On 4/11/20 11:50 AM, Tam Hanna wrote: Yeah, thats the spirit. Take it all off line, so that the next dude who
stumbles across a 4195A can resume operations by scratching his balls. Well first of all, any self-respecting man is going to do that anyway, realistically. I am willing to help out, to try and source stuff from the Western
German, to do measurements on my own 4195A, anything. But PLEASE, let us
keep it online on the list.
People can, and do, die, thereby making their knowledge unavailable. I,
for one, am pretty close - domestic warfare, as my adoptive kid calls
it, is starting to wear me down. Despite all the money I've paid to hit men trying to eradicate them, there are still a few topic nazis on this list. I say this wearing my "one of the moderators of this mailing list" hat. Now that's not to say the topic of getting HP computers set up to run HP software to work on HP test equipment is anything but 100% kosher squarely on-topic here...it is. But there are a number of old farts (even older than you and I!) among us who seem to cling to the erroneous belief that everyone here is a hobbyist playing in their garage, and therefore obviously excludes anything that might need computer assistance to calibrate. So yes, keep such discussions here. Getting HP-9000s set up properly to run the software in question is not always easy, and many of us would benefit from having such discussions live on in the list archives. I'm off to spend the rest of the day cleaning up tornado damage at the museum. Maybe when I'll come back, installing RMB on an HP-9000 will be a solved (and archived!) problem. =) -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: non-profit engineering
Cry me a river. In Europe, we have worked under - and circumvented - customs for like 40 years. There is a lot you can do to "reduce" the value of the shit being shipped. Many things are totally legal, even.
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
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On 2020. 04. 11. 3:11, Dave McGuire wrote: On 4/10/20 9:06 PM, John Griessen wrote:
On 4/10/20 7:07 PM, Dave McGuire wrote:
?? Well that's for the museum, not for my company, but yes.
?? Anymore, in this society, if I'm walking down the street and pass a
guy wearing a tie, I check to see if I still have my wallet. I'm thinking of doing a 501-c for everything I do...
What big profit was I making as sole proprietor anyway? Ahhh. Well that would be pretty tough for me to get away with; I run
it as a company and this is how I feed myself and my family.
Though the way things have been since Der Trumpf's damn tariffs, it
may as well be registered as a "non profit". I can design stuff for
people, but now nobody has any cost-effective way to get it
manufactured! This has stopped the Pittsburgh tech startup scene (my
core business) in its tracks.
-Dave
|
Yeah, thats the spirit. Take it all off line, so that the next dude who stumbles across a 4195A can resume operations by scratching his balls.
I am willing to help out, to try and source stuff from the Western German, to do measurements on my own 4195A, anything. But PLEASE, let us keep it online on the list.
People can, and do, die, thereby making their knowledge unavailable. I, for one, am pretty close - domestic warfare, as my adoptive kid calls it, is starting to wear me down.
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
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On 2020. 04. 10. 22:47, Bruce wrote: Be happy to help - lets talk off line.? I have a working 900/300
system with HPIB, basic and HP UX, needing only a color monitor (have
the B/G monitor).
Do you have a favorite imaging software?? I've been using a program
called Omniflop - seems to archive just about any format I've run into.
Anyway, contact me off line for more discussion.
Cheers!
Bruce K9BC
bruce@...
H
Quoting Dave McGuire <mcguire@...>:
Yup, definitely interested.? It's a lot of stuff and I'm spread a bit
too thin.
??????? -Dave
On 4/10/20 3:53 PM, Bruce wrote:
Put me on the list to notify as you get to them.? I could help if you
are interested in help.
Cheers!
Quoting Dave McGuire <mcguire@...>:
On 4/10/20 3:16 PM, Bruce wrote:
I'd like to correspond off line about how you did the translation.? I'd
like to do the same for the 8340 and some other equipment I have.? As I
said, I have an 9000/300 system and a good hpib analyzer to work with.
I'd be interested in any insight you have developed in the process of
translating the software.? I'd be willing to share any of the HP softwar
I've collected ? On that note, I have calibration and verification software for many,
many different instruments that I got from a calibration house that shut
down.? It will be awhile before I will be able to image the disks and
tapes, but that is my eventual plan.? They are safe for now.
????????????? -Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: Racks for older equipment
Costco also sells them. Bakers Racks. I bought a dozen of them a
couple of years ago to set up gear in my garage. They were 79.00 on
sale. I did find that a dozen of these is about the limit for a Chevy
S10 longbed pickup.
Sam Reaves
ARS W3OHM
Owner and Moderator of:
LeCroy Owners Group on Groups.io (Current and Future Group)
Electronics and Mechanical Hardware Design Engineering Manager
Andritz Rolls Global Research Center (RETIRED)
|
Re: Seeking advice on a precision DVM
FWIW I have a Fluke 8842A. It reads down to .001 ohms. 5v on the probe tips.
|
Hello,
I have a friend that is looking for the schematics of the power supply of its HP70004 in high quality. He has some files but they are not readable.
Someone could help us to find that document ?
Thank you,
Best regards,
Fabien, F4CTZ.
|
Re: Racks for older equipment
LOL at the Jean Stapleton (AKA Edith Bunker) "Those Were the Daaaaays" memories!
Jim Ford?
Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message -------- From: Dave McGuire <mcguire@...> Date: 4/10/20 7:47 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] Racks for older equipment
On 4/10/20 10:43 PM, bownes wrote: > When working for a small CLEC that became a good sized one (where I > became acquainted with the good Dave McGuire) we used to put a microwave > data endpoint, a T1 modem, a router and a switch in a rock n roll road > case and ship it to places we wanted to do temporary internet drops. It > survived a few years including a trip to Woodstock 25th reunion.? ? <Jean Stapleton voice> ? Those were the days! ? </Jean Stapleton voice> ?????? -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: Seeking advice on a precision DVM
On 2020-04-10, at 22:05, victor smith <vcs3@...> wrote:
And actually price/performance might lead you to the hp 3457, they are ridiculously cheap.
(Full disclosure: I just got three more :-) But they are full rack size units, like the 3456 also. And bench space is important, to me! Well, the 3457A are rack width (425mm (16.75 ¡°)), but only 292mm (11.5 ¡°) deep (compare to 3456A at 527.1 mm (20? triple-barleycorns)). Compared to a 3456A (10.49 kg (23.13 lbs)), they are also very light (5.05 kg (11.1 lbs)), so they can be lugged easily to the place they are needed. The robust plastic case and the low weight also mean that it¡¯s a bit harder to damage them while lugging them around. Disadvantage: the 3457A input resistance is 10G¦¸ only up to 3 volts, while the 3456a can do 12 volts at that input resistance. But then, in Ohms, 10 ?¦¸ resolution, where the 3456A is 100 ?¦¸. The 3457A can output up to 12 V in Ohms ranges, enough to fry many MOSFETs (so hello Harbor Freight(*) for that!), while the 3456A is slightly friendlier to your circuits at 9.5 V max. And so on. And don¡¯t forget the 3457A are 3030000 counts [6.48 digits], so they have more than one bit more of resolution than the 1200000 counts [6.08 digits] of the 3456a. I still love the 3456A display, though¡ Only the Keithley 192/196 are even more beautiful. [Well, OK, Datron 10xx can¡¯t be beat, but those are not LED.] Gr¨¹?e, Carsten (*) OK, ANENG. And those are incredibly accurate for what they are¡
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Re: Seeking advice on a precision DVM
I have 2 HP3456's, picked up in the San Diego area for $20 and for $50. I like the fact that it is calibrated with multi-turn pots accessible from the front panel, rather than calibration constants stored in a battery backed up memory. Long out of cal and my DIY LM399 10 Volt source also long out, but checked recently against an average of 3 out of cal meters, so I'm eagerly waiting my turn for access the the EEV floating cal standard.
<>
Hope COVID19 doesn't break the chain.
I've bought a pair of Aneng AN870 4 1/2 handheld multimeters and found them to be within spec, much better than a Harbor Freight meter.
David, contact me privately and perhaps I can get some 0.01% resistors to you to check your ohmmeter. KK6IL@...
John
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On 4/9/2020 10:28 AM, Daniel Koller via groups.io wrote: Hi All,
? I am wondering what sort of DVM the collective wisdom here might suggest for precision work.
? I am working on a project for work that involves designing a precision voltage controlled current source.? But due to the current pandemic, I am working from home and assembling and testing stuff in my own well equipped basement shop.? ?The current source is more or less a design out of Horowitz and Hill's "The Art of Electronics".? ?I am working to keep the full scale and linearity of this current source to within 0.1% or better.
? My current best DVM is a Keithley model 173 DMM "4 and 1/2" digit, 4-wire meter (the leading digit reads to 3).? It's accurate to ~0.009%+1 digit over 24 hours on the V scales and ~0.035%+1 digit on the Ohms scales.? ?I think it's good enough for what I need, but it has a few limitations, and I am wondering if it is not time to upgrade to a real bench instrument.
? ?First of all, my DVM probably hasn't been calibrated in decades.
?How do I know it's correct without some externally calibrated transfer standard?? ?It *may* be a possibility for me to use a meter at work (sent regularly to calibration services) and calibrate a portable voltage reference and bring it home.? ?But I don't have a resistance standard.
? The other problem is that even with 4 wires on the lowest Ohms setting, I don't have enough resolution to measure a 0.100 Ohm sense resistor to within 1%.
? ?So, I think I could use a better meter.? ?The HP34401A DVM seems like a nice meter to have.? It's even used as a circuit design example in H&H's text.? But they seem to go for several hundreds of $$ on e-bay.? ?Remember, this is coming out of my hobby budget.
? So, I looked at the? HP3455A / 3456A on e-bay.? These seem to be significantly cheaper, and I love vintage instruments.? BUT, do I want to take up a new project?? How reliable are these old beasts?? Are they easy to repair and calibrate?? ?What tends to go wrong with them?
? ?Even though it's more expensive, one major strong point of the HP34401A is in addition to GPIB, it's got a SERIAL interface on the back!? That is a whole different ballgame in terms of interfacing to a PC or laptop (and a whole lot easier for me, for sure).? But I do think I want to have a meter I can use, rather than one I will have to repair.
? Are there any other models I am missing?? ?Are there any that come standard with an RS232 interface?? Please let me know and thank you in advance for your suggestions.
? Dan
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Re: Craigslist HP 8566B Indianapolis
On 4/10/20 6:48 PM, wallydoc via groups.io wrote: To Dave M, re: Marconi 2380
I have almost all HP equipment also.
I received a great deal of help from some guys on the Marconi Groups io
when I needed advice on repairing mine. I think at least two of them
seemed to have worked for Marconi and seemed extremely knowledgeable
about the unit. I do not think I have ever received more expert advice,
if you have problems with your Marconi, I would recommend joining the group.
I changed the input on mine from 75 ohms to 50 ohms. Then had a problem
with the keypad "bouncing" e.g. putting up 22 when I just hit 2 once. If
that is your problem, I have all my notes. Also the thread was
relatively recent and should be easily found.? Hmm, that is very encouraging. I had put the 2380+2382 into storage when I needed to clear up some workspace; perhaps it's time to pull it out and get it on the bench. I shall look for that Marconi group. But no, the problem is general flakiness and random behavior, not switch bounce. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
|
Re: Seeking advice on a precision DVM
For a great many measurements that most of us make, I suspect the the "free" Harbor Freight Tools DMM serves the purpose just fine. It's great for quick checks and especially continuity testing.?
You probably don't need to fire up your 6 1/2 digit "wonder meter" to measure a nine volt battery or to confirm that a five volt bus in an instrument is still working. Each instrument has it's place.
Stuart K6YAZ
Los Angeles, USA?
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Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
The manual nulling was much faster and it didn't take long to get the knack of it!
No problem. I only remembered it because I have two 331A too repair and they are in the same family. The 333A/334A have the auto nulling, where the 331A/332A don't. I've used a 334A in production test, but I could get a manual null faster on a 331A. All four versions are nice Distortion analyzers.
On Wed, Apr 8, 2020 at 8:11 AM Chuck Harris < cfharris@...> wrote: I'm sorry Michael, I misremembered.? Before I looked in the
manual, I remembered lamps, of some sort, and CdS photoresistors,
and it registered as a choppers.
It is actually a Wien Bridge.? Three of the four legs are CdS
photoresistors.? One lamp feeds two of the photoresistors, and
the other feeds a single photoresistor.
The last time I worked on 334's was about 1984.? I am surprised that
I remembered as much as I do.
-Chuck Harris
Michael A. Terrell wrote:
> The 334 has an Automatic Nulling (A6 board) circuit which uses lamps and a
> single detector. I see no chopper.
>
> On Tue, Apr 7, 2020 at 12:04 PM Jeremy Nichols <jn6wfo@...> wrote:
>
>> Purely out of curiosity, what is the purpose of a chopper in a 334
>> distortion analyzer? HP used choppers in a lot of their DC voltmeters to
>> convert the DC to AC. They¡¯d run the AC through some amplifiers and then
>> convert back to DC to run the meter. That took care of the old DC amplifier
>> drift problems. Since a distortion analyzer is already working with AC, I
>> would think a chopper wouldn¡¯t be necessary. Obviously there¡¯s something
>> I¡¯m missing.
>>
>> Jeremy
>>
>> --
>> Jeremy Nichols
|
Re: Racks for older equipment
On 4/10/20 10:43 PM, bownes wrote: When working for a small CLEC that became a good sized one (where I
became acquainted with the good Dave McGuire) we used to put a microwave
data endpoint, a T1 modem, a router and a switch in a rock n roll road
case and ship it to places we wanted to do temporary internet drops. It
survived a few years including a trip to Woodstock 25th reunion.? <Jean Stapleton voice> Those were the days! </Jean Stapleton voice> -Dave -- Dave McGuire, AK4HZ New Kensington, PA
|
Re: Racks for older equipment
When working for a small CLEC that became a good sized one (where I became acquainted with the good Dave McGuire) we used to put a microwave data endpoint, a T1 modem, a router and a switch in a rock n roll road case and ship it to places we wanted to do temporary internet drops. It survived a few years including a trip to Woodstock 25th reunion.?
Bob
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On Apr 10, 2020, at 22:17, Matt Patoray <mspproductions@...> wrote:
?
On Fri, Apr 10, 2020 at 6:47 PM Dave McGuire < mcguire@...> wrote: On 4/10/20 6:28 PM, Jim Ford wrote:
> I'd be concerned about the weight.? Audio gear tends to be a lot lighter
> than microwave gear.? They were throwing away some 19 inch server racks
> at work a month ago or so, and I would have grabbed one, but I figured
> it wouldn't hold the weight of my stuff.? Be careful and stay safe, both
> physically and biologically.?
? Hmm, methinks you've never had to move a few kW worth of stage
amplifiers. ;)
? ? ? ? ? ? -Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
? Been there done that, it is surprising?what you can throw into an SKB road case with no issues. I used to limit our 8U SKB cases that we used for amps to about 110 pounds, so they could still be moved but run a small stereo setup with mains and a sub, normally 2 Mackie M-1400's and the Behringer equivalent of a DBX? drive rack,? or the QSC equivalents and the Behringer clones of the QSC. The other 8U road cases where not as heavy as they just contained a pair of Tascam DA38 multitracks. --?
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Re: Racks for older equipment
On Fri, Apr 10, 2020 at 6:47 PM Dave McGuire < mcguire@...> wrote: On 4/10/20 6:28 PM, Jim Ford wrote:
> I'd be concerned about the weight.? Audio gear tends to be a lot lighter
> than microwave gear.? They were throwing away some 19 inch server racks
> at work a month ago or so, and I would have grabbed one, but I figured
> it wouldn't hold the weight of my stuff.? Be careful and stay safe, both
> physically and biologically.?
? Hmm, methinks you've never had to move a few kW worth of stage
amplifiers. ;)
? ? ? ? ? ? -Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
? Been there done that, it is surprising?what you can throw into an SKB road case with no issues. I used to limit our 8U SKB cases that we used for amps to about 110 pounds, so they could still be moved but run a small stereo setup with mains and a sub, normally 2 Mackie M-1400's and the Behringer equivalent of a DBX? drive rack,? or the QSC equivalents and the Behringer clones of the QSC. The other 8U road cases where not as heavy as they just contained a pair of Tascam DA38 multitracks. --?
|
Re: Racks for older equipment
Yeah... I looked it up.?? I was finally able to actually see the
photo, but it was a frustrating experience.?? There was also
supposed to be some conversion tools, but all the ones I found took
you to the Microsoft store to sell it to you.?? I didn't find it to
be worth my while.? I saw enough..
Daun
On 4/10/2020 8:59 PM, Michael A.
Terrell wrote:
HEIC is an Iphone filetype. Microsoft is supposed to have a
free codec for Windows, but I couldn't get the link to work.
On Fri, Apr 10, 2020 at 12:46
PM Daun Yeagley < daun@...> wrote:
What is a ".HEIC" file?? I can't open it.
Daun
Daun E. Yeagley II, N8ASB
On 4/10/2020 12:05 PM, bownes wrote:
The other thing
that works well is the wire rack rolling carts. They
will hold a lot of weight and an outlet strip fits
well behind the handle. I keep the gear on a set of
wire rack shelves, roll the cart over, pull off what I
need for a given exercise, roll the cart back to the
bench, and off I go.
On Fri, Apr 10, 2020
at 9:08 AM ArtekManuals < manuals@...>
wrote:
Wally
Depends on largely on
1) The size of the castors ( wheels), bigger wheels
are generally easier
to deal with and actually less likely catch and tip
2) The floor surface they are rolling on
Weight? can be a factor, put? heavier on the bottom
-Lighter on the top
) think low center of gravity
Though things have changed in my current set up and I
have long since
abandoned the racks, you used to be able to find racks
that were 36"?
high. I really like these if you have the room as the
make great rolling
"table tops" with a power supply in the bottom
Dave
NR1DX
On 4/10/2020 7:09 AM, wallydoc via
wrote:
> I have a bunch of old HP and other equipment and
am using a Tek scope
> stand for some of it. I was wondering if anyone
had any suggestions
> about rolling stands for TE, Do the rolling
racks?that musicians use
> for their audio equipment work well enough? They
are 19 inch racks.
> Any suggestions would be helpful.
>
> Wally KC9INK
>
--
Dave
Manuals@...
--
This email has been checked for viruses by Avast
antivirus software.
--
Daun E. Yeagley II, N8ASB
|
Re: OT: Help identifying these mixers required - ADTEC
?
I have
Skolnik's
first edition
RADAR Handbook. His name was also used in the "Revenge of the Nerds' movie.
Tim,
The other device was made by ADTECH as you noted, later ECI, which was bought by Alpha Microwave (when Control Data owned them) and became the basis for their MMW mixer line. My first boss at Westinghouse Defense was one of the principles at ADTEC (all came from Johns Hopkins, including Merrill Skolnik and other notables). Really innovative MMW company in the early 60's.
IIRC, uses a MMW flat cartridge crystal, point contact type with a hand pointed Tungsten whisker (using HF) made by Frank Trageser (only guy who could do them right...).
If the diode tests good with a ohm-meter for some sort of front to back ratio then you are in business. Use typical precautions.? Mostly used in the harmonic mode with LO & IF diplexed together on the N connector, IF in the DC-several GHz (10 ?) range. If both ends open, you can use in fundamental mode mixing. NF ranged in the 15-20 dB area.
Should get you close.
BTW, if you decide to get rid of the ADTEC device, let me know, would like it for the collection.
Regards,
Jeff Kruth
In a message dated 4/7/2020 10:07:18 AM Eastern Standard Time, Brucekareen= [email protected] writes:
Tim,
Demornai-Bonardi 633 devices were directional couplers that coupled to a crystal detector on one coupled side and a flange on the other.? They were generally used with a reflecting cavity wavemeter on the flanged port to measure frequency.? The W version would have covered 90 to 140 GHz (WR-8).? These are fairly early designs and yours is probably at least fifty years old.? I am not familiar with the other device.
Bruce, KG6OJI
|
Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
No problem. I only remembered it because I have two 331A too repair and they are in the same family. The 333A/334A have the auto nulling, where the 331A/332A don't. I've used a 334A in production test, but I could get a manual null faster on a 331A. All four versions are nice Distortion analyzers.
On Wed, Apr 8, 2020 at 8:11 AM Chuck Harris < cfharris@...> wrote: I'm sorry Michael, I misremembered.? Before I looked in the
manual, I remembered lamps, of some sort, and CdS photoresistors,
and it registered as a choppers.
It is actually a Wien Bridge.? Three of the four legs are CdS
photoresistors.? One lamp feeds two of the photoresistors, and
the other feeds a single photoresistor.
The last time I worked on 334's was about 1984.? I am surprised that
I remembered as much as I do.
-Chuck Harris
Michael A. Terrell wrote:
> The 334 has an Automatic Nulling (A6 board) circuit which uses lamps and a
> single detector. I see no chopper.
>
> On Tue, Apr 7, 2020 at 12:04 PM Jeremy Nichols <jn6wfo@...> wrote:
>
>> Purely out of curiosity, what is the purpose of a chopper in a 334
>> distortion analyzer? HP used choppers in a lot of their DC voltmeters to
>> convert the DC to AC. They¡¯d run the AC through some amplifiers and then
>> convert back to DC to run the meter. That took care of the old DC amplifier
>> drift problems. Since a distortion analyzer is already working with AC, I
>> would think a chopper wouldn¡¯t be necessary. Obviously there¡¯s something
>> I¡¯m missing.
>>
>> Jeremy
>>
>> --
>> Jeremy Nichols
|
Hmmm.. 250 to 800 MHz sounds pretty wide for a suckout. Too bad the OP can't go beyond 1 GHz to check for periodicity.
Daniel, I have a 5343A and can test up to 20 GHz. IFAIK, mine is working perfectly. Let me know if you want me to check signals at any point.
Jim Ford
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Show quoted text
------ Original Message ------ From: "Dave McGuire" <mcguire@...> To: [email protected]Sent: 4/10/2020 11:43:56 AM Subject: Re: [HP-Agilent-Keysight-equipment] 5343A troubles On 4/10/20 1:48 PM, Daniel Sheen wrote:
I have a rather bizarre problem with a 5343A counter. Observed symptoms
are that the high frequency input works reliably up to about 250MHz,
reads garbage from around 250MHz-800MHz, and then seems to work fine
from 800MHz upward through 1GHz (I only have an 8640B handy atm so can't
really test higher than that). Cranking up the input power a bunch seems
to reduce the dead band to closer to 400MHz-600MHz.
The counter initially failed troubleshooting step 4 in the service
manual. That was resolved by replacing the A10 board (from another
counter with a blown sampler). It now passes step 5 and is marginal on
step 6 (sensitivity is a little lower than it ought to be but it seems
to work).
The one other observation I've made is the IF amplitude into and out of
A11 drops off rapidly if an input is tuned into the range of frequencies
that it's insensitive to, but I'm struggling to find a plausible
explanation for why that could occur given my understanding of the
counter design (that wouldn't also make higher frequencies not be detected).
If anyone has any thoughts or has run into this before, suggestions
would be appreciated. That almost sounds like the "suck-outs" that are typical of a damaged
or loose hardline cable. I would check the input connectors and, if
there's the standard SMA-terminated 0.141" hardline on the inside, look
for hairline cracks around the solder joints around the connectors, or
similar damage.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: Seeking advice on a precision DVM
Ha!? I love my freebie Harbor Freight DMM!? Nice feature is the On/Off switch; why do I have to turn the darn dial back to Off every time, when 99 times out of 100 I'm just going back to Ohms anyway?!? Some of my other DMMs don't have that nice feature.
I'm considering getting a couple of 34401A's since I've used them before at work, they are nice instruments, and they are all over the place.? I remember using the high impedance ohms mode when working down in the nanoamp range and getting weird results with a "normal" handheld DMM.? It didn't take me long to figure out the bias and offset currents of the normal DMM were higher than what I was trying to measure.
I figure one 34401A for a dedicated connection to my 432A microwave power meter bridge circuit, GPIB to the computer, and let it calculate the RF power.? Another 34401A for general bench use.? Last time I checked the 'bay, there were seventy 34401A's for sale!
Jim Ford
------ Original Message ------
Sent: 4/9/2020 3:24:06 PM
Subject: Re: [HP-Agilent-Keysight-equipment] Seeking advice on a precision DVM
I'd vote for the HP3455A and HP3456A. I have about three of each, and I did have to repair some of them initially (which is why they were quite cheap) - mostly the usual bad power supply cap replacement. I prefer the 3455A user interface, even though the 3456A is supposedly a little newer and better.
If you're moving from 4.5 to 6.5 digits, it will be like a breath of fresh air. You? may be able to just not worry about calibration yet, since even if old, they will likely still be much better than your old gear. During a design, you can probably get by with less than ideal equipment, and no standards to compare. For the time being, it appears you mostly need more resolution, not necessarily absolute accuracy. As you get to the end, then you can worry about the exactness.
BTW I have one old DMM that's very cool, I think, because of its exceptional resistance measurement capability. It's a DANA 5900, which at first glance is just another old 1970s lab grade DMM, with 5 digits plus 60% over-range. What's cool is that it utilizes those digits well - it includes 100 meg and 10 ohm FS ranges, which are outside those of typical DMMs. Indeed, they're out of its own auto-ranging capability, and have to be selected manually. At the high end, it tops out at 160 megs with 1 k ohm resolution. At the bottom, it can read to 16 ohms with 100 micro-ohm resolution.
I picked this up years ago at a flea market for somewhere around free to five bucks, as I recall, and it worked when I checked it out. I was considering junking it out, since it's old and beat up, and I have plenty of DMMs, until I discovered the ohms ranges. I saved it set it aside just for high megohm use. I recently had need to use it, and found it had crapped out. I've been working on it on and off over the last couple of months, trying to save it. It's almost OK now. If not for those ohms, it would be long gone.
This goes to show that even if you have good, working stuff, it can still let you down, resulting in repair or replacement projects. This will of course tend happen when you need it the most.
Anyway, I'd recommend not looking for "a" new DMM, but "some" new DMMs, if it's for a mission-critical need. I keep the HPs on the shelf in reserve or for high grade measurements, my bench DMMs are old Fluke 8400As (5+ digits), but mostly I use my pile of Harbor Freight freebie DMMs.
Ed
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Dave McGuire
Sam Reaves
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Michael A. Terrell