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Date
Re: 8594E Cal Signal not Found ?

 

That is the latest firmware on KO4BB.
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Look at the size of the four HEX files when loaded into your programmer. ?You will need (4) 27C020-150 2Mbit (256kbyte) EEPROMs to hold them all.
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The firmware doc is wrong in saying that you need (4) 1Mbit EEPROMs. ?I think it's only true for version H (95.02.21) or older. ?And if you use anything other then 2Mbit EEPROMs, you need to restrap the EEPROM socket selects (see schematic). ?Save yourself a headache and stick with 27C020-150.
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I did the same upgrade from G to L on one of my 8595E analyzers: (2) 27C020-150 to (4) 27C020-150. ?Worked fine. ?I bought (4) 27C020-150 for the upgrade and saved the old EEPROMs in case something went wrong.
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-mark
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On Sat, Apr 5, 2025 at 01:17 PM, KB2LMN wrote:

Well I believe I found the newest software
?
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My question is I only have 2 EPROMS in my 8594E do I need 4 or can the files be combined some how I to 2. If not I will need to pick up 2 EPROMS.
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Andrew
Re: 8594E Cal Signal not Found ?

 

Well I believe I found the newest software
?
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My question is I only have 2 EPROMS in my 8594E do I need 4 or can the files be combined some how I to 2. If not I will need to pick up 2 EPROMS.
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Andrew
Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer

 

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Hi Anders,

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I'm glad to hear that you were able to fix your Spectrum's 600 MHz VCXO circuit and get it working.

?

Yves

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Re: Manuals for an HP3456B DMM?

 

The 3456A is a very nice meter, and I think the only of
its sort HP ever certified as a transfer standard.

There are a couple of failures you should watch for.

First, the more desirable is the meter without the fan,
if you have a fan, it is a much older model, and I don't
know much about those.

DO NOT TOUCH ANY OF THE BOARDS WITH YOUR BARE FINGERS!

DO NOT TRY TO CLEAN PCBs, UNLESS YOU WANT TO SPEND HOURS
SCRUBBING WITH PURE 99% IPA. and even then, you may fail.

The large axial leaded filter capacitors tend to dry out,
and may need replacing. Check them with an ESR meter.
When they go bad, the meter will count erratically.

These are very high impedance meters. They will drift
when open circuit, in all but the highest DCV range.

The big reed relay that routes the ohms current tends to
get its contacts coated with something that makes it
unreliable. I usually remove a coil wire, and put a
wetting current through the contacts, and buzz them by
applying 25Hz, or so to the coil. I put a volt meter
across the contacts (mechanical, not dvm) and when the
needle gets to 50% of the wetting voltage, you are done.

10ma, with a series resistor is a good wetting current.

The front panel push switch that switches between front and
rear panel input is known to never work again, if you ever
push it. It is bound to need cleaning with some deoxit.

The trim pots that are for calibration are under the
input connector front panel, and are wire wound, and get
dirty. If you find you need to adjust them, get some
deoxit slider lube into them first.

The AC is calibrated for 1KHz, not 50/60Hz. There is a
serious noise problem at or near 50/60 hz, so that if you
put, say, 61Hz input in 60Hz land, your lower digits will
count up and down with the beat note.

If you ever find a way to fix that, please let us know!

Enjoy your new meters!

-Chuck Harris


On Fri, 04 Apr 2025 10:57:54 -0700 "BobH via groups.io"
<wanderingmetalhead@...> wrote:
I picked up the meters today. They are model 3456A. Both work, but
need some cleanup. The power switch on on unit sticks on and the
front/rear terminal switch is dirty. A quick checkout shows both
reading within a few mV of my 34401A. Now I need to port my GPIB
tools to talk to them.
Re: 8594E Cal Signal not Found ?

 

Yves thanks for sharing that info after I read the ENTIRE how to input constants section I found at the very end a work around so I’m good now. Now I’m just looking for the newest firmware version and then I’m done with this one and onto an 8591 I picked up.
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Andrew
Re: 8594E Cal Signal not Found ?

 

Mark I did get everything working last night thank to your help I appreciate it! I ran it through some tests and it passed them all so the firmware was my next leap. Fortunately I have done some chip programming so this one should be an easy fix/ upgrade for me. I looked around and can’t find the G 980615 file for upgrade purposes.
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Again thanks for sharing your expertise it would have taken me much, much longer to figure this all out on my own.
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Andrew
Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer

 

I am very impressed by your knowledge Yves!
?
My spectrum analyzer is fixed now - at least sort of fixed.
My fix was to replace C75, change from 3.3 pF to 2.2 pF.
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Conditions after the fix:
300 MHz VCXO is 299.922 MHz with 10 MHz Ref disconnected. When 10 MHz Ref is connected it is 300.000 MHz.
Maxed VTO_Tune (-13.27 Volt) gives VCXO of 300.026 MHz.
VTO_TUNE with connected 10 MHz Ref is -8.61 Volt (still some area left to -13.27 Volt).
CAL FREQ, CAL AMPTD and CONF TEST goes through without any problem.
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My Q12 bias voltage is 5.168 Volt so that was ok from start.
CR81 capacitor was not fitted in my unit.
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It was very fun to dig into this problem with your help!
This is the first time I use the HP spectrum analyzer - I have only used a TinySA Ultra before.
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Anders
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?
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Re: 8594E Cal Signal not Found ?

 

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?

I repaired an 8591A for a friend two weeks ago, and he had the same problem.

In his case, it had lost its calibration constants due to a low battery.

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What caused the signal not found or LOCK OFF SRQ110 problem was that the units after a PRESET weren't dBm but mV, and also that the flatness data was empty...no value.

For flatness, I had entered a value of -1 for the entire band.

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After fixing these two issues, I was able to run CAL FRE and CAL AMP without any problems.

?

I'm not saying this is the problem with your 8594E, but out of curiosity, do either of these two cases apply to you regarding flatness and units after a PRESET?

?

Yves

,_
Re: 8594E Cal Signal not Found ?

 

Hi Andrew,
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It's ok to have 2 or 4 EEPROMs for version G (94.03.15).? You can read about the various versions and EEPROM part numbers here (original doc #08590-90324):
?
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The latest version according to that doc is M (991130), but the latest out there in the various archives that I'm aware of is L (980615).
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I don't recommend messing with firmware upgrades until everything is resolved with the self-cal.? One thing at a time.
?
-mark
?
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On Fri, Apr 4, 2025 at 07:35 PM, KB2LMN wrote:

Mark, my 8594E only has 2ea firmware chips U24 & U27, is this normal? Everything I seem to find about this unit says 4 chips? I was trying to see if I had the latest firmware installed.
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Re: 8594E Cal Signal not Found ?

 

Mark, my 8594E only has 2ea firmware chips U24 & U27, is this normal? Everything I seem to find about this unit says 4 chips? I was trying to see if I had the latest firmware installed.
Fail over input board for the HP-5087A distribution amplifier

 

Recently saw a you tube video of an HP-5087A with an HP designed (I think) fail over amplifier board.
I have never seen any documentation on the board before.
The board takes a signal from two of the input channels, say A and B and if the A input fails fails, it switches over to the B input.
Going to try a modernized version shortly if there is any interest.
Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer

 

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Anders,

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So, in green is the active bias stage, R66 serves as the current sense.

In my case, I have 5.186V, which means that the collector current of Q13 is about 9.8mA.

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In blue is the oscillator with CR1 as a varicap for frequency control.

Now, the frequency range of your circuit is too low, I would be tempted to try adjusting with R68, but make a mark on R61 to note the current state of the adjustment, because if it doesn't work, you can reset it to its original position.

Since the frequency is lower than expected, and if R68 doesn't change anything, then the capacitive load is too large, I would suspect the varicap CR1 as the first suspect.

?

You can always experiment by disconnecting C81; the frequency should rise higher.

?

Yves

?

?

De?: [email protected] <[email protected]> De la part de Anders L??v via groups.io
贰苍惫辞测é?: 4 avril 2025 14:19
??: [email protected]
Objet?: Re: [HP-Agilent-Keysight-equipment] Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer

?

Thanky you for the valuable information Yves!


I have now checked a bit further and made sure the VTO_TUNE reached the A9 Third Converter assembly ok.
My VTO_TUNE voltage varies between -0.43 (10 MHz Ref disconnected) to -13.27 Volt (10 MHz Ref connected).

?

My 300 MHz VCXO range is 299.872 MHz (10 MHz Ref disconnected) to 299.959 MHz (10 MHz Ref connected) - A total range of 88 kHz which is a bit smaller than yours 111 kHz.

This time I have meassured the frequency at the Cal Out to make the meassurement easier.

?

I have desoldered and checked the R68 potentiometer and it was fine.

Do you have any further good ideas?

Best Regards
Anders
Re: 8594E Cal Signal not Found ?

 

Thanks Mark, ya I did all that but did just see this so I will try next.
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Instrument firmware expects the cal output signal to be 300 MHz ± 2 MHz.Sometimestheinstrument default data is not able to tune the cal signal within this range and a “cal signal not found” message may appear on screen. Perform a cal output bypass check by pressing Frequency,-37, Hz, Cal, Cal Freq. This will bypass the cal check and start by calibrating the sweep ramp.
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Andrew
Re: 8594E Cal Signal not Found ?

 

The workaround for the "Cal Signal Not Found" error is covered in the Assembly Level Repair manual.
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If you had to reload all the correction constants, I would start with the "Analyzer Initialization" section in that manual (namely: setting DEFAULT CONFIG) and go from there, if you haven't already done so.
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-mark
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On Fri, Apr 4, 2025 at 02:51 PM, KB2LMN wrote:

After replacing battery I entered the Time Base Correction, Frequency Response Correction & Step Attenuator Corrections.
Now when I go to perform Cal Freq or Cal Amptd I’m getting a Cal Signal Not Found.
I checked the CAL OUT and I’m seeing 300.000824MHz -20dBm on my Spectrum Analyzer.
Input using an HP E4432B Signal Generator set 300MHz -20dBm I’m seeing 300.8MHz at -28dBm.
As I change the Span I get different frequency’s showing?
?
Andrew
?
?
?
8594E Cal Signal not Found ?

 

After replacing battery I entered the Time Base Correction, Frequency Response Correction & Step Attenuator Corrections.
Now when I go to perform Cal Freq or Cal Amptd I’m getting a Cal Signal Not Found.
I checked the CAL OUT and I’m seeing 300.000824MHz -20dBm on my Spectrum Analyzer.
Input using an HP E4432B Signal Generator set 300MHz -20dBm I’m seeing 300.8MHz at -28dBm.
As I change the Span I get different frequency’s showing?
?
Andrew
?
?
Re: HP 8594E new issue

 

Great, glad the sync reset worked!
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It makes me wonder, however, if the CRT parameters were corrupt in SRAM, then what else might be corrupt? ?I would take a quick pass through the calibration constants to verify they are still ok. ?And it wouldn't hurt to do a FREQ/AMPLITUDE self-cal when you get a chance.
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Really 6.3V on the battery?? ?It should be around 3.3V for a new battery.
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-mark
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On Fri, Apr 4, 2025 at 01:26 PM, KB2LMN wrote:

Reset worked Config, 6, 6, 3.
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Thank you!!!!
Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer

 

Thanky you for the valuable information Yves!

I have now checked a bit further and made sure the VTO_TUNE reached the A9 Third Converter assembly ok.
My VTO_TUNE voltage varies between -0.43 (10 MHz Ref disconnected) to -13.27 Volt (10 MHz Ref connected).
?
My 300 MHz VCXO range is 299.872 MHz (10 MHz Ref disconnected) to 299.959 MHz (10 MHz Ref connected) - A total range of 88 kHz which is a bit smaller than yours 111 kHz.
This time I have meassured the frequency at the Cal Out to make the meassurement easier.
?
I have desoldered and checked the R68 potentiometer and it was fine.

Do you have any further good ideas?

Best Regards
Anders
Re: Manuals for an HP3456B DMM?

 

I picked up the meters today. They are model 3456A. Both work, but need some cleanup. The power switch on on unit sticks on and the front/rear terminal switch is dirty. A quick checkout shows both reading within a few mV of my 34401A. Now I need to port my GPIB tools to talk to them.
?
Re: HP 8594E new issue

 

Reset worked Config, 6, 6, 3.
?
Thank you!!!!
Re: HP 8594E new issue

 

6.3Vdc
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