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Re: HP 5086-7906 YTO
¿ªÔÆÌåÓýYves, thanks for the info about the 2nd converter? After having installed the one bought on the bay?I checked?the original one?on the bench and it?seems to work normally
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I'm starting to suspect the blindness on the LOW BAND was due to a bad connection I did when the repair was suspended years ago ¡ ouch !
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Meanwhile I'm investigating?a certain deafness on the HIGH BAND (from 2.4 to 11 dB)
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I measured the insertion loss of the SYTF I had realigned and found figures?from 5.2??to? 8.5 dB on the range? 3 to 6 GHz
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These figures?seem not too bad?and?the AMP CAL routine should be able to recover them ...unless there is some hardware problem in the generation of the tuning current (I performed the insertion loss measurements by manually tuning? with an external precision power supply)
Will see ...
Adri
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Re: HP 141T Power Supply Help Needed
¿ªÔÆÌåÓýSounds good to me. ? Mike ? From: [email protected] <[email protected]> On Behalf Of Frank Mashockie
Sent: Friday, September 13, 2024 3:01 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ? Dave, ? The schematic for the HP 141T shows all voltages referenced to ground.? If that is the case, you know the voltage at the positive side of C6.? It is listed as 5.9VDC.? So you can infer that the voltage across C6 is 18.6V.? From there, you can find what the AC voltage across the winding should be, correct??? ? Also, in the schematic they show collector of Q9 at 6.61VDC and collector of Q4 at 5.9VDC.? But apparently Q4 and Q9 are tied together at the collector by wire 968.? What is the reason for the 0.6V drop?? Or is this an error??? ? -Frank |
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Re: HP 141T Power Supply Help Needed
Dave,
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The schematic for the HP 141T shows all voltages referenced to ground.? If that is the case, you know the voltage at the positive side of C6.? It is listed as 5.9VDC.? So you can infer that the voltage across C6 is 18.6V.? From there, you can find what the AC voltage across the winding should be, correct???
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Also, in the schematic they show collector of Q9 at 6.61VDC and collector of Q4 at 5.9VDC.? But apparently Q4 and Q9 are tied together at the collector by wire 968.? What is the reason for the 0.6V drop?? Or is this an error???
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-Frank |
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8513A T/R test set attenuator question
Greetings,
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I have an 8510 VNA system running well with an 8515A S-parameter test set.
I'm trying to convert a spare 8511A (sampler only box) into an 8513A T/R test set.
That should just involve adding a 26 GHz directional bridge, a few hard lines + attenuators.
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I found a few discrepancies in the 8513A Service Manual regarding installed attenuators.
Would a kind soul be able to confirm what is actually installed in the 8513A T/R test set?
A picture of the internals would be great start.
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Thanks for the bandwidth,
Benoit Robert
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Re: HP 141T Power Supply Help Needed
¿ªÔÆÌåÓý
Make sure you also replace the gas voltage reference (used in low serial number instruments) with a zener.? My favorite is a TL431 plus a 60V-80V zener to stay within the TL431's max rating.? The zener has a large temperature coefficient, put it inside the
feedback loop.? This combo is more stable than a straight zener.? This can be a simple two-terminal board you tack across the tube without removing the tube.? See ?topic and photo album titled ¡°141T?reference?replacement".
A supply with gas reference outputs a high spike at turnon, which will trigger your crowbar.? If you look at the crowbar in the 8552B plugin, it has two thresholds and a timer, specifically to work around this.? It's ghastly, usually the HP engineers did better.
Dave Wise
From: [email protected] <[email protected]> on behalf of Michael Bafaro via groups.io <m.bafaro@...>
Sent: Friday, September 13, 2024 8:19 AM To: [email protected] <[email protected]> Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ?
Dave,
Yes the sockets have caused intermittent connections.? The sockets are form Keystone Electronics P/N 4608 which are still available.? It appears that the brass contacts get annealed over time and the insertion force on one of the units I worked on had gone to ZERO!? After taking the screws out of the collector, the transistor would have fallen out if it were not for the sill pad insulator.?? With new sockets the transistors fit tight! Yes the voltage across C6 has to be measured at the cap because it is floating relative to ground.? ?I am thinking of designing a small board that will crowbar the -12.6 output if it goes beyond -14V.? I wonder if anyone would be interested in such a module? Mike -----Original Message----- From: [email protected] <[email protected]> On Behalf Of Dave_G0WBX via groups.io Sent: Friday, September 13, 2024 10:04 AM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed Take care with taking voltage measurements around the 141T PSU -12.6V regulator. It is not "ground referenced" at the input.? It is essentially a floating Positive regulator with it's Positive output tied to "Ground", resulting in C6 "floating" at some arbitrary voltage on it's Positive side, though it's Negative side "Should" be at (or very close to) the -12.6 Output voltage. To measure the raw DC voltage, you need to measure across C6, not from it's +ve terminal to Ground! Re power transistor sockets.? Over the years I've always found them to be a major cause of all sorts of weirdness.? Best abandon them, as once the pin sockets have lost their spring temper, you'll never get a reliable contact between them and the power transistor Base and Emitter leads.? Just fit the device conventionally, taking care with any needed insulation between the device case, and the heatsink, including insulating washers for the fixings etc. If the collector of Q4 does get shorted to "Ground", the -12.6V will end up at an uncontrolled -ve voltage more(or less) equal to the raw voltage across C6.? Not good for some of the down stream loads, such as perhaps, the CRT flood gun filaments!? Especially if there is no (or faulty) downstream crowbar protection, that should fire and "Blow" F4 if such a thing happens. Apologies if I'm preaching to the converted, I'm not trying to teach anyone to suck eggs!? Just to raise awareness re the layout of that particular regulator circuit, as it is not entirely straightforward. 73. Dave B. -- Created on and sent from a Unix like PC running and using open source software: |
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Re: HP 141T Power Supply Help Needed
Dave,
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Yes the sockets have caused intermittent connections. The sockets are form Keystone Electronics P/N 4608 which are still available. It appears that the brass contacts get annealed over time and the insertion force on one of the units I worked on had gone to ZERO! After taking the screws out of the collector, the transistor would have fallen out if it were not for the sill pad insulator. With new sockets the transistors fit tight! Yes the voltage across C6 has to be measured at the cap because it is floating relative to ground. I am thinking of designing a small board that will crowbar the -12.6 output if it goes beyond -14V. I wonder if anyone would be interested in such a module? Mike -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Dave_G0WBX via groups.io Sent: Friday, September 13, 2024 10:04 AM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed Take care with taking voltage measurements around the 141T PSU -12.6V regulator. It is not "ground referenced" at the input. It is essentially a floating Positive regulator with it's Positive output tied to "Ground", resulting in C6 "floating" at some arbitrary voltage on it's Positive side, though it's Negative side "Should" be at (or very close to) the -12.6 Output voltage. To measure the raw DC voltage, you need to measure across C6, not from it's +ve terminal to Ground! Re power transistor sockets. Over the years I've always found them to be a major cause of all sorts of weirdness. Best abandon them, as once the pin sockets have lost their spring temper, you'll never get a reliable contact between them and the power transistor Base and Emitter leads. Just fit the device conventionally, taking care with any needed insulation between the device case, and the heatsink, including insulating washers for the fixings etc. If the collector of Q4 does get shorted to "Ground", the -12.6V will end up at an uncontrolled -ve voltage more(or less) equal to the raw voltage across C6. Not good for some of the down stream loads, such as perhaps, the CRT flood gun filaments! Especially if there is no (or faulty) downstream crowbar protection, that should fire and "Blow" F4 if such a thing happens. Apologies if I'm preaching to the converted, I'm not trying to teach anyone to suck eggs! Just to raise awareness re the layout of that particular regulator circuit, as it is not entirely straightforward. 73. Dave B. -- Created on and sent from a Unix like PC running and using open source software: |
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Re: HP 141T Power Supply Help Needed
Take care with taking voltage measurements around the 141T PSU -12.6V regulator.
It is not "ground referenced" at the input.? It is essentially a floating Positive regulator with it's Positive output tied to "Ground", resulting in C6 "floating" at some arbitrary voltage on it's Positive side, though it's Negative side "Should" be at (or very close to) the -12.6 Output voltage. To measure the raw DC voltage, you need to measure across C6, not from it's +ve terminal to Ground! Re power transistor sockets.? Over the years I've always found them to be a major cause of all sorts of weirdness.? Best abandon them, as once the pin sockets have lost their spring temper, you'll never get a reliable contact between them and the power transistor Base and Emitter leads.? Just fit the device conventionally, taking care with any needed insulation between the device case, and the heatsink, including insulating washers for the fixings etc. If the collector of Q4 does get shorted to "Ground", the -12.6V will end up at an uncontrolled -ve voltage more(or less) equal to the raw voltage across C6.? Not good for some of the down stream loads, such as perhaps, the CRT flood gun filaments!? Especially if there is no (or faulty) downstream crowbar protection, that should fire and "Blow" F4 if such a thing happens. Apologies if I'm preaching to the converted, I'm not trying to teach anyone to suck eggs!? Just to raise awareness re the layout of that particular regulator circuit, as it is not entirely straightforward. 73. Dave B. -- Created on and sent from a Unix like PC running and using open source software: |
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Re: HP 5086-7906 YTO
Hello Yves,
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This second converter assembly is also used in the 8563E and also ESA E4407B spectrum analyzers. In fact I think it is common for all 6.5/13.5/26.5GHz versions. Mine had failed in the E4407B and it looks like it is related to an incorrectly manufactured transformer inside the assembly. I attached the Agilent Service Note related to this issue. Part number affected is 5086-7958. Thanks for the nice PDF with all explanations. Regards, Razvan On 13/09/2024 07:51, Yves Tardif via groups.io wrote:
Hi Adri, |
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Re: HP 5086-7906 YTO
¿ªÔÆÌåÓýHi Adri, ? A friend of mine had a faulty 8595E, the problem comes from the option card 130. But I took the opportunity to look at the second converter, so here are some details on this module. ? Regards Yves ? De?: [email protected] <[email protected]> De la part de alfa beta ? hello Yves, ? As proof of the "deafness", while all the calibration routines, including the CAL YTF routine are performed without problems, the CAL MXR is not completed and gives the message CAL: HARMONICS INSUFFICIENT In fact I attach a screen of the 300MHz calibration signal from which it would seem that the very last harmonics are missing ?
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Re: Thermal Couple attached to heat sink
That's Thermocouple, to be precise.
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Jim Ford, Laguna Hills, California, USA?
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Thermal Couple attached to heat sink
On the A7A3 board in the 8663A? Sig Generator there is a heat sink with a slot that holds a thermal coupler. The slot is filled with thermal compound. Underneath the TC and the heat sink was a square insulator.? Mine has deteriorated beyond recognition. Is the function of this just to press the TC against the heat sink, or is it also a thermal sink?? I¡¯m sure the same assembly is used on lots of HP boards. Thanks, John |
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Re: HP54610B No Display
¿ªÔÆÌåÓýI can¡¯t remember if this was implemented in the firmware, but sometimes the ¡°key-down¡± power-up would clear some of the boondoggles and get the display back. ? Basically from a power-off state, press & hold a front panel key while you toggle the power switch ON. ? Best Regards, ? Bob Groschen Colorado Springs ? From: Steve Cheal via groups.io
Sent: Wednesday, September 11, 2024 9:44 AM To: [email protected] Subject: [HP-Agilent-Keysight-equipment] HP54610B No Display ? Hi I switched on my HP54610B scope today having not used it for a couple of years. The fan started (possibly a bit noisier and a bit slow but I¡¯m not sure), and the display remained blank, even after turning the brightness to max. It worked fine previously. I have downloaded a manual to start troubleshooting it, but before I start that I thought I would just ask if anyone is aware of any common/simple known problems that might cause this. Many thanks if you can help. Steve M0STC ? ? |
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Re: HP54610B No Display
I don't know if the 546xx family of scopes suffers this problem, but the 545xx family has a battery maintaining the cal data and clock. When the battery dies, you get a short lived message on the screen about no cal data or something similar. If your scope has a CRT display, the message is gone before the CRT warms up enough to see and it looks like a dead scope. The way to check for this is to do a key down power up, hold any front panel key down while you turn the power on. That will put a different message up that requires user input before it goes away. If you get the key down screen lit up, the battery is a good first guess. |
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Re: HP 141T Power Supply Help Needed
¿ªÔÆÌåÓýBill, ? CR1 and CR2 are mounted on the heat sink at the lower right side of the unit.? These are stud mounted diodes.? The anodes of these are connected to the power transformer with 2 heavy white wires.? The cathodes are connected together with a white blue / grey wire and they first go to the collector of Q4 and then off to the filter cap C6 with the same color wire.? As you say the voltage at C6 is almost 0 then there must be an open from the diodes to the cap C6.? There should be a connection from the center tap of the power transformer to the ¨C of C6.? The fact that you see the same voltage at the cathodes and anodes of CR1 and CR2 says that they are not connected to C6.? The diodes and cap C6 should show a difference in reading from the anodes (AC) to the cathodes (DC) because the diodes and cap form a peak detector so the cap should charge to the peak of the sign wave 17 x 1.414 = 24VDC.? An other thing to check is the status of C6, it may be dried out and have no capacitance.? Parallel it with an other cap of the same size. Or if you have an LCR bridge read it out.? This has to be a wiring breakage or something simple like that.? ? I have a 141T that was just given to me and it has some bad transistor sockets at the pass transistors Q1, 2, 3, and Q4.? They are made by Keystone Electronics with the part number 4608.? The are intermittent and are a bear to replace as they are riveted in! ? Mike ? From: [email protected] <[email protected]> On Behalf Of Bill Berzinskas
Sent: Wednesday, September 11, 2024 6:44 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ? Finally got this thing back on my bench and a little free time.? ?Assuming CR1 and CR2 are in the back left of the case near the diode board, I see about 17v here both on the AC and DC sides.? ? That seems a little low, but also seems workable?? ? ? This suggests something along wire 968 or maybe 945.? ? I do get continuity from pcb back to the diodes, so that seems good.? ? ?I'll trace through this section a bit more though.? ? |
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Re: HP 141T Power Supply Help Needed
Finally got this thing back on my bench and a little free time.? ?Assuming CR1 and CR2 are in the back left of the case near the diode board, I see about 17v here both on the AC and DC sides.? ? That seems a little low, but also seems workable?? ? ? This suggests something along wire 968 or maybe 945.? ? I do get continuity from pcb back to the diodes, so that seems good.? ? ?I'll trace through this section a bit more though.? ? |
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Re: HP 8568B from hell to Heaven... a restoration story!
The restoration of the HP 85662A was a bit more complicated. At this point, I had one of the most affordable HP8568Bs in the world, fully functional. Now, I¡¯d like to dedicate myself to a deep realignment to make it work perfectly within specifications, but here I¡¯ll need some help... it¡¯s my first time working with such complex hardware. But we¡¯ll make it! |
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Re: 5343A equivalency to 5351B
¿ªÔÆÌåÓýI like the LED Displays on the HP-5343A over the LCD Display on the HP-5351B. I sold the HP-5351B for that reason (besides being big for a counter), and restored the HP-5343A - mostly Power Supply Cards Capacitors and some Resistors. ? Ross ? From: [email protected] <[email protected]> On Behalf Of Steve - Home
Sent: Wednesday, September 11, 2024 6:13 AM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] 5343A equivalency to 5351B ? Hello John, ? As Yves has said, there are no equivalent connectors on the 5351B. The 8350/83592 are quite old and the calibration procedure calls for equipment (5343A) of the same era.? The more modern 5351B does not have the connectors you are looking for. That is the reason I keep a 5343A on my bench.? ? ? Steve ? ?
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Re: HP54610B No Display
¿ªÔÆÌåÓýNo display at all suggests a possible PSU issue? Always the most likely cause of such things.. I would suggest to start there.. ? Just my 2p worth! Regards Nigel ? From: [email protected] <[email protected]> On Behalf Of Steve Cheal via groups.io
Sent: 11 September 2024 16:43 To: [email protected] Subject: [HP-Agilent-Keysight-equipment] HP54610B No Display ? Hi I switched on my HP54610B scope today having not used it for a couple of years. The fan started (possibly a bit noisier and a bit slow but I¡¯m not sure), and the display remained blank, even after turning the brightness to max. It worked fine previously. I have downloaded a manual to start troubleshooting it, but before I start that I thought I would just ask if anyone is aware of any common/simple known problems that might cause this. Many thanks if you can help. Steve M0STC ? |
Frank Mashockie
