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  1. HP-Agilent-Keysight-Equipment
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Date
Re: DIY: Repair of HP Step Attenuators

 

How many of what size/type would be needed to replace all the ones used in an 8566B stack? I'd be interested in buying a set to refurbish my spec an when it becomes necessary.

DaveD
KC0WJN


On Wed, Mar 26, 2025 at 15:29 John Griessen via <john=[email protected]> wrote:
On 3/26/25 10:18, Don Bitters via wrote:
> you will find a detailed step by step procedure with HPAK part nos. and Apple Rubber part nos. for the o-rings.

Is anyone going to be buying 0-rings now?? I'd like to do a group order since I now have an old, mostly working 8566B SA.
These can be mailed around in letters for $.73...
Re: DIY: Repair of HP Step Attenuators

 

On 3/26/25 10:18, Don Bitters via groups.io wrote:
you will find a detailed step by step procedure with HPAK part nos. and Apple Rubber part nos. for the o-rings.
Is anyone going to be buying 0-rings now? I'd like to do a group order since I now have an old, mostly working 8566B SA.
These can be mailed around in letters for $.73...
HP 435B, Zero Carryover Test - How noisy should it be?

 

Hey All,
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I noticed what looked to be a zero issue with my 435B, so I thought I'd run it through the zero carryover test (OSM 4-6) to see what was going on.
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While the meter meets all the ranges given for zero carryover, it occasionally doesn't meet the requirement:
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4. Press the front panel ZERO and wait for the meter indicator's position to stabilize. Verify that the DVM reads 0+/- 0.9 mVdc. Release the ZERO switch.
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My output seemed quite noisy, so I used the statistic function to look at it over 100 samples, and what I saw was:
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  • Max 0.533 mVdc
  • Min -1.006 mVdc
  • Avg -0.150 mVdc
If I had been quick to look at it, then I could have moved on to the next part of the test and never noticed that over some time it exceeds the +/- 0.9 mVdc requirement.
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Should this be less noisy??
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The only fix from the manual is to change the factory selected resistors A4R12 & A4R16 (the A1 assembly is a recommended factory replacement), and it does pass the actual +/- span for each step of the range control so I'm hesitant to make any changes to those.
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Any thoughts or guidance appreciated.
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TonyG
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Re: DIY: Repair of HP Step Attenuators

 

I used 0.5mm CS X 1.0mm ID 70 durometer from theoringstore.com on an attenuator from my HP 8560A
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They are 0.22ea. with a $5.00 minumum order and shipping runs $9.95 so you will have to order 22 to meet their order requirement.
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I'd order extra and store them in an airtight bag. They are really tiny!
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Sam
W3OHM
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Re: DIY: Repair of HP Step Attenuators

 

I have done over a hundred repairs of the 3332xA/B style attenuators. In the file listing in this site you will find a detailed step by step procedure with HPAK part nos. and Apple Rubber part nos. for the o-rings.
You may search the files by my name, or HP 8566 attenuator repair, HP attenuator repair, any of which should find the file.
The short of it is with the attenuator lid off and the contacts in the up (closed) position push the push rod toward the ball opening in the contact slot and lift the contact off from the push rod, when you have them all disconnected pull the solenoid down to the open position. Then you can push the push rods out of the solenoid slots replace the rubber o-rings and put them back into place, reversing the above procedure.

Don Bitters
Re: DIY: Repair of HP Step Attenuators

 

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The original o-rings were 1.0mm ID,2.2mm OD for a cross section of 0.6mm.

None of the ones listed are exactly the correct size.?
Re: DIY: Repair of HP Step Attenuators

 

There's good older threads that go into some detail on this. I repaired one set a few years ago, posting here, and I recall the "surgery" aspect of the project. Mechanically, maybe one of the more demanding projects in this type of work. I used watch o-rings, but there are more appropriate materials and sources of o-rings for this specific purpose.?

I was also able to find a very good video of the procedure on youtube, and I think there are several others available.?

Good luck with the project.?

Radu.?


On Tue, Mar 25, 2025, 11:40 AM ROBERT LEVY via <boblevy4321=[email protected]> wrote:
HiI just disassembled my hp8648 attenuator 33322-60011.
I found the little rubber orings have broke.
I need to know exactly how to disconnect the rods that the orings are on from the contact, without breaking anything.
Thank you to ? Microwaveengineer1968??? for an excellent write up.
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I found this link to the orings ? ?
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Thank you
Bob
Re: DIY: Repair of HP Step Attenuators

 

Which size should I select on that page?
I have stuck attenuator sections in three different instruments, seems to be a common problem.
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Marko Cebokli
Re: DIY: Repair of HP Step Attenuators

 

HiI just disassembled my hp8648 attenuator 33322-60011.
I found the little rubber orings have broke.
I need to know exactly how to disconnect the rods that the orings are on from the contact, without breaking anything.
Thank you to ? Microwaveengineer1968??? for an excellent write up.
?
I found this link to the orings ? ?
?
Thank you
Bob
Re: 89605 / 89606 cal file

 

Awesome and thank you!
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I bricked two E1439C digitizers from a bad firmware update and developed a procedure to fix those.
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I need to write a small program to reset the serial number.?
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The A1 (main board) cal date is also lost. The A3 cal date is retained (on a 23C02 I2C EEPROM).
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I wonder if the A3 board has attenuation data.
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On the A1 board, I don’t see much for adjustments. Being an ADC, if the voltages for references are correct they don’t require adjustment. If they’re wrong then that’d be a repair. I recall seeing a counter le markings for capacitors. I’d guess in the same way as an (Tektronix) oscilloscope having a lug to clip a probe onto and the probe having a couple of trimmers to adjust for minimum under/overshoot, perhaps the only necessary adjustment is the input termination to achieve minimum harmonic distortion of a sine wave, and with a square wave input, a specific ratio of relative power levels.
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The VISA API has no documented call that I’ve seen for updating cal dates.
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i don’t suppose anyone has seen a calibration procedure for the E1438/E1439, but it’d be great if someone could confirm any of my suspicions.
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I plan on sharing some cliffs notes and raw flash images extracted from an E1439A and the image I put on the E1439C to unbrick it.

what worked for me to not brick after putting the image on there was to have edited the model number and serial information before resoldering the chip, and then upgrade to B.01.02 firmware and then B.02.01 firmware (the versions might be different depending on serial range).
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I don’t know what all the differences are between the E1439C and E1439A, but I did notice a 1.2V SOT-23 reference attached to two pins of a CPLD and the third lead had a short wire attached to a third pin on the same.
Re: HP3325A Trouble, Calibration FAIL 2 & 3

 

I changed Q219 and its complementary transistor. Now I can adjust the 7.5Volts on F3. The amp is now fixed, but the A-CAL Fail error for square and triangle is still present.
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The output is correct, sync out as well, amplitude into a 50 Ohm load is ok, on sine, square and triangle & ramp
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When switching to ramp function something curious follows: The display goes off, the ramp function is visible on the scope, but it 'sweeps'.
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Picture 1: relay board, relays are clickking, are these types they reliable? The yellow relays are often mentioned to be cleaned, my could not be opened.
Picture 2: sinus 1kHz, lokks as expected.
Picture 3: ramp moving with about 0.5Hz.
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here is a video: shows the moving of the ramp and then flips to the correct curve? for a second.
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Outputs at the analog switches are as expected, all voltages as well.
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The self test works except the AC fail, FAIL 2, FAIL 3
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The manual says this is 60% of the controller.?
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Any advices waht to test now? ROM/RAM?
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Or has anyone spare? boards for the 3325A to exchange and for testing ?
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IMG_9335.MOV
IMG_9335.MOV

Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer

 

Hi Anders
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Just go to the Files section i have been uploaded the Clip to 8590/91A
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Br
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Johnny
Re: E4402B SA power problem - need DC socket connections

 

Hello,
Have a look on the messages " Agilent E4404B Spectrum Analyzer With Dead PSU Repair?" in 2024, it use the same power supply
Best regards
Eric
Re: microscope / high magnification camera options for soldering, faults, and other examinations/inspections

 

I later suspected that 15x would be too much. I'll have a look for AO570/145.
Thanks.
Renaud
Re: How to I disassemble the HP/Agilent 8495B attenuator ?

 

sorry, mine has N-type connectors and looks exactly as this one
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Re: How to I disassemble the HP/Agilent 8495B attenuator ?

 

Thanks, I have the manual, mine has no screws on each end, for? a? picture please see
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Re: microscope / high magnification camera options for soldering, faults, and other examinations/inspections

 

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Hi Steve,
Thanks for that advice. Why are 145 eyepieces better please? It seems 147 are very common.
Best regards,
Renaud

The 145 eyepiece is 10x. The 147 is 15x. The AO570 body has magnifications from .7x to 4.2x, so the effective magnification with the 10x eyepiece is 7x to 42x. With the 15x the range of magnification is 10.5x to 63x. ?The 42x magnification is plenty and the 7x is a very useful wider field of view.?

The AO catalogs actually call for the AO 184 eyepiece if you want a 15x eyepiece for the AO 569 or AO 570. The AO147 eyepiece was for the American Optical Cycloptic stereo microscope. Since the AO engineers spec’d the 145 and 184 for the AO 570 I suspect there are differences appropriate for those microscopes.
Re: How to I disassemble the HP/Agilent 8495B attenuator ?

 

Do you have a manual attenuator or the electronically switched one?
There are 4 screws on each end of the attenuator, if you have SMA/3.5mm connectors, then remove the nuts on those connectors, the cover plate between the connectors, and that will expose the 12-16 screws that hold the top cover with the attenuator pads on it. You will need to loosen at least one end plate to take the
top cover plate/attenuator plate off.
A lot of this information is in the HP/Agilent/Keysight Microwave Accessory catalog and in the HP 8495B Operating and Service manual, yes it does contain theory of operation, schematics, parts breakdown, and parts listing. A .pdf of the manual is attached.

Don Bitters
Re: FS 8660 plug in's

 

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Forgot to attach, sorry,

Gary

WA2OMY

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From: Gary Hitchner <talgarth@...>
Sent: Monday, March 24, 2025 3:43 PM
To: '[email protected]' <[email protected]>
Subject: FS 8660 plug in's

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List,? FS -

Three plug in’s ?used in 8660’s.

2)- 86603A ?one has phase modulation capability.? These are the high frequency units that go to 2600 MHz.

1)- 86633B, ?Modulation plug in.?

These plug in’s were all in use and working about a year ago when the 8660;s were retired, maybe one has a bad attenuator step.

Sold as is, but as pictured and complete,?? $150.00 for all three shipped to your door, US only, L48.

Gary

WA2OMY

8660-2.jpg
8660-1.jpg

Anyone have the 17090C Measurement Graphics Software for the 7090A Plotter

 

Hey All,
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I asked over on VinHPcom but apart for a pointer to the 17090B Software up on HPMuseum I didn't hear much back, so I thought I'd ask here as well.
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The C version of the software apparently works with Series 300 machines so I'm interested in trying to see if it works with my Viper machine.
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So if anyone has a copy I'd appreciate it if I could snag one from you.
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Thanks,
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TonyG
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