Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer
Hi, ? I tested this with my 8591A. I used an external generator for the 10 MHz reference. I measured the 300 MHz signal returning to the A15 COUNTER LOCK module. This way, I tested the path from the 10 MHz IN to A15, and the return from A9 THIRD CONVERTER at 300 MHz. ? I measured the 300 MHz return at the spectrum, but kept the PLL closed loop using a T-connector. ? The maximum range of the VCXO was 299.976-300.087 MHz, or 300 MHz -24/+87 kHz, but this is doubled if you measure the 600 MHz output. The RF amplitude of this signal was approximately -4.5 dBm upon arrival at the A15 COUNTER LOCK module. The DC control voltage coming from the A15 COUNTER LOCK module (J4-40) to A9 was -0.253/-13.2 Volts, and -4.645V was the voltage for an accurate input 10 MHz reference. ? For adjustment, you can see from the wiring diagram that R68 presumably allows for range centering. I haven't checked the manual yet, but I did check this potentiometer, as I've had several issues with defective potentiometers in this Spectrum series. ? Yves ? 
? ? After further digging into my Ref Unlock error message on the HP8591A Spectrum Analyzer I have found the following. The 600 MHz SAW oscillator on A9 Third Converter assembly seems to oscillate at only 599.744 MHz on its own (without 10 MHz reference connected). With the 10 MHz reference connected, the frequency only comes up to 599.920 MHz - It does not reach 600 MHz. The VTO_TUNE signal between the Counterclock assembly and the A9 Third Converter assembly is maxed so it can not tune the 600 MHz SAW oscillator any further. Can the 600 MHz SAW oscillator be tweaked in some way or is the next step to replace the A9 Third Converter assembly?
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Also, how is the voltage on your new battery?
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-mark
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Odd that D13 would now be off.? We'll assume the 68230 and related circuitry is ok for the moment.
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Along the same lines as what Yves suggested, you could also try resetting the CRT to DEFAULT SYNC.? Flying blind, it would be:
?
? CONFIG
? Softkey #6 (MORE)
? Softkey #6 (MORE)
? Softkey #3 (DEFAULT SYNC)
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You could also try setting DEFAULT CONFIG:
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? CONFIG
? Softkey #6 (MORE)
? Softkey #4 (DEFAULT CONFIG)
? Softkey #4 (DEFAULT CONFIG)? (second press needed to confirm)
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Another thought is to try resetting the contents of the SRAM completely by grounding the + side of the supercap through a 10 ohm resistor to ground and hold it there for about 10 seconds (obviously with the power off). ?You'll then have to go through the initialization procedure on page 204. ?I know you were trying to avoid doing that in the first place, but it seems the most likely explanation is that something got corrupted in the SRAM during the battery replacement procedure.
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-mark
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On Fri, Apr 4, 2025 at 10:37 AM, KB2LMN wrote:
Mark I took the boards back out and cleaned all the contacts good and seeded them in and out a few times now the lite D13 is off. I do still have the screen issue shown in the video. I also tried what Yves suggested with no luck.
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Andrew
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Mark I took the boards back out and cleaned all the contacts good and seeded them in and out a few times now the lite D13 is off. I do still have the screen issue shown in the video. I also tried what Yves suggested with no luck.
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Andrew
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Re: RF Alignment Failure in Agilent CXA signal analyzer N9000A
Hi, Hardyhansendk.
Thank you for your response, As you mentioned about W9 cal signals, When I tested there I'm getting 50Mhz with -60dB not -25dB, it would be helpful if you share info regarding that. Once again thank you for your response.
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Regards,
San.
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Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer
After further digging into my Ref Unlock error message on the HP8591A Spectrum Analyzer I have found the following.
The 600 MHz SAW oscillator on A9 Third Converter assembly seems to oscillate at only 599.744 MHz on its own (without 10 MHz reference connected).
With the 10 MHz reference connected, the frequency only comes up to 599.920 MHz - It does not reach 600 MHz.
The VTO_TUNE signal between the Counterclock assembly and the A9 Third Converter assembly is maxed so it can not tune the 600 MHz SAW oscillator any further.
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Can the 600 MHz SAW oscillator be tweaked in some way or is the next step to replace the A9 Third Converter assembly?
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Mark yes the display was normal.
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All LEDs should go off once boot is complete and the initial hardware check is finished. ?D13 being left on indicates there is a problem with the 68230 (U57) Parallel Interface/Timer. ?See Table 14-3 in the Assembly Repair manual for LED decoding.
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It doesn't necessarily mean that U57 is bad; it could be something that's being tested that is connected to U57.
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I assume you had a normal display before you replaced the battery? ?Is the SRAM card completely seated?
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-mark
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On Thu, Apr 3, 2025 at 07:58 PM, KB2LMN wrote:
Ok I replaced the battery this am and all went great, yes I did copy the info as the manual states.
my new issue is the display as you will see in this video. I thought maybe I missed a connection when I re-assembled so I took all apart and checked and nothing was disconnected or wrong.
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The Voltages look good according to the Power Supply indicator lights.
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D1 - D16 all lite when powered on and go off with the exception on D13 as I believe this is normal?
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Any suggestions would be appreciated.?
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Hi, ? I think you may have lost the calibration constants, at least the ones related to the display. ? You'll have to do a blind test. The soft buttons near the screen, the top one is #1 and the bottom one is #6. ? CAL MORE (soft button #6) Soft button #4 for vertical adjustment Soft button #5 for horizontal adjustment ? Use the knob or the up and down arrows to see if you can synchronize the image. ? ? Yves
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Ok I replaced the battery this am and all went great, yes I did copy the info as the manual states.
my new issue is the display as you will see in this video. I thought maybe I missed a connection when I re-assembled so I took all apart and checked and nothing was disconnected or wrong.
?
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The Voltages look good according to the Power Supply indicator lights.
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D1 - D16 all lite when powered on and go off with the exception on D13 as I believe this is normal?
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Any suggestions would be appreciated.?
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Hi Jeff. I feel your pain. And FYI, the power supply is a pain to work on. The PCB is held by a number of plastic stand-off type things that you have to squeeze closed and work the board out. But if you go this route, Q1 is a likely suspect.
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I have attached the schematic of the power supply, at least this is what I have seen in the 8920's I've worked on.
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Good luck!
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Mark
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Re: HP 8594E battery power
Yes, the RTC is on the processor board and gets power through the connector to the SRAM board where the battery is located.? When the SRAM card is removed, you lose the time.
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Regardless of the super-cap and any other optional external battery backup steps, I would also recommend going through the calibration constants backup procedure described in the Assembly-Level Repair manual, chpt. 3.? It only take s a few minutes to write down the constants.? If you make a mistake with the battery, your future self will thank you.
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It's also possible to record and recover the cal constants from the output of the GPIB command "CAL DUMP", if you have a PC with a GPIB interface.
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-mark
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On Thu, Apr 3, 2025 at 06:01 PM, Ozan wrote:
On Thu, Apr 3, 2025 at 10:24 AM, KB2LMN wrote:
Anyplace to attach an outside power supply so data doesn’t need to be re-entered when replacing battery??
Andrew
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====
I assume you already found service manual sheet with all the data to be copied to paper for insurance. There is a super capacitor on the battery board, if it is still good it lasts long enough to desolder/solder the battery. For extra safety you can solder a parallel 3V battery with 10k-ohm in series. I think date/time is kept on a different board and it will be lost so don't be concerned if you see date to be wrong after battery change.
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Ozan
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Re: HP 8594E battery power
On Thu, Apr 3, 2025 at 10:24 AM, KB2LMN wrote:
Anyplace to attach an outside power supply so data doesn’t need to be re-entered when replacing battery??
Andrew
?
====
I assume you already found service manual sheet with all the data to be copied to paper for insurance. There is a super capacitor on the battery board, if it is still good it lasts long enough to desolder/solder the battery. For extra safety you can solder a parallel 3V battery with 10k-ohm in series. I think date/time is kept on a different board and it will be lost so don't be concerned if you see date to be wrong after battery change.
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Ozan
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HP8935 displaying AA Memory Battey Low Message
Friends,
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My HP8935 is displaying the AA Memory Battey Low message, but the batteries are not low.? I am wondering if anyone else has experienced this.
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Thanks!
Jeff KC8VFN
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This morning, I tried running it using a DC power supply and that led to it blowing the 15 Amp external fuse for DC power.? As I mentioned yesterday, if you try to use on AC, it blows the external 5 Amp AC fuse.? I have never had the cover off, but that is the decision I need to make now.? Send it off or have a go at myself.? I have a well-equipped lab but am not sure about a schematic for the power supply.? I will need to look for one.? I won't work on much of anything without one.? From what I've seen in response to my inquiries, it seems like Q1 is a possibility.? Will it be a SMD?? I have some SMD rework equipment, but not a ton of experience with it.? I normally work on Ham Radio Equipment, mostly repeaters, not HP test equipment.? Recommendations welcome.?
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Thanks!
Jeff
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HP 8505A OP Manual and Digital Radio Measurements
Sold the VNA, however, have the local ops manual, very handy with?
full view foldout. Also, Digital Radio Measurements text.?
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PM me direct, make offer, shipped media mail.?
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Thanks, Alan?
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Re: Manuals for an HP3456B DMM?
I am not certain it is a 3456B. I got that number from a phone conversation from someone selling a pair of these meters, and a recollection from seeing said meters at a hamfest last year. I will be getting them soon, and will update when I have them in front of me.
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BobH
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Anyplace to attach an outside power supply so data doesn’t need to be re-entered when replacing battery??
Andrew
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Re: Manuals for an HP3456B DMM?
FWIW, I can't put my hands on my '94 catalog at the moment, but the 3456A is no longer in the '95 one - it has the 3457A & 3458A. -Pat
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> ------ Original Message ------
> From: kc0wjn@...
> To: [email protected]
> Sent: Thursday, April 3rd 2025, 11:18 AM
> Subject: Re: [HP-Agilent-Keysight-equipment] Manuals for an HP3456B DMM?
? And your attempt worked. Thanks.
? ?
?
Dave Daniel suggested that he maybe should scan and make
a pdf out of his HP3456<<<A>>> manual.? I was trying to head
that off.
I looked in the following catalogs:
1986 - 3456A
1987 - 3456A
1988 - 3456A
1989 - 3456A
1990 - 3456A
1991 - 3456A
1992 - 3456A
1993 - 3456A
...
1997 - no 3456 model number in catalog
...
1999 - no 3456 model number in catalog
2000 -?
So, if the "B" model exists, it would be in 1994, 1995, or 1996.
The 3458A was the only meter in the 34XX series in 1999.
Searching for HP3456B results in a couple of ChatGPT created
results that don't actually contain 3456"B".
Although the OP hasn't chimed in, I would bet he made a mistake.
I am pretty certain that no 3456B ever existed as a DVM.
-Chuck Harris
On Thu, 3 Apr 2025 05:20:16 -0700 "Radu Bogdan Dicher via "
<vondicher=[email protected]> wrote:
> I've never heard of a 3456B. I don't think there is one. It'd be very
> interesting to learn if that's not so.
>?
> Radu.
>?
> On Thu, Apr 3, 2025, 3:43 AM Chuck Harris via <cfharris=
> [email protected]> wrote:
>?
> > Nice copies of the various HP3456A manuals are available
> > on Ko4bb.com
> >
> > -Chuck Harris
> >
> >
> > On Wed, 2 Apr 2025 23:37:26 -0400 "Dave Daniel via "
> > <kc0wjn=[email protected]> wrote:
> > > Yes. There was a time when a 3458A was on my list of expensive
> > > instruments to acquire for my lab, but I ended up with the 3456A
> > > as an interim solution and it has fulfilled my needs. I wish I
> > > could find a replacement for the small aluminum panel on the RH
> > > side on which the binding posts are mounted because mine is badly
> > > and deeply scratched, but tha's a nit.
> > >
> > > It sounds as if i should scan my 3456A manual and upload a copy of
> > > the PDF to the HP Wiki. I an in the process of scanning a
> > > Tektronix 7934 manual (the foldouts are tedious to properly
> > > scan), so the 3456A manual scan would be queued behind that.
> > >
> > > Everyone should own an HP 345xA, a Fluke 27 and af least one
> > > Simpson 260, lol.
> > >
> > > DaveD
> > > KC0WJN
> > >
> > >
> > > On Wed, Apr 2, 2025 at 22:54 Dave McGuire via <mcguire=
> > > [email protected]> wrote:
> > >
> > > > On 4/2/25 22:48, Dave Daniel via wrote:
> > > > > They made 3455s, 3456s, 3457s and 3458s. I think but am not
> > > > > sure that these were all "A" models, i.e., 3456A. My
> > > > > understanding is that the 3458A is the (or one of) gold
> > > > > standard(s).
> > > >
> > > >? ? The 3458A is indeed the gold standard, and one of the few
> > > > instruments to be made with all three names on the front.
> > > >
> > > > > I own a 3456A.
> > > >
> > > >? ? They are great meters, even (especially?) by today's
> > > > standards.
> > > >
> > > >? ? ? ? ? ? ? ?-Dave
> > > >
> > > > --
> > > > Dave McGuire, AK4HZ
> > > > New Kensington, PA
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >?
> >
> >
> >
>?
>?
>?
>?
>?
?
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Re: Manuals for an HP3456B DMM?
And your attempt worked. Thanks.
Dave Daniel suggested that he maybe should scan and make
a pdf out of his HP3456<<<A>>> manual.? I was trying to head
that off.
I looked in the following catalogs:
1986 - 3456A
1987 - 3456A
1988 - 3456A
1989 - 3456A
1990 - 3456A
1991 - 3456A
1992 - 3456A
1993 - 3456A
...
1997 - no 3456 model number in catalog
...
1999 - no 3456 model number in catalog
2000 -
So, if the "B" model exists, it would be in 1994, 1995, or 1996.
The 3458A was the only meter in the 34XX series in 1999.
Searching for HP3456B results in a couple of ChatGPT created
results that don't actually contain 3456"B".
Although the OP hasn't chimed in, I would bet he made a mistake.
I am pretty certain that no 3456B ever existed as a DVM.
-Chuck Harris
On Thu, 3 Apr 2025 05:20:16 -0700 "Radu Bogdan Dicher via "
<vondicher=[email protected]> wrote:
> I've never heard of a 3456B. I don't think there is one. It'd be very
> interesting to learn if that's not so.
>
> Radu.
>
> On Thu, Apr 3, 2025, 3:43 AM Chuck Harris via <cfharris=
> [email protected]> wrote:
>
> > Nice copies of the various HP3456A manuals are available
> > on Ko4bb.com
> >
> > -Chuck Harris
> >
> >
> > On Wed, 2 Apr 2025 23:37:26 -0400 "Dave Daniel via "
> > <kc0wjn=[email protected]> wrote:
> > > Yes. There was a time when a 3458A was on my list of expensive
> > > instruments to acquire for my lab, but I ended up with the 3456A
> > > as an interim solution and it has fulfilled my needs. I wish I
> > > could find a replacement for the small aluminum panel on the RH
> > > side on which the binding posts are mounted because mine is badly
> > > and deeply scratched, but tha's a nit.
> > >
> > > It sounds as if i should scan my 3456A manual and upload a copy of
> > > the PDF to the HP Wiki. I an in the process of scanning a
> > > Tektronix 7934 manual (the foldouts are tedious to properly
> > > scan), so the 3456A manual scan would be queued behind that.
> > >
> > > Everyone should own an HP 345xA, a Fluke 27 and af least one
> > > Simpson 260, lol.
> > >
> > > DaveD
> > > KC0WJN
> > >
> > >
> > > On Wed, Apr 2, 2025 at 22:54 Dave McGuire via <mcguire=
> > > [email protected]> wrote:
> > >
> > > > On 4/2/25 22:48, Dave Daniel via wrote:
> > > > > They made 3455s, 3456s, 3457s and 3458s. I think but am not
> > > > > sure that these were all "A" models, i.e., 3456A. My
> > > > > understanding is that the 3458A is the (or one of) gold
> > > > > standard(s).
> > > >
> > > >? ? The 3458A is indeed the gold standard, and one of the few
> > > > instruments to be made with all three names on the front.
> > > >
> > > > > I own a 3456A.
> > > >
> > > >? ? They are great meters, even (especially?) by today's
> > > > standards.
> > > >
> > > >? ? ? ? ? ? ? ?-Dave
> > > >
> > > > --
> > > > Dave McGuire, AK4HZ
> > > > New Kensington, PA
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
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KB2LMN
Cubdriver