Re: HP 141T Power Supply Help Needed
Mm that did something, not all the way but in a positive direction.? ?In conv mode, I see something that looks like a horizontal scan but off screen.? ?Out of curiosity I turned the vertical position trimmer and I see a line!? ? ?No vertical though.? ?
I think the 141T had a storage CRT and that looks like flooding. Thats when the storage gain typically on the front panel is too high. Not good to leave it that way for long. Paul WB8TSL
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As a general observation - how incredibly?useful this conversation has turned out. As with just about any conversations here. All this is making me think and rethink my bench and workspace configuration. Some great ideas, best practices, "do nots," etc.? I personally think I have a great "working model" - and some visiting friends were very positive of what I did with my limited space, so I may have hopefully?inspired?others (they said as much) - but there's always a lot of "room" for improvement (no pun intended).?
One criteria that is very important to me is how warm and friendly this space is. I'd absolutely not trivialize that aspect. To most of us, I think it's just this "safe space" where we feel great having fun with our hobby (for all of us, very serious hobby!). A contorted, dysfunctional, hostile space does no one any favors.?
Light is another aspect to consider. I am currently using very bright LEDs (there's no such?thing as too much light at the bench!), but EMI and other garbage and noise is a terrible byproduct of that. A whole lot of money and time can be spent on just mitigating that. And when you align FM tuners (uV of signal) or do metrology applications, this noise can be a determining factor.? Radu.?
As for magnetic influence: keep your Rb reference oscillators away from magnetic fields. It probably does not show in everyday use but the Rb units are susceptible to magnetic fields.
Wilko
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Re: HP 141T Power Supply Help Needed
Just looked online and it is a storage tube persistence may be turned way up. Turn storage mode off?
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As for magnetic influence: keep your Rb reference oscillators away from magnetic fields. It probably does not show in everyday use but the Rb units are susceptible to magnetic fields.
Wilko
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Re: HP 141T Power Supply Help Needed
I think the 141T had a storage CRT and that looks like flooding. Thats when the storage gain typically on the front panel is too high. Not good to leave it that way for long. Paul WB8TSL
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Took me a while to work out why a 16500C LA display wobbled when I pushed it further back on the bench.
Eventually realised it was a metcal soldering iron supply, which still has a magnetic field even when nominally 'off'.?
?
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Probing deep and/or narrow into a given unit for troubleshooting
Hi all,
I was wondering of asking for thoughts and ideas on probing deep into some units, or maybe just through a narrow clearance. What I'm thinking of is primarily for use with a DMM (vanilla troubleshooting), though maybe scope probes and others could be considered. But the latter is not my priority.?
?
I have a variety of probes, from "witches hats," to "spring hooks" to many others I don't really even know how to call. I got a bunch and I'll never get tired to look for more and diverse ones. I absolutely think there's never enough tools for probing at a bench. My "silver bullet" is this: , but even this is far too large for some low clearance situations. But its length allows me to reach depths nothing else I have here comes close. Everything else is up to about 3" reach.?
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Sometimes it comes down to having extender cards, or made ejecting a card, attaching (including soldering) a wire and then probing it once the card is back in there. But that's not always possible. Especially with microwave or mm modules, I am weary of disturbing them too much, and there's always more mechanical aspects to messing with them.?
?
What are some creative and crafty solutions others have found useful? Maybe some miraculous tools you've found??
?
Thank you,
Radu.?
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Add in SystemVerilog if one is contemplating FPGA/ASIC work. DaveD KC0WJN
Thanks for all the fish.
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
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On Sep 19, 2024, at 16:03, Roy Thistle via groups.io <roy.thistle@...> wrote:
? On Thu, Sep 19, 2024 at 09:11 AM, Frank Mashockie wrote:
I've been considering going into an online master's program for EE.
If your boss is not paying for it... It's expensive.
2 to 3 years to complete, on average.
?
Say 50,000USD total cost, on average... and up... for many good US schools.
Georgia Tech is... about the lowest cost... 10,000USD total cost.
?
Everyone is different... but IMO... the average person... depending on which? specialty they want... needs to have a strong background in
calculus... as in vector, complex, and differential equations...? linear algebra... numerical methods... statistics.
?
Computer science skills are required too.
Programming in Python or C
Simulations in software packages like Pspice
HDL like Verilog, or VHDL
?
Not to mention a strong background in
circuit analysis
devices
?
probably other stuff I forgot too.
?
?
?
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Thanks for the feedback Roy. I really appreciate it. So I have a solid foundation of math/physics through my chemistry degree. Calc III, dif equations, quantum chemistry. The math I'm not worried about. I also feel comfortable in using most of the hardware an EE student might come in contact with. Software is a different story. I have zero experience with python or CAD. But I know I can learn. My company does subsidize tuition. However, I might fall into a grey area. We are a biotech company so I'm not directly making the company money but I am keeping their costs down. I could argue a degree in EE could translate into better understanding of the equipment which could in turn mean more costs savings. But you bring up excellent points! -Frank?
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Re: HP 141T Power Supply Help Needed
Replaced q15 and the crt is at least trying to do something.??? Ordered a hv probe but wondering if maybe this is related to deflection amps.? ?Doesn't seem good so shut it down after the Pic.? ? Focus Doesn't seem to do much.? ?
On Wed, Sep 18, 2024, 2:35?PM Bill Berzinskas via <bberzinskas= [email protected]> wrote: Thanks for that feedback Dave.?
At this point in my struggle with this machine, nothing about it surprises me.? ?It could have been hit by lightning for all i know.? ? :-P?
One bit of good news, the modules do appear to be working.? I was able to view the scan and vertical outputs on my scope and it does look as i'd expect.??
Nice little mid week surprise for me there.??
I can't see what could destroy Q15, except perhaps C18 shorting.
Dave Wise
I don't have a HV probe currently, but its on my shopping list.? ? I'm going to go with 0v at the moment though, given the state of Q15.??
I guess I'm just wondering?if I should expect other damage to have occurred when this part failed.? ??
I will replace Q15 this week, get a probe and report back though!?
On Wed, Sep 18, 2024 at 10:59?AM Michael Bafaro via
<m.bafaro= [email protected]> wrote:
Bill,
?
Q15 is the FET that is in the HV regulator circuit.? The gate to the other leads will read open if the ohm meter is connected to back bias the junction.? The question is what voltage is present at the control
grid of the CRT?? If you have a high voltage probe you can measure it directly at the green lead on the PCB that goes to the CRT socket.? I measured -2580.? What voltage do you see??
?
Mike
?
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Checking things out last night in the LV side of the HV supply, I saw on the edge of Q15 a small delamination. Very tough to see in that tight space but just enough to warrant further?investigation.? ?I pulled Q15 and a sizable chunk
was blown out and barely hanging on, so it's physically OPEN between pins 1 and 2.
I've ordered a replacement.? Anything else to be concerned with in this area in such a situation?? Q13 and 14 don't seem to be damaged as far as I can tell, at this time.? ??
?
On Tue, Sep 17, 2024 at 9:27?AM Bill Berzinskas via <bberzinskas=[email protected]> wrote:
Probably not related strictly to the PSU, so happy to make a new thread if needed.? ?
I've gone over the A5 board at a high level.? ?Checked all the test points and all but #7 appear to be as expected on the scope.
One of the schematics has voltages at the wiring pins, and those also look ok.? ?I have not checked per-node voltage within the circuit yet.? ??
Is this "fairly conclusive evidence" that A5 is generally OK?? ?I don't want to dwell on it, I'd thought that maybe Blanking or Pulse were having issues?
but now i'm thinking not.? ??
More power supply related, I don't see any oscillation on the HV oscillator.? ?The labelled 7v is closer to 12v so I'm thinking the problem is around Q13, 14 or 15.? Q15 looks kind?of not good, seeing .1v breakdown with a DMM diode test in-circuit.? ?I know
thats?not the best test, but it does seem to work for most of the other transistors I've tested.??
?
The worst bugs make the instrument diverge from the schematic, often in ways that would look like nonsense if you drew it there.
"From over 40 years of fault finding and repair experience in a wide range of electronic products, not just instrumentation,
the weirdest symptoms often have a really simple root cause!"
This has been my experience as well! Makes it very easy to go down a rabbit hole. Which is why I always do a thorough visual
inspection first. Also checking mechanical components of switches, pots, etc. Giving them a good clean right off the bat and testing those first can save you a lot of headache.
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Re: Probe Cables for 16801A Logic Analyser
What Card do you have in it?
?
I am pretty sure any of the later grey cables will work.
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Such as:
?
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168xAx, 169xAx,?1691xA ( which are used in various 198XX Units )?
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All used the same pod cables & probe ends.
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How many do you need? I may have one.
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?
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On Thu, Sep 19, 2024 at 09:11 AM, Frank Mashockie wrote:
I've been considering going into an online master's program for EE.
If your boss is not paying for it... It's expensive.
2 to 3 years to complete, on average.
?
Say 50,000USD total cost, on average... and up... for many good US schools.
Georgia Tech is... about the lowest cost... 10,000USD total cost.
?
Everyone is different... but IMO... the average person... depending on which? specialty they want... needs to have a strong background in
calculus... as in vector, complex, and differential equations...? linear algebra... numerical methods... statistics.
?
Computer science skills are required too.
Programming in Python or C
Simulations in software packages like Pspice
HDL like Verilog, or VHDL
?
Not to mention a strong background in
circuit analysis
devices
?
probably other stuff I forgot too.
?
?
?
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Thanks! I can remember back at Marconi I once thought I had trashed an expensive (and brand new!) Mi 6500 amplitude analyser because I had set it down quite firmly on top of an old microwave sweep generator. When I switched them both on, the CRT display of the 6500 was squished and distorted up into one corner of the CRT. It looked like it was ruined... I was little more than a spotty student at the time and I was quite upset and worried that I had caused some expensive damage to the 6500. What would my new boss say? Then an older and wiser colleague calmly told me to slowly lift up the 6500 a few inches above the sweeper. The display recovered to normal and it was the huge magnets used in the sweeper below that had caused the CRT to distort.
?
I can also recommend anyone to grab a LW or MW portable radio and hold it near your modern test gear, especially anything with a large digital display. Listen out for any interference caused to the radio. Some of the worst offenders are my TTi power supplies. They emit a lot of RF interference for a couple of feet or so. Because of this I have always had to be careful when placing my old homebrew 198kHz offair frequency standard on my workbench. I have a sweetspot on one particular shelf where there is no interference from any of the modern test gear. In other places, the offair standard won't work at all as it uses an internal ferrite rod antenna and this is very prone to nearby fields from test equipment.
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One of my programmable PSUs is really poor in terms of emitted interference across LF and up into VHF. I'm amazed this model passed an EMC test when it was being designed. I suppose it may have a failed cap somewhere but it isn't that old.
?
?
?
?
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Re: Free to good home, HP 5423A system + manuals and spares
Dave,
?
Some info:
I have working copies of the firmware tapes and can duplicate them to 3M QIC80 tapes.
With some minor modification you can let the 5423/5420 system work with QIC80 tapes.
The systems are build around a HP 1000 M-processor with 48/64/128kW memory installed.
Every time you cold start the system it will load it's OS / Firmware from tape, with the original HP tapes that won't work anymore.
That's why I modified my system and copied the firmware tapes to QIC80 tapes, in my case 3M DC2120.
If you need a working copy of this let me know.
?
-Rik
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I agree, I found out the hard way when I was in my late teens with a scope and a PSU and couldn¡¯t figure out why I had fluctuation measurements/traces....
Never do it now. ?
Regards
Nigel
Sent from my iPad by banging a nail into a piece of wood...
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On 19 Sep 2024, at 20:18, Richard Knoppow via groups.io <dickburk@...> wrote:
The arrangement of equipment can be important in several ways; heat is one of them. Another is the radiation of magnetic fields from power transformers which can induce hum in stacked equipment. Grounding is another, one can create hum loops or RF loops when gear is stacked. A problem which is sometimes forgotten in arranging ham gear is vibration induced in a receiver from a loudspeaker placed on top of it. Generally not a good place for a speaker. So, I think your advice and training is very important. Thank you for the reminder.
On 9/19/2024 12:09 PM, jmr via groups.io wrote:
In case this is of any interest, in my first job (at Marconi many years ago) I was taught how to arrange RF test equipment on a workbench and anyone who didn't follow the official guidelines was soon advised by a colleague how to set things up better.
These days test equipment is going to be more thermally stable, but back then, an RF power meter had to be mounted where it wasn't on top of any other test gear (especially a PSU) where the extra thermal gradient could contribute to drift. The same rule applied to network analysers, bench multimeters and frequency counters.
Since then, I always try and put a network analyser at the bottom of a bench stack of test gear (rather than higher up) and at home I made a custom undershelf to support a bench DMM and another one for a power meter and this keeps them away from thermal gradients. I don't really need this degree of care for home use, but back in the days when I worked at Marconi, these were the guidelines.
I would definitely recommend this even today in the case of a network analyser (even a decent HPAK or R&S model) but modern power meters and DMMs are going to be more immune to thermal drift these days unless one is doing really critical measurements over a long time period. At work, a frequency counter is rarely needed and I very rarely have one on my bench here at home, but the same guideline applies to a counter. Keep it away from other test gear in order to minimise drift.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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The arrangement of equipment can be important in several ways; heat is one of them. Another is the radiation of magnetic fields from power transformers which can induce hum in stacked equipment. Grounding is another, one can create hum loops or RF loops when gear is stacked. A problem which is sometimes forgotten in arranging ham gear is vibration induced in a receiver from a loudspeaker placed on top of it. Generally not a good place for a speaker. So, I think your advice and training is very important. Thank you for the reminder.
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Show quoted text
On 9/19/2024 12:09 PM, jmr via groups.io wrote: In case this is of any interest, in my first job (at Marconi many years ago) I was taught how to arrange RF test equipment on a workbench and anyone who didn't follow the official guidelines was soon advised by a colleague how to set things up better.
These days test equipment is going to be more thermally stable, but back then, an RF power meter had to be mounted where it wasn't on top of any other test gear (especially a PSU) where the extra thermal gradient could contribute to drift. The same rule applied to network analysers, bench multimeters and frequency counters.
Since then, I always try and put a network analyser at the bottom of a bench stack of test gear (rather than higher up) and at home I made a custom undershelf to support a bench DMM and another one for a power meter and this keeps them away from thermal gradients. I don't really need this degree of care for home use, but back in the days when I worked at Marconi, these were the guidelines.
I would definitely recommend this even today in the case of a network analyser (even a decent HPAK or R&S model) but modern power meters and DMMs are going to be more immune to thermal drift these days unless one is doing really critical measurements over a long time period. At work, a frequency counter is rarely needed and I very rarely have one on my bench here at home, but the same guideline applies to a counter. Keep it away from other test gear in order to minimise drift.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
In case this is of any interest, in my first job (at Marconi many years ago) I was taught how to arrange RF test equipment on a workbench and anyone who didn't follow the official guidelines was soon advised by a colleague how to set things up better.
?
These days test equipment is going to be more thermally stable, but back then, an RF power meter had to be mounted where it wasn't on top of any other test gear (especially a PSU) where the extra thermal gradient could contribute to drift. The same rule applied to network analysers, bench multimeters and frequency counters.
?
Since then, I always try and put a network analyser at the bottom of a bench stack of test gear (rather than higher up) and at home I made a custom undershelf to support a bench DMM and another one for a power meter and this keeps them away from thermal gradients. I don't really need this degree of care for home use, but back in the days when I worked at Marconi, these were the guidelines.
?
I would definitely recommend this even today in the case of a network analyser (even a decent HPAK or R&S model) but modern power meters and DMMs are going to be more immune to thermal drift these days unless one is doing really critical measurements over a long time period. At work, a frequency counter is rarely needed and I very rarely have one on my bench here at home, but the same guideline applies to a counter. Keep it away from other test gear in order to minimise drift.
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On Thu, Sep 19, 2024 at 05:03 AM, Yves Tardif wrote:
The ideal, for me would have been to have 2 rooms, one for storage only and one for the lab with a clearer work table.
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Yes, that's how I've set up my workroom. I don't really have much choice though as my workroom is quite small. If I put it all in this main workroom I doubt I'd be able to get into the room let alone do any work :)
?
However, it is definitely much harder to keep the room tidy if there is lots of bench space available though. It soon fills with clutter and I try and tidy up fairly regularly. Otherwise the advantage is soon lost.
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It also allows me to realise which test gear really needs to be disposed of, because I have quite a few items that have remained in storage for a long time. Other items probably make the trip back and forth maybe once a week or so.
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The other rule I try and adhere to is to have no tool or component storage on the main workbench. I do allow RF adaptors and other small items to accumulate to some degree though.
?
?
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Re: Transferring waveforms from 54542a through GPIB
I do:
?
:WAV:SOUR CHAN#
?or :WAV:SOUR WMEM#
:WAV:POIN?
:WAV:XINC?
:WAV:XOR?
:WAV:XREF?
:WAV:YINC?
:WAV:YOR?
:WAV:YREF?
:WAV:DATA?
?
I loop through all channels and memory and if the channel or memory is not turned on the number of points will be 0 and I will skip it.? It does not trigger the scope and yes it returns unscaled points as a comma delimited ASCII string.? I then just parse the string and scale to get the correct time and voltage.
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Hope this helps.
?
Steve
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Probe Cables for 16801A Logic Analyser
Does anyone know the part numbers for the cables and probes for this analyser. I have some of the manuals but they dont say what cables to use, and no cables came with the unit when I purchased it
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Frank Mashockie
Rik Bos