
Meh, don't about it to much, they could have been 100% but it takes time and equipment to verify that and to be able
to sell it with a profit.
The other way if there was something wrong it would have cost much more time and money.
If I had that type of money to spend on volt-nutting I'd go for a good 6,5 digit meter + fluke 732 and do differential
measurements if I needed that high resolution around 10V.
And perhaps a scanner to data-log multiple diy v-refs.
-
Second the above, having just bought an Ebay "fully tested, removed from working lab" 3458A that is a basket case.
(I got $1900 of my $2750 back, so I'm OK on the finance side, but now I have a project ahead of me...)
In contrast, 6.5 digit meters are readily available, fairly inexpensive, and if you don't know you need the precision, you probably don't. (Each "extra" digit of precision is costly and somewhat maddening.) -
Well, not that I was urgently needing such a precision or have 2K burning my pockets, but I would have enjoyed at least a post thanks from the enterpriser that "snipped" them.
Also to keep the threat at least a bit meaningful, what would be a quick and dirty checklist for such a device for a beginner to at least attempt to verify that is not a full lemon AND don't disclose the sources, as one can see, it's not very safe
.
Like, visual inspection, boards/add-ons to look for and thing like this.
Also I have two 5.5 (6.5 with filtering/averaging) and one 6.5 (7.5 with filtering) devices plus a Datron 1071 that gives signs of life after recapping
, one 3458A would have been mostly for the brag factor, totally useless otherwise, I still do hope the whoever got them will post some nice pictures and how they work.
Cheers,
DC1MC
-
You dont need the 3458A to brag, you need it because of its amazing linearity to check your sanity when working with those calibrators, kelvin varley dividers, references and all that stuff that also wants to be bought and wants to sit in a home with a controlled temperature.
I also bought my 3458A from ab-precision.de and am very satisfied. -
I've kind of wanted to be reasonable satisfied at half the price, what's wrong with that ? But somebody that was less risk averse, jumped and now he'll be satisfied and even make a bit of a profit, or not.
Speaking of metrological things, I plan to get this as a consolation prize, what do you kind sirs say, should I go for it ?
https://www.ebay-kleinanzeigen.de/s-anzeige/genrad-praezisionswiderstandskalbrierdekade-originalzustand-selten/691233775-168-8587
Actually, I do have a need for a nice resistor decade, I was wondering if this boot anchor is worth having ?
Cheers,
DC1MC -
I've been able to pick up two 34401As for $235 and $250 respectively. The one for $235 was one I had passed on until cellularmitosis bought it and offered it to me on a if it doesn't work he would take it basis. It arrived completely wonky, much as I had feared. However, when I opened it up I saw a 1 cm spot of flux residue around one of the LM358s (pure unobtainium now) which had been replaced. On a hunch I cleaned off the flux using a soft brush with isopropyl and it works perfectly. The other one worked flawlessly on arrival. Both have been checked with a DMMCheck Plus and are spot on despite being many years out of cal. The 2nd one only had the original factory cal.
I saw one offered on a mailing list a few days ago for $280 and had to restrain myself from getting a 3rd. They are hard to find under $300+. The one I got for $280 had been up on eBay for a while so I offered $250 and he accepted.
Noise pickup is a *huge* problem at 6.5 digits. It gets lots worse at 8.5 digits. The latter is a more than 160 dB dynamic range.
Right now I'm looking for a good 5.5 digit 3478A for under $125 delivered. I have one, but would like a second. I just bought some 44421A samplers which I plan to use to monitor some $3 AD584JH voltage references to see how well I can forecast aging behaviors. -
That General Radio 1652 A would sure be worth bragging about.
It's more a wheatstone bridge device, not sure if it will work like a completely floating passive resistor decade box wile leaving it
"unverbastelt".
Also beware of unobtanium tubes..
Manual is here:
http://www.ietlabs.com/pdf/Manuals/GR/1652-A%20Resistance%20Limit%20Br.pdf -
In (I guess) all cultures in all times you will find a saying going like:
"Shoot first ask questions later"
I just bought these 4 excellent case/chassis units for USD 50 (in total for all 4):
[Obsolete GPIB extenders]
They are of the same construction as the HP 3456A and similar heavy duty stuff from the 1980ish period - ready (with 120/240v transformer) to be used for (ovenized or not) references, current sources, low voltage amplifier, precision 50/100v DC supply for high ohm measurement, transconductance amplifier, resistance reference or whatever ...
I see other people discuss whether USD 170 or so is OK for a single simple box that is listed elsewhere at USD 250.
Sit on your secrets, do your homework alone, and then come here and ask. -
In (I guess) all cultures in all times you will find a saying going like:
"Shoot first ask questions later"
...
Sit on your secrets, do your homework alone, and then come here and ask.
Yep, that's the modern "community spirit" in many people vision, sounds about right, but not, is 
.
DC1MC -
On the autocal quick test:
Connect the device to a stable voltage source, preferably around 10V. Set yourself up for NPLC 100, and look at the reading. Make sure that the reading is not drifting. It might be noisy.
Then, run the ACAL DCV. Look at the reading again. A good unit should be less than 20ppm off, as long as the temperature is reasonable. A bad unit - if it has not recently been autocal'd - could move hundreds of PPM.
Of course, the seller may have run an autocal beforehand, in which case the test tells you nothing. -
Well, what are you so stupid as to make the link public? You could have asked for our opinion about the devices without showing the link directly. Probably a reseller snatched it. Lesson learned I guess.In (I guess) all cultures in all times you will find a saying going like:
"Shoot first ask questions later"
...
Sit on your secrets, do your homework alone, and then come here and ask.
Yep, that's the modern "community spirit" in many people vision, sounds about right, but not, is .
DC1MC
Of course that's annoying, but did you expect that -just for moral reasons- nobody would bite at a good offer just because you were mentioning a light interest? That would have been pretty naive.
On the bright side, you've saved a lot of money which you can now invest in alcohol and girls. I guess this will be more fun than a Keysight 3458A.
-
@Pinkus, I take offense of being called publicly called stupid by a person who doesn't know me or had any previous contact with me. This is rude and you should take it back
.
On the other side, it could have been some kind of plot to help me not spend some money on TE when there so many fresh girls and slightly used alcohol, or vice-versa
.
Actually, I could make this a habit, each time when I find some nice TE I will publicly announce it, if "some reseller" will get it, it will be for the better, money spared.
To keep it at least marginally related with the subject, what are the most useful options for the 3458A ?
DC1MC -
Well, I am sorry to say that I did not look at the link you provided until now.
Those units were likely a really good deal. The clue is that sticker visible on the top of the unit - that's from a promotion that Agilent ran, and it only appears on units from around 2011 or so. Those units don't have the ADC problem. They don't show up very often. Most eBay units are older HP-badged systems.
A unit like that would fetch $4K on eBay in the USA. -
Hey martinr33, you've been the most helpful guy here, so here is an explicit thanks, the lucky bastard that got them can now rest assured that he just need to list them on evilbay as perfect.
good that you've told me that late, or I would have had some REAL trouble convincing my better half on why do I need another expensive instrument.
On a related note, the offered power supplies are not bad as well
Cheers,
DC1MC
-
How any of this relate to metrology? Buying or not buying used 3458A covered already so many times, in various combinations and outcomes.
-
Hi TiN, in none of the threads that I could find there was a check list for a first time buyer of a 3458A by somebody that didn't already know the platform. The, I would say, more personal question, was from me about the price, that was very low compared with the current prices in Germany and I was wondering if there was some pitfall, it was just a good occasion
.
I was expecting answers similar with:
" See if the S/N is not starting with XXXX as those are bad apples, check to see if the board X and Z are present, option T and W are very useful and while a characterization is difficult to do it quickly, press this and that keys to launch a quick test...", eventually (best outcome) followed by: "hey, good find young Padwan, I knew the device and I'm in Germany, for a price I can come (and get myself another one) and I'll advise you if what is there is worth buying..." .
Question and expected outcome I think it fits fully the forum about Metrology, as this topic devolved in insults and snarky remarks (mostly, there were good contributions as well, thanks guys) I close the thread officially, to not make the a very flat Schnitzel, lesson(s) learned 
.
Cheers,
DC1MCHow any of this relate to metrology? Buying or not buying used 3458A covered already so many times, in various combinations and outcomes.
-
If you'd care to check my article linked from second post in this very thread, you would see what to check and what problems to expect. If that is not extensive enough to you, then no amount internet wisdom would replace doing own research
. I don't know why you still asking questions that are already answered there.
Judging units by S/N does nothing but confusing, as meter with "old" S/N can have very well be maintained by careful lab, and/or replaced new ADC to make sure everything nice and stable, while unit with "new" S/N and Agilent face might be neglected in some humid storage for years and be very much broken.
3458A is NOT the meter on which you come, run some test for a hour and know if "she'll be alright", testing this meter even WITH characterized and known expensive standards like Fluke 732A/B , ESI SR104 will take weeks, just to know if unit have good ADC. And that is not touching ACV/DCI or other testing at all!. -
You can almost get a brand new 34470A for that
I know it's not 8.5 digit voltnut, but still pretty schmick -
I totally agree with TiN.
Only few hobby people can take the risk and buy a cheap 3458a (still 2K€!). Those are the people who have a Lab Cal in the apartment, and have a LOT of knowledge in Metrology.
They can know if the 3458a is a titanic wreck or not, and after at least of some days or logging. Moreover they know if it makes sense to repair it or not.
A simple post here it's not enough sorry. I tend to say in Metrology a simple post is never enough. Metrology is very complicated and require a lot of expensive toys.
OR you are like me and you want to invest money on yourself and your education.
See, I bought a cheap used K DMM7510 (2400€! sooo cheap uh?),
https://www.eevblog.com/forum/buysellwanted/keithley-dmm7510-(not-mine)-ebay-(nleu)/
and not sure yet if it works correctly. Yes it looks good outside and pass all the selftest. It measure ca. 230VAC at the mains and it doesn't smoke. My ref R decade also agrees with the meter R in 2W mode. Well does it drift or not, how stable it is? Is everythining spec.? Dont't F know.
Now I have finally to take out the 7V Ref I bought from TiN in 2015!
https://www.eevblog.com/forum/buysellwanted/(fs)-2-x-ltz1000(a)-ultra-zener-voltage-reference-sale-direct-output/msg624718/#msg624718
and I will start to learn what does it means the ppm stability, maybe raspi log (T and RH) stuff and so on. I want to learn how the stability change when the reference is protected form air, allan deviation? I want to touch with my hands the 1/f noise best spot claimed by the K Rnd at NPLC 5... you name it.
It's an expensive game, but it's so interesting and so eyes opening.
PS: I still have a dismantled silly K2001 in two boxes. I want to improve stability by replacing the the zener Vref, why? I want to learn and see why the K engineers decided to put on the market a DMM with higher noise specs (compare to the K2000). Unique thing in K2001 (as I know) there are 2 Vref inside the K2001 which are somehow connected togheter, and the schematics are there. Perfect territory for me to learn.
And at the end what is blocking me? time, F time! This year I was/am on business trip for 5 months, I am preparing two ironman triathlons and the EE lab comes after that... so sad.
Thank you EEVBlog, TiN, Kleinstein, Dr. Frank, ManateeMafia, High Voltage and all the others Metrology doctors here. You are keeping my EE desire to learn awake.
PSS: I know too many projetcs in parallel.. that's me sorry.