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Looking for manuals for Yokogawa-HP 4255A Universal Bridge

 

Hi all,
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I am thinking of maybe picking up a 4255A Universal Bridge for some fun, but I can't seem to find a manual for it anywhere.
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Does anyone have a copy of any user or service manuals for this instrument?
I'm happy to buy a paper manual (which I'll scan and upload) or if anyone has a scan they can provide?
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Thanks!
Jared
Re: YIG Oscillator Info?

 

Re YIG module power supplies.

Many (most?) "Modern" YIG modules likely protect themselves (but you'd be wise to assume they do not) from incorrect power sequencing.? However...

From personal hard won expensive experience, older units (from the 70's and 80's) are likely to NOT have any such protection built in.

The ONLY way to be sure is to find either the makers data sheet, or consult the detailed schematics of whatever instrument/assembly they were used in, to see how that handles the power distribution and how multiple rails come up from cold.

(One regulator has the voltage reference, other regulators use that output, and/or other regulator outputs as their reference, or enable/disable signals.? Sometimes it is less than obvious.)

The same applies to many modern microwave RF Gain Blocks, that use exotic FET devices.? They too can be instantly destroyed by sequencing the power rails the wrong way...? Again, do not "assume" they have built in protection, unless the makers data sheet says they have.? Even then, that may only protect it when the power is coming up, not if a bias supply fails while in use.

Oh, and yes, "Fine Tune" coils are very fragile.? The YIG may still oscillate if you burn that coil, but if that results in shorted turns, as it might, then the main coil tuning ability, regarding sweep speed will be seriously compromised, or even cause trouble in the main coil driver (over current issues) much as a shorted turn in a power transformer secondary can render it useless.

Take care, and never assume anything, in regards to salvaged RF assemblies of any sort.?? At best, nothing bad happens, but it doesnt work.?? At worst, "Phht"!?? And then more $$$$'s needed.

Regards to All.

Dave 'KBV.

--
Created on and sent from a Unix like PC running and using open source software:
Re: how to convert HP83711B to 83712B!

 

The 83711A/B was introduced in the early 1990’s or late 1980’s. The Spectrum Analyzer Division (Santa Rosa, CA) had converted the production line to run on 9000/382’s by that time. I would assume that the Network Analyzer/Sweeper Division had also done the same thing by that date.

Don Bitters
Re: HP 478A Thermistor Sensor. Input return loss and matching

 

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Yes, 1206 is rather large. ?I’ve not opened up the 478A or the other thermistor sensor I have for use with the 432A, one goes to 10GHz and the other to 18 GHz, but I would check into smaller resistors. ?0805, 0603, 0402, 0201, and the near-microscopic 01005 are common. ?I think they even go smaller than 01005. ?Conventional wisdom says smaller ones have lower parasitics. ?Good luck. ?HTH.

Jim Ford
Laguna Hills, California, USA?


On May 19, 2025, at 3:19?PM, jmr via groups.io <jmrhzu@...> wrote:

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Sorry, I made a typo the graph title should say inductance in nanohenries (nH) not uH. The measured Ls for the 1206 capacitor is 1 nH.
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Here's a simulation for the VSWR if the thermistors are not tracking perfectly. This is the case for when one thermistor is 90R and the other is 110R.
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Whilst this still looks really good, the VSWR rapidly degrades to 1.04:1 at 50 MHz if the thermistor tracking degrades to 80R + 120R. I've not show this case as it is probably unlikely to happen unless the sensor has been stressed at some point.
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<H75 VSWR Model_trackingerror.gif>
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--
Regards
Jeremy
Re: HP 478A Thermistor Sensor. Input return loss and matching

 

Sorry, I made a typo the graph title should say inductance in nanohenries (nH) not uH. The measured Ls for the 1206 capacitor is 1 nH.
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Here's a simulation for the VSWR if the thermistors are not tracking perfectly. This is the case for when one thermistor is 90R and the other is 110R.
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Whilst this still looks really good, the VSWR rapidly degrades to 1.04:1 at 50 MHz if the thermistor tracking degrades to 80R + 120R. I've not show this case as it is probably unlikely to happen unless the sensor has been stressed at some point.
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--
Regards
Jeremy
Re: HP 478A Thermistor Sensor. Input return loss and matching

 

A couple of people have now mentioned that it's possible to swap the internal caps for 0.1uF parts. I'm still not sure what package will be suitable, especially for the series input cap.
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A 1206 SMD package seems huge to me and it isn't the ideal form factor to achieve low series inductance. However, I put a 100nF 1206 class 2 ceramic cap into an SMD test fixture and measured it from 1 MHz to 2 GHz to look at the package inductance and the ESR.
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See the result below. This is pretty much what I've seen in the past from this capacitor type. The series inductance is about 1nH (seen in the right hand graph) and the ESR slowly climbs from a few tens of milliohms up to about 0.5 an ohm by 1 GHz. Above this, the ESR climbs very rapidly and this is normal.
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I also put this into a simulation of a H75 thermistor head and this predicts the VSWR vs frequency. The series resonance is at about 15 MHz and I would have expected to see this up at maybe 30-40 MHz with a different capacitor package. However, these H75 sensors date back a few decades so I'm not sure what technology HP used for these caps. Has anyone taken one (eg a damaged one) apart?
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I haven't included the tiny package inductance of the thermistors so I think the overall inductance will be slightly higher than my crude model below.
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The model assumes that both of the 100R thermistors track accurately together and this allows a very low VSWR between 10 and 20 MHz. However, if they don't track perfectly when the bridge is balanced, then the VSWR will be a bit higher here in reality. One thermistor might be at 90 ohms and the other one might be at 110 ohms for example where 90 + 110 = 200R. This will degrade the VSWR of the sensor.
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--
Regards
Jeremy
Re: 5334A part reference

 

I've dumped the three UVPROMs from my counter. The ROMs are attached here in case they could ever be useful to anyone later on.

The versions, as marked on the stickers, are:

U17 - HPIB Controller: 05334-80007
U19 - Executive Controller: 05334-80003
U29 - Measurement Controller: 05334-80006

Ed


On Mon, May 19, 2025 at 7:53?AM Ed (scskits) via <scskits=[email protected]> wrote:
I do have a DIY replacement oscillator for the 5334A and 5334B.
If interested contact me off group.
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ed



--
Edward Koloski

HP5334A-80006_U29.BIN
HP5334A-80006_U29.BIN
HP5334A-80003_U19.BIN
HP5334A-80003_U19.BIN
HP5334A-80007_U17.BIN
HP5334A-80007_U17.BIN

Re: YIG Oscillator Info?

 

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If you are new to YIG’s? then you should be very careful about the fine tune / FM coil as it does not take any currant to burn it out

And yes you do need a lot of different power supplies to work on a lot of components

Not on Yigs but watch out for bias supplies that must be switched on before the main supply otherwise it is sudden death to the device under test

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Paul

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From: [email protected] [mailto:[email protected]] On Behalf Of Steve J. Noll, WA6EJO via groups.io
Sent: 19 May 2025 20:20
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] YIG Oscillator Info?

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Yes, thank you. Just found one of the YIGs is shown in one of the files, but the connections shown do not jive with the actual unit PCB. Considering requirements of 40V, 20V, 10V, 5V and one or two more, I now realize these are just not worth the time!
Re: YIG Oscillator Info?

 

Yes, thank you. Just found one of the YIGs is shown in one of the files, but the connections shown do not jive with the actual unit PCB. Considering requirements of 40V, 20V, 10V, 5V and one or two more, I now realize these are just not worth the time!
Re: HP8757A Display Problem (Scalar Network Analyzer)

 

An update: I've extracted the 1345A display unit and examined the boards we spoke about yesterday; I powered it using a bench supply I designed and built myself years ago which I use for all this kind of work, so the unit was independent from any other elements of the 8757A analyzer, to produce the "pikes peak" test pattern.
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I saw some suspect solder joints on both of the smaller boards on the side, cleaned them and re-soldered them. I also dismounted the PROM and the two static RAM chips and re-seated them; the RAM's are fine (checked on another unit I have).
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The problem persists, I ran out of time last night and have been busy with other matters today, so my next steps are to check both oscillators (20MHz and 19.66MHz) and the divided-down derived frequencies and also examine the "Vector Done" signal path.
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I am also wondering if the tantalum capacitors (those yellow ones on the boards) may be suspect - I have spare caps which I can replace them with but I cannot think of a way they would be causing this problem, the supply rails are exactly as they should be so they are certainly not short-circuit, but maybe open-circuit or high ESR.
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This is taking a lot of time I could be using on other things so I'm also thinking of finding a replacement 1345A to buy, but that would not be a "real" solution!
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Re: YIG Oscillator Info?

 

开云体育

Have you looked in the ????(? The YIG ?) ?folder on this sight ?

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From: [email protected] [mailto:[email protected]] On Behalf Of Steve J. Noll, WA6EJO via groups.io
Sent: 19 May 2025 18:11
To: [email protected]
Subject: [HP-Agilent-Keysight-equipment] YIG Oscillator Info?

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I have these three HP YIGs to check out. I find zero info on them online. I found the "Operating and Service Manual" for a network analyzer one of them came from... no schematics! (How can a "Service" manual not have schematics?!)? The YIGs: 5086-7538, 5086-7323, and 5086-7268. They have IC sockets for interface so I'm looking for info on what I have to hook up to make them work. All I know is I think they need +20V and -10V, but nothing more. ?? 73, Steve WA6EJO
Re: E4407B schematics

 

also search this group's archive, this exact question has come up multiple times even just these past few months.
YIG Oscillator Info?

 

?
I have these three HP YIGs to check out. I find zero info on them online. I found the "Operating and Service Manual" for a network analyzer one of them came from... no schematics! (How can a "Service" manual not have schematics?!)? The YIGs: 5086-7538, 5086-7323, and 5086-7268. They have IC sockets for interface so I'm looking for info on what I have to hook up to make them work. All I know is I think they need +20V and -10V, but nothing more. ?? 73, Steve WA6EJO
Re: how to convert HP83711B to 83712B!

 

On Mon, May 19, 2025 at 04:30 AM, Ed Marciniak wrote:
I wonder if a dump of the EPROMs would show any interesting SCPI strings that might involve writing to the EEPROM so the coefficients could be written without disassembly while also calculating the checksums.
Indeed, there are such SCPI strings but I couldn't get them working properly as the arguments for those commands are unclear. I did write a software which allows to modify a given EEPROM binary which also automatically updates the checksums. If useful I can upload it.
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Tom
Re: how to convert HP83711B to 83712B!

 

On Sun, May 18, 2025 at 01:02 PM, Sven Schnelle wrote:
One the 8375X series, there's a attenuator calibration table to
compensate each attenuator setting. Does the 8371X have such tables?
Yes it does, and I did re-calibrate them as described by Staffan's document.
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Tom
Re: how to convert HP83711B to 83712B!

 

开云体育

Nice work!? The 83712Bs are less common and more expensive, so that’s a very worthwhile upgrade.? I can see how the empty space reserved for the low-band board was an irresistible temptation.

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And thanks for the heads-up on the Skyworks diode.? HP failures are one thing, but those guys evidently had an HR failure…

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-- john, KE5FX

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From: [email protected] <[email protected]> On Behalf Of tom_iphi via groups.io
Sent: Saturday, May 17, 2025 2:03 AM
To: [email protected]
Subject: [HP-Agilent-Keysight-equipment] how to convert HP83711B to 83712B!

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Hi folks,

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I have converted my HP83711B signal generator into an HP83712B and have added options.

See here how I did it:

Maybe useful to someone or just fun to read.

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Tom
Re: 5334A part reference

 

I do have a DIY replacement oscillator for the 5334A and 5334B.
If interested contact me off group.
?
ed
Re: how to convert HP83711B to 83712B!

 

开云体育

I wonder if a dump of the EPROMs would show any interesting SCPI strings that might involve writing to the EEPROM so the coefficients could be written without disassembly while also calculating the checksums.

There had to have been service software running on a 9845 or a series 200/300 system for factory setup. I suspect it’s not available, but the books left behind for it to run are likely there if found.

From: [email protected] <[email protected]> on behalf of Sven Schnelle <svens@...>
Sent: Sunday, May 18, 2025 3:02:16 PM
To: tom_iphi via groups.io <iphi@...>
Cc: [email protected] <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] how to convert HP83711B to 83712B!
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"tom_iphi via <iphi@...> writes:

> Hi folks,
>?
> I have converted my HP83711B signal generator into an HP83712B and
> have added options.
> See here how I did it:
>
>
> Maybe useful to someone or just fun to read.

Thanks a lot, very interesting read!

I also upgraded my 83752B with a 24V step attenuator, while the original
one uses 15V. Also seems to work fine.

One the 8375X series, there's a attenuator calibration table to
compensate each attenuator setting. Does the 8371X have such tables?
Re: HP 10525H Logic Probe

 

Hi , the hp10525H looks different of the T version , different pcb and some components .
Regards
Maurizio
File /All HP, Agilent and Keysight instruments in folders by part numbers/5000 to 5999/HP 5334A Universal Counter/HP_5334A_ROM_05334-80011.zip uploaded #file-notice

Group Notification
 

The following items have been added to the Files area of the [email protected] group.

By: BI4LBK <chrispotma@...>
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