Re: HP34702A Ohms converter issues
"Hewlett Packard Interface Loop".? It was a very low power serial
interface that formed a loop (all devices in a circular loop).? It
was designed for use with battery operated (i.e. low power) devices
and controllers such as the HP-41 calculator or HP-71 handheld basic
computer.? It was handy for data acquisition in vehicles.
Daun
Daun E. Yeagley II, N8ASB
On 2/15/2019 10:23 AM, Steve Hendrix
wrote:
toggle quoted message
Show quoted text
At 2019-02-15 10:06 AM, Jeff Anderson wrote:
Unfortunately, the
3468B
instruments have HP-IL ports in lieu of HP-IB.
What is HP-IL?
|
Re: HP34702A Ohms converter issues
At 2019-02-15 10:06 AM, Jeff Anderson wrote:
Unfortunately, the 3468B
instruments have HP-IL ports in lieu of HP-IB.
What is HP-IL?
|
Re: HP34702A Ohms converter issues
Jeff,
The lithium cells hold voltage up to end of life and then die not gradual.? If you are clever, you can parallel another battery clipped into the circuit to hold the voltage and cal constants while you unsolder and replace the battery under the shield.
George
|
Re: HP34702A Ohms converter issues
These look like excellent buys and will take offers:
Not sure I believe the statement about the camera flash washing out the display -? seems like some segments might be missing? -? would want that verified first
|
Re: HP34702A Ohms converter issues
The CAL? RAM? battery may have also failed.? It is under the analog shield and is a 3v Lithium cell that is used in many instruments.? I would replace it out of general principles for we never dreamed the instrument would still be in use 38 years later from first release.??
This last year I checked the RAM-backup batteries on my two 3468B and two 3478A multi-meters.? All were at about 3.03 volts.? Never the less, I and Dick Benson, W1QG, wrote MATLAB scripts to let us read and write cal data from and to our 3478A instruments via the their HP-IB ports, "just in case". Unfortunately, the 3468B instruments have HP-IL ports in lieu of HP-IB.? I haven't figured out what to do for these two instruments.? Maybe replacing the batteries is the way to go.? But it would be nice to be able to back up their data, too. Any idea what the discharge characteristics of the Lithium batteries used in these instruments is?? Is it gradual?? Or is it 3.03 volts one day, 0 volts the next? Thanks! - Jeff
|
Re: HP34702A Ohms converter issues
There are several 3478A meters for sale on EBAY for under $100 including shipping.? It always pays to make an offer even when that option is not stated.? ?The 3478A is identical to the 3468A/B in the basic operation and specs.? The two instruments were co-developed using the same analog circuity I designed.? ?The differences are:
3468A? ?HPIL interface (controlled by HP41C handheld calculator),? ? Has battery power option?
? ? ? ? ? ? ? Packaged in plastic clam shell case with movable carrying handle? -? designed for portable field operation with battery
? ? ? ? ? ? ? No front rear switch - no rear terminals
3468B? ?HPIL interface (controlled by HP41C handheld calculator),? ? Has battery power option?
? ? ? ? ? ? ? ?Packaged in plastic rack and stack case with NO carrying handle??
? ? ? ? ? ? ? No front rear switch - no rear terminals
3478A? ? ?HPIB interface (IEE488? bus),? ? NO battery power option?
? ? ? ? ? ? ? ?Packaged in METAL rack and stack case with NO carrying handle
? ? ? ? ? ? ? ?Rear terminals with front/rear switch
For bench work where you might want bus operation / programming? the 3478A is what you want for the HPIL (Hewlett Packard Instrument Loop) never caught on and was only available on certain handheld calculators(HP41C, HP75) and the desktop controllers (HP85, 86 with HPIL interface cards)
The 3478A is just as easy to work on as the 3468 for it also is just a single motherboard and was designed using same philosophy as the 3468.? There only differences are primarily in the packaging and I/O interface ( HPIB? vs HPIL)
Display repair is not difficult.? The LCD display is the same as used on the 3488A ( another project I was the analog engineer on -? designed all the 4447X I/O interface cards)? -? ?There are so many 3488As mainframes in the field they are practically being given away today in the used market.? 100s of thousands were sold? ?Very successful and popular product used in manufacturing test.
George
|
Thanks, Leo.
DC Volts works fine.? But to quote the 3478A manual troubleshooting section (section 7-A-31, DC Current Troubleshooting):
"If the DC Volts Function is good, the only components that can cause a current failure are an open current fuse (F101), a defective resistor R107, or the Input Hybrid U102."??(The manual also notes that the A/D controller (U462) could be the issue -- but given that all other functions work, and that its interface to the hybrid looks to be serial, it is low on my very short list of suspects).
I haven't looked at the meter for about a year (and it's at a different location at the moment and thus inaccessible until I return from vacation), but I believe I verified the fuse and the resistor were OK, leaving the hybrid (and/or its control) as the possible culprits.? I'll look at it again when I return.
- Jeff
|
Re: Looking for silicone HV potting goop
When I have a very small amount of potting to do, I
use Permatex silicone windshield sealant. It is a clear,
1 part RTV that is not acid cure (though there was a time
when it was, so use your nose). It pours like maple
syrup, and cures quickly. I would not do it for something
that was totally in a cavity (test tube), but for something
that is in a shallow and wide pan, it is great.
For HV, you must be certain it is fully cured before applying
power.
-Chuck Harris
Dave_G0WBX via Groups.Io wrote:
toggle quoted message
Show quoted text
You got there before me. "Dow Corning Sylguard" But I forget the
actual product number, there are several variants. "Water clear
silicone two part rubber compound". The annoying thing was you had to
measure it out by weight, not volume, and ideally, use a vacuum system
to get all the air out once you'd pored it into the assembly.
Take care, there is a use by date, not a problem going over a few
months, but years over, and it may not cure correctly, or will cure too
fast, so you get trapped air bubbles in annoying places..
ST Keltec used to (maybe still does) use the stuff for their TWTA HV
PSU's. And I too sometimes buried "diagnostic" LED's inside modules I
repaired! Always good to know the Filament was actually powered, at
the very least.
Regards.
Dave B. (Member of the UK co' who used to Rep' Keltec some 20 years
ago!) No, we don't repair them any more.
PS: Throwing chunks of it onto a hard floor, would make cat's go
potty chasing it...
|
Re: Looking for silicone HV potting goop
You got there before me.?? "Dow Corning Sylguard"? But I forget the
actual product number, there are several variants.? "Water clear
silicone two part rubber compound".? The annoying thing was you had to
measure it out by weight, not volume, and ideally, use a vacuum system
to get all the air out once you'd pored it into the assembly.
Take care, there is a use by date, not a problem going over a few
months, but years over, and it may not cure correctly, or will cure too
fast, so you get trapped air bubbles in annoying places..
ST Keltec used to (maybe still does) use the stuff for their TWTA HV
PSU's.? And I too sometimes buried "diagnostic" LED's inside modules I
repaired!?? Always good to know the Filament was actually powered, at
the very least.
Regards.
Dave B.? (Member of the UK co' who used to Rep' Keltec some 20 years
ago!)?? No, we don't repair them any more.
PS:??? Throwing chunks of it onto a hard floor, would make cat's go
potty chasing it...
--
Created on and sent from a Unix like PC running and using free and open source software.
::
|
G'day Colby, Can the Agilent ESG-D3000A be hacked to the E4437 standaed? I understood the ESG-D3000A was equilivant to the E4432 standard. Regards CRO-TEK Sydney, Australia
On Wed, Feb 13, 2019 at 1:53 PM Tom B < tbryan@...> wrote: Hi Tim,
Nice. Interesting that it is that accurate at 4GHz after the conversion.
I have more than several of these generators and I think they are great.
I noticed on mine that if you do a hard reset (I don't recommend that
unless you can't do anything else) that, regardless of model, that they
default to 4GHz until you go below the models frequency and then won't
go back up.
These are not high end generators but good enough and you can't beat the
price for what you get.
Tom
On 2/12/2019 1:11 AM, Tim Tuck wrote:
> Hi Tom,
>
> At 4GHz, using my E4406 to measure its output from -90dBm to +13dBm,
> it appears to be within 0.5dBm of indicated.
>
> Above 13dBm the power doesn't increase and the UNLEVELED indicator
> comes on at about 14dBm.
>
> Using my HP438A and HP8481H to do the same test gives a similar result
> but with an additional -1dB offset.
>
> So its "close" :) ... well at least at 4Ghz
>
> None of this kit has been calibrated in years so take the result with
> a grain of salt!
>
> Given a bit of time I could write a labview thing to make some nice
> measurements and plots some graphs
>
> regards
>
|
At 2019-02-15 05:18 AM, ea7hwx@... wrote:
What happens is that I already
have a GPIB to USB converter (I bought the prologix a long time
ago).
Maybe I have not explained myself correctly (sorry my English). I do not
send the display info to a plotter to print.
Your English is fine - much better than my Spanish!
I think my documentation needs work to fully explain how KISS-488 works
as a plotter. KISS-488 appears to the instrument to be an HP7470 on the
IEEE-488 bus. On the Ethernet side, you simply connect any browser, and
KISS-488 presents a picture just as the plotter would print it. From
there, you can do anything you could do with any image - cut-and-paste
into a document, save as a disk file, print it on any printer your
operating system knows about, etc. Truth be told, it was my main reason
for designing KISS-488, and my primary use for it.
But if you have already bought the Prologix unit, I understand you would
be reluctant to buy another. I bought one of those myself and found it to
be too difficult to use, so I resold it on eBay and designed
KISS-488.
Best of luck with your project!
Steve Hendrix
|
Re: HP34702A Ohms converter issues
Greg, Yes someone did grab the $75 one ;-) All this discussion made me want one. ?Don't know why but seemed like I needed one.? I will report back once it arrives. ?
Dave
toggle quoted message
Show quoted text
On Feb 14, 2019, at 10:35 PM, gregdunn@... wrote: Well, someone did grab that one - but I found another for just a little more, claimed to be working.? I guess I'll open a new thread for it when it arrives!
|
Hello Dan,
I have a copy of the HP8412A manual but unfortunately I only have the "Manual Change 1 and 2". Anyway the A3 card that I have doubts is 08412-60063 (HP8412B) and this is very different from the HP8412A (08412-60003).
In my manual the original HP8412B says that the A3 card has the code: 08412-60063 instead my display 8412B has an A3 card with code 08412-60047 ???
I have reviewed the scheme with 08412-60047 and at a glance the difference is that my card does not have the A3S1 (blanking polarity) switch. I have not kept looking for differences.
!What a mess!
If I can not find an explanation for the differences, I will continue trying to find the fault with the scheme of the A3 08412-60063, it is very similar.
Regarding interesting comment about the change in U1, U3 and U4.
1820-1941 cross reference LF13201N
1826-0582 cross reference LF13201D
I have already changed them but to new LF13201N, I do not have "D" version.
Certainly the analog switches usually give problems but in this case they do not seem to have a problem.
If it's not too much trouble, I'd like to have that copy of "manual changes" by email. I'm very grateful.
Rafael.
EA7HWX
Seville (Spain)
|
Hi Steve,
Of course and I appreciate your offer.
What happens is that I already have a GPIB to USB converter (I bought the prologix a long time ago).
Maybe I have not explained myself correctly (sorry my English). I do not send the display info to a plotter to print. The chain that I thought:
- VNA 8410C with HP8412B display. This HP8412B has the interconnect connector to Normalizer.
-HP8750A Storager Normalizer connected to the HP8412B display.
-The HP8750 has analog output X, Y, and PEN.
- The previous analog outputs will not connect to a recorder or plotter but will enter two of the channels of the digital oscilloscope HP5412B in X vs Y mode.
- The graphic representation of the scope if I can treat it on the PC thanks to the Prologix that I already have.
I have seen the specifications of Your USB - GPIB.
It looks good and very competitive price.
Thanks for the offer.
Rafael
|
Hello, Let me take this off-topic for a second. I am currently almost ready to move into my big ass underground lab. New air supply system so I never need to open a window again, fart and slinker - all is done. Sadly, all the air coming in, means humidity coming in too. I solved that problem by buying two dehumidifier machines - they cost like 120 Euros a pop, and will arrive on Monday or Tuesday. Maybe these can also be an option for you. Having to deflux kit would drive me mad. Tam
With best regards Tam HANNA (emailing on a BlackBerry PRIV) Enjoy electronics? Join 14k other followers by visiting the Crazy Electronics Lab at Am 15. Februar 2019 02:58:38 MEZ schrieb "Reginald Beardsley via Groups.Io" <pulaskite@...>:
toggle quoted message
Show quoted text
I just got my 2nd 3478A. I already have two 34401As. The 3478As are for monitoring currents on bench PSU outputs.
My first 34401A arrived completely wonky. Every mode was random digits. When I opened it up I found a 1 cm brown flux stain around an LF378 which had been replaced. Not quite lined up and different make.
So I took a bottle of 91% isopropyl and a soft brush and cleaned the board. It has worked perfectly ever since and is within a few ppm of my other 34401A and my DMMCheck Plus and 10 V references from Doug Malone.
I tumbled to the issue living in Houston when two VCRs each died after a year of *very* light use. I opened them up to look for parts to scavenge before trashing them and observed that they were covered with flux residue. Rosin flux is hygroscopic and absorbs moisture out of the air. With the shift from 5 V to 3.3 V and lower logic levels, noise margins have gotten rather narrow. And Houston is not hot so much as it is humid. I had to squeegee dew off my windows every morning before driving to work.
I've now made 7-8 repairs which consisted of nothing other than cleaning flux residue off a board. The most recent was a cheap motion sensitive LED night light. I'd taken it apart to scavenge the battery holder when I noticed a small area of flux residue. Out of curiosity I cleaned it and reassembled it which was a good bit of work as I'd already pretty much disconnected everything except the PCB components and every time i resoldered a wire the other end would break off. It now works flawlessly and has for several months.
The issue is so common that I plan to build an IPA pressure washer using an electric fuel pump with a distillation system to repurify the IPA. In the last 10 years it has been the most common failure mode I have encountered.
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#94384): /g/HP-Agilent-Keysight-equipment/message/94384
Mute This Topic: /mt/29846878/102401
Group Owner: [email protected]
Unsubscribe: /g/HP-Agilent-Keysight-equipment/leave/defanged [tamhan@...]
|
Re: HP34702A Ohms converter issues
Well, someone did grab that one - but I found another for just a little more, claimed to be working.? I guess I'll open a new thread for it when it arrives!
|
Re: Looking for silicone HV potting goop
Dow SYLGARD? 184 Silicone Encapsulant Clear 0.5 kg Kit
|
Re: HP34702A Ohms converter issues
Greg,
The error 15 could be a RAM failure.? The Mostek part had a metal migration problem that was not discovered until late into the production.? The CAL? RAM? battery may have also failed.? It is under the analog shield and is a 3v Lithium cell that is used in many instruments.? I would replace it out of general principles for we never dreamed the instrument would still be in use 38 years later from first release.? ?Lithium cells are readily available at battery stores.? I just purchased a pack of 8 with 10 year life rating for $15.? You can tack on leads with a large soldering iron that has high heat so can do it fast or spot weld with a capacitor discharge.
This instrument was designed for serviceability and is very easy to disassemble and work on.? Everything is on one PCB.? If you work on the instrument, cleanliness is important.? The PCB has a special coating on it called PPC giving it the greenish tint that was especially developed for this product and used in subsequent instruments.? The very high impedance nature of the coating eliminated the need for teflon standoffs in low leakage high impedance nodes -? very important for reducing manufacturing labor costs.? You will find extensive use of teflon standoffs in the 3455 and 3456 meters which were introduced before the development of this special PPC coating.? This coating maintains a surface impedance on the order of 10^13- 10^15 ohms per square.? It was quite a innovation break thru for DMM development.? Actually, many new development innovations were implemented on this project.
You should have enjoyment on your purchase of the 3468A
George
|
Re: Looking for silicone HV potting goop
Are you familiar with General Cement's High Voltage Putty? It was used in the HV circuits on TVs for decades to prevent corona leaks and arcing.? I saved a lot of flybacks and some CRTs with it. It? doesn't harden, so you can remove it for repairs and reuse most or all of it. It is translucent, so you should still be ale to see that LED.
Here is the first listing I found:
https://www.verical.com/pd/gc-electronics-unsorted-10-8880-1040080#specs -----Original Message-----
From: "Ed Breya via Groups.Io"
I've been designing up some HV testing circuits, and plan to pot the parts that run up to 30 kV. I'm reusing a couple of plastic HV CRT supply boxes salvaged from old HP scopes, such as the 180. The anode multiplier section in these were potted with a beautiful clear silicone goop that was easy to remove, and in like-new condition after fifty years. I'd like to find the same kind of stuff for this new use. Does anyone know exactly what HP used for these back then?
I definitely want clear silicone, electrical/HV grade. I want it clear because I like being able to see into the guts during potting and operation, and I may have an LED buried inside to indicate current flow. I want it silicone so it can be torn out easily for design modifications - and clearness helps a lot with this.
Online searching seems to indicate RTV-11 is probably about right, if it's available in clear. Any other ideas? I see that the RTVs are pretty spendy nowadays, so I'm looking for reasonable prices on small quantity units, say around 250 ml. The volume to be filled is about 5-6 in^3.
PS: An interesting thing I noticed in searching, was some talk about making cheap (and sort of clear) electrical potting compound by mixing hot melt glue sticks into molten parrafin. Has anyone heard of this, or know more info? Something like this may be OK if it's fairly clear or translucent, and can be blended to be pliable enough for easy removal. Flammability isn't an issue here, since the power levels are low, and it's only for temporary testing hookups.
Ed
|
Re: Looking for silicone HV potting goop
Look into Dow Sylgaurd 170.
-- Sam Reaves
ARS W3OHM
Owner and Moderator of: LeCroy Owners Group on Groups.io (Current and Future Group)
LeCroy_Owners_Group on Yahoo! Groups (Legacy Group)
|
Michael A. Terrell
Sam Reaves