Re: 8665B noisy signal & Cal Errors
Question.
What was the span/division, and sweep speed (need to state / div, or full sweep rime) when that video was taken?
Do the spurious sidebands become less wayward. If the sweep is line triggered?
There is information there, that may help.
73.
Dave B (UK)
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Re: HP 8568A Spectrum Analyser not booting up. Both INSTR CHECK Leds on
On 9/23/24 16:35, azpo1928r@... wrote: Also, i completly forgot to mention, if i flip the power off then on pretty fast i get random stuff on the screen, like lines, garbeled text-looking stuff and things like that. It always did that. They last for multiple seconds. That's a great way to blow up the power supply in just about anything electronic. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: HP 8568A Spectrum Analyser not booting up. Both INSTR CHECK Leds on
I just realised something really important :
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The service manual says "if the ADRS'D LED flashes without INSTR PRESET pressed it indicates A13 is functionning but cannot communicate with the controller processor"
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The ADRS'D Led is indeed flashing on my unit... never realised it wasn't normal...
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Btw, INSTR PRESET button is working just fine, i've tested it.
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So that probably narrows it down to A15 right?
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If i remove A13 (hpib board) it doesn't blink anymore but still got the same two instr check leds.
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Also, i completly forgot to mention, if i flip the power off then on pretty fast i get random stuff on the screen, like lines, garbeled text-looking stuff and things like that. It always did that. They last for multiple seconds.
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I just ordered a cheap usb logic analyser, i will do signature analysis checks.. in the meantime i'm searching for A15 and A14 boards online... people are selling them for more than double the price i paid for the whole unit (the 2 parts + the two cables + 4 volumes of manuals about it).
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Seems cheaper to just buy a non-working RF part and try swapping the boards like you said...
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Re: HP 141T Power Supply Help Needed
There is another design from Philips, they replaced a 103V reference tube, with a circuit based on two transistors, two resistors and a low voltage Zener diode, I keep meaning to try this someday, pdf attached.
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Note: The resistor values will need altering for the 82V reference, used in the older HP 140 & 141 series mainframes.
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David
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Re: HP 141T Power Supply Help Needed
Dave, ? How do I view ¡°141T reference replacement¡±?? Are there PCBs available? If so what is the price? ? Mike ?
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From: [email protected] < [email protected]> On Behalf Of Dave Wise Sent: Monday, September 23, 2024 11:24 AM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ? Already done, see ¡°141T reference?replacement" topic and photo album.
Bill, ? The 141T that I purchased from Valuetronics now has a new fan and the power transistor sockets have been replaced. Now the 1A fuses on the 8552 IF module are popping.? I built a fixture that I can monitor the basic supply voltages with out the plugins in and the 141T covers on.? ?It turns out that there is an over voltage crowbar circuit in the IF module that fires at -15V.? I took some startup scope traces and they show that the -12.6V over shoots to -15.2V and the +100 overshoots as well.? Since these are tracking regulators and the basic reference is the neon tube in the +100V supply I tested it during startup and it overshoots badly.? Enclosed are some of the startup scope traces I took.? I am working on a circuit that will replace the neon tube with a 50V Zener in series with a TL431.? Since the 50V Zener will be inside the control loop its temp coefficient will not be an issue.? I will publish the TL431 design later in the week.? ? Mike ? ? CONV mode is the only functional mode, i get blooming at almost any intensity / persistence setting in storage mode unless its so low its basically OFF.? ? ? ?? ? Beware of using the 141T in "Conv" mode, you cannot see if the intensity is set too high & causing damaging the storage mesh. You need to start with it in storage mode and turn intensity down to stop the blooming, then switch to "Conv", if there is any blooming, the intensity is set too high, do not increase the intensity once in "Conv" mode. Attached are the numerous warnings in the 1973 manual and the label that is attached to the cover of my 141T.
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Re: 8665B noisy signal & Cal Errors
Special Function 320, instrument self test.?
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Re: Efratom MBF distrib amps
On 9/22/24 17:50, Wilko Bulte wrote: My pal Robert PE1MJA took the time to reverse engineer the MBF so all credits to him! And no guarantees there are no mistakes, goes without saying I suppose..
The trick is playing with the caps to peak the filter to 10 instead of 5 MHz. Ahh, this is very handy, thanks Wilko. Please extend my thanks to Robert as well. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: HP 141T Power Supply Help Needed
Already done, see ¡°141T reference?replacement" topic and photo album.
Dave Wise
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Bill,
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The 141T that I purchased from Valuetronics now has a new fan and the power transistor sockets have been replaced. Now the 1A fuses on the 8552 IF module are popping.? I built a fixture that I can monitor
the basic supply voltages with out the plugins in and the 141T covers on.? ?It turns out that there is an over voltage crowbar circuit in the IF module that fires at -15V.? I took some startup scope traces and they show that the -12.6V over shoots to -15.2V
and the +100 overshoots as well.? Since these are tracking regulators and the basic reference is the neon tube in the +100V supply I tested it during startup and it overshoots badly.? Enclosed are some of the startup scope traces I took.? I am working on a
circuit that will replace the neon tube with a 50V Zener in series with a TL431.? Since the 50V Zener will be inside the control loop its temp coefficient will not be an issue.? I will publish the TL431 design later in the week.?
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Mike
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CONV mode is the only functional mode, i get blooming at almost any intensity / persistence setting in storage mode unless its so low its basically OFF.? ? ? ??
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Beware of using the 141T in "Conv" mode, you cannot see if the intensity is set too high & causing damaging the storage mesh. You need to start with it in storage mode and turn intensity down to stop the blooming, then switch to "Conv",
if there is any blooming, the intensity is set too high, do not increase the intensity once in "Conv" mode.
Attached are the numerous warnings in the 1973 manual and the label that is attached to the cover of my 141T.
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Re: HP 141T Power Supply Help Needed
i either get no trace at low intensity or blooming just after a background green fill.? ? ?I've been going through the 8552/8554 so I haven't paid it much mind but I do need to come back to it.? ? Will look over the A5 details soon.?
Does it "Bloom" with the trace intensity set to minimum?
It does look like the storage sub-system needs attention.
Dave B. (UK)
--
Created on and sent from a Unix like PC running and using open source software:
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Re: 8665B noisy signal & Cal Errors
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Quick update: I put the unit in self test (Special 320) and got code +2,433,311. From the code list, this appears to need MW Loop Adjustment.
I will do this cal and report back!?
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Re: HP 141T Power Supply Help Needed
Bill, ? The 141T that I purchased from Valuetronics now has a new fan and the power transistor sockets have been replaced. Now the 1A fuses on the 8552 IF module are popping.? I built a fixture that I can monitor the basic supply voltages with out the plugins in and the 141T covers on.? ?It turns out that there is an over voltage crowbar circuit in the IF module that fires at -15V.? I took some startup scope traces and they show that the -12.6V over shoots to -15.2V and the +100 overshoots as well.? Since these are tracking regulators and the basic reference is the neon tube in the +100V supply I tested it during startup and it overshoots badly.? Enclosed are some of the startup scope traces I took.? I am working on a circuit that will replace the neon tube with a 50V Zener in series with a TL431.? Since the 50V Zener will be inside the control loop its temp coefficient will not be an issue.? I will publish the TL431 design later in the week.? ? Mike ?
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From: [email protected] < [email protected]> On Behalf Of Bill Berzinskas Sent: Friday, September 20, 2024 11:30 AM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ? CONV mode is the only functional mode, i get blooming at almost any intensity / persistence setting in storage mode unless its so low its basically OFF.? ? ? ?? ? Beware of using the 141T in "Conv" mode, you cannot see if the intensity is set too high & causing damaging the storage mesh. You need to start with it in storage mode and turn intensity down to stop the blooming, then switch to "Conv", if there is any blooming, the intensity is set too high, do not increase the intensity once in "Conv" mode. Attached are the numerous warnings in the 1973 manual and the label that is attached to the cover of my 141T.
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Re: 8665B noisy signal & Cal Errors
Quick update: I put the unit in self test (Special 320) and got code +2,433,311. From the code list, this appears to need MW Loop Adjustment.
I will do this cal and report back!?
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Now I'm looking for papers/manuals of the HP8568B and the 8565OA quasi peak adapter and the 8444A opt 059 tracking generator. Because the best person doesn't have that. Where can I find it or who has it and wants to share it. I am very grateful. Mvg
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Re: HP 8568A Spectrum Analyser not booting up. Both INSTR CHECK Leds on
Thanks for your answer,
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If i unplug the bus cable i still get both LEDs.
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The processor clock is also running, i've checked it yesterday. 10MHz signal is present, it gets divided into two 5MHz out of phase signals which are also there.
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There's only ONE weird thing i've found when doing tests.
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Manual says "UMC Pin (A15U13 pin 25) should be high when INSTR PRESET button is pressed"
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The thing is that i've got the exact opposite. The "idle" state is HIGH instead of being low and when i push on INSTR PRESET, it oscillates back and forth from high to low and then stops and goes back HIGH instead of low.
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I can't really know for sure if it's supposed to do that, maybe someone here has an hp8568a and could try probing the UMC pin? That would help me a lot
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Other than that, everything else i've tested seems fine. I also checked every single wire inside the bus cable, all good.
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Checked all voltages for ripple (in case of a dead capacitor) , all good too.
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8665B noisy signal & Cal Errors
I have an 8665B with what I can best describe as a noisy signal; three side lobes to each side of the carrier, before disappearing into the noise floor. They are visible on <3GHz, but really shows as soon as the instrument switches to 3GHz and above. They are not stable dance around on the spectrum analyzer though the carrier signal is stable. I'll link to a video below:?
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https://youtu.be/TcHVk-WHKps?si=PK1RgEfZCQklWx1z
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There are also a few CAL errors on startup. It's random which one shows, but it's commonly the first one:?
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1,078,311 COAX DSC
3,503,311 (Turn to conditions not covered by diagnostics)
3,504,311 FRAC-N
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As of now, I have not done much troubleshooting. I just pulled a few of the cards and looked for obvious issues (caps, burned traces etc.). I intend to go through the power supply as I have read of issues there, particularly bad caps, causing signal problems.?
Now for the good news: I have a fully functioning 8665B which I can swap cards with for testing if necessary though it would be nice to minimize this if possible. If anyone has suggestions I'm all ears. These are not the easiest units to work on, and there isn't much in the way of documentation or info out there on them.?
Pete?
W4PJB
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Re: Help request - how to test an HP8350B RF plugin YIG
Thank you, Paul.
I have checked and calibrate the power supplies in 8350B, I also changed the 3 battery cells with new ones in the same case.
The bad joints maybe is a case, but with the A8 from the working plug-in the YO Coil Current Source Waveforms in
A8TP6 is present!!
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With the other A8, it isn't.
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In the working plug-in, both A8 are working!!!!
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IDC is the same when I change the A8
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John
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Hello members,?
I introduce myself, I'm a new member and my name is Harry.?
I was able to buy a HP8568B with peripherals for my biggest hobby, and that is receiving TV signals and I want to be able to see them on the Spectrum.
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Mvg
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Re: Help request - how to test an HP8350B RF plugin YIG
OK going from memory the 83592A RF plug-in is actually a very compact unit with a lot to it The yig signal should be available on the rear of the plug in so I would start there next try the output on the fundamental Yig frequency band ? I assume you have checked the 8350 with another plug in and all is OK as the stand by battery¡¯s are a killer for the 8350 when they age best advice is to remove the stand by battery¡¯s? if they are in a sorry state? then the 8350 frame could suffer from bad joints and connections also the IDC will be at risk of intermittent faults ?I have recently scraped an A version it has repaired 8 other sweepers / plugins ? I love these sweepers but faults can be tricky to sort out Paul ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of i.brokos via groups.io
Sent: 22 September 2024 22:20
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Help request - how to test an HP8350B RF plugin YIG ? I'm trying to repair a 83592A RF plug-in I have bought it from eBay with many components missing, and I have completed it. Furthermore, I have changed the 300uF cap on A8 board, it was in it. I looked for a signal in the front output or the AUX output, NO RF power - All Bands. From the manual, I have the troubleshooting procedure (see photo) I have measured on A13AI YO BIAS PCB test points (See photo) YO Coil Current Source Waveforms in A8TP6 (see photo) is flat/noise ! With another A8 Board from a working plug-in, the YO Coil Current Source Waveforms in A8TP6 is present, but again there is NO RF power - All Bands I tried the working plug in with the A8 from the plug in I try to repair (not working plug in) the YO Coil Current Source Waveforms in A8TP6 is present, and the plug in is working!!!! That means that the two A8 boards are working !! I can't understand why on the no working plug in the one A8 the YO Coil Current Source Waveforms in A8TP6 is present and in the other doesn't when in the working plug in both A8 YO Coil Current Source Waveforms in ?? Furthermore, I can't measure TP "G" Can I disconnect the J2 without burning the YO (if it is working!) and take the measurement of TP "G" for -2Vdc? OR it is not necessary the YO is failure ? If there is any suggestion on the next steps, it will help
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Re: HP 8566B Not Showing Any Signal
I'm picking up a new attenuator tomorrow, and until then, I have nothing I can do to help, so I thought I'd do one of the common mods that have been recommended for the A20, and that is to replace C7, a 10uF/25V cap. I didn't have the exact cap so I replaced it with a 220uF/50V cap thinking that more voltage is better and more capacitance should help to stabilize the supply more.
I also installed a 10dB attenuator between the CAL signal and the input of the LIMITER. To my shock and amazement, I can now run RECALL 8 and I see a 100MHz signal there. Granted the front end attenuator is out of circuit, but this is more than I've seen in the past. The shape of the signal is odd. See attached pic.
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If I widen the span to ~3MHz, the shape becomes as expected.  ?
Selecting RECALL 9 produces no useful result. I'm not able to adjust the trimmer enough to get the trace on the screen.  ?
Pic of the 10dB attenuator inline.  ?
I was also able to get MUCH further into the SHIFT+W calibration routine this time so I feel like I'm making progress!
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Re: Operating Manual 8901A wanted
Hello George,
thats really great. Thanks a lot.
Kind regards from Germany
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Ernst
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Dave McGuire
factory
Paul Bicknell
Brad Jackson