Unless you like VHDL...... <grin>
Harvey
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On 9/19/2024 5:29 PM, Dave Daniel wrote: 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)
==============================
On Sep 19, 2024, at 16:03, Roy Thistle via groups.io <roy.thistle@...> wrote:
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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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Argue that a master's degree looks like more highly educated employees.
I have a Master's degree in EE, and do software as well as hardware. I'd suggest taking courses in both.? Depending on what you want to do, Microprocessors and C++ (and possibly assembly, it could be argued) are good.? Python I don't really use, since it's easy enough to code in C++ (for me).? CAD?? Definitely if you want to do something with it, I could suggest looking at OpenSCAD as an interesting system.
C++ allows both processor and windows (and Linux, I'd say) applications.
You might want to see if you are going to be interested in either the system level programming (applications support) or applications.? All of the above are interesting.
Harvey
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On 9/19/2024 5:03 PM, Frank Mashockie wrote: 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
Look at that. The only issue I see is that the display is upside down. I guess you need to flip it over. Humor. By the looks of it you have some signal. But your IF BW may be narrow. Typically with a wider bandwidth you would see noise in the floor. Or its telling you gain is set low something silly like that. Front panel stuff. The 141T is a nice spectrum analyzer. It was the first one I used in the Navy circa 1975. Liked it a lot. But never owned one. Have newer units. Paul WB8TSL
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Re: Probing deep and/or narrow into a given unit for troubleshooting
I have done the tack-wires-on method many times too. A few nodes is easy to handle, with leads held safely with tape to keep from shorting. When there are lots, I usually use some kind of connector like a square pin header or plug at the ends to keep them all together and safer and organized. Then probe each with a test lead including a pin or socket that can stay connected if needed.
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I happen to have in my pile of test leads the longest grabber hook I've ever seen, and I'd think even longer might be available. I got it decades ago along with other junk, and never knew who made it until just looking now. This one is around five inches from the finger hold to tip, labelled "maxi grabber." I looked up that name, and it seems to be a Pomona product - you'll see all sorts of hits with that. I think this is their model 4225-2, where the "2" is probably the code for red.
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I've actually seldom used it except on bigger old-school circuitry. Even with longer reach, there are still the problems of manipulation to grab something, and visibility, so you'd still likely have to tack on some kind of node extensions to probe say in a card cage. It's also kind of fat, but good and strong - maybe there are skinnier, lower profile types too.
?
Ed
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Hi Adri, ? Yes, I am curious, you can send me a video on the intermittent noise problem, by going through OneDrive for example, or Dropbox. It could be that one of the PLLs is the cause. ? For the 8595E on which I was trying to repair, the problem was not on the 130 option as the error message seemed to indicate, but rather an incorrect alignment on the basic filters. The AMP CAL stopped because it was unable to find the two -3dB points of a filter. ? Yes, I realigned all the filters following the procedure in the service manual. There are 4 crystal filter sections and 4 LC filters. Simple procedure but a bit long, and you must not make any mistakes, otherwise you have to start from the beginning. I did the job slowly; everything went well and the original problem was solved. I recalibrated the instrument and took the opportunity to improve my software for flatness alignment, now after the test, all data is entered automatically...which speeds up the work. ? In my opinion, someone opened this 8595E to try to make a repair, the second converter had been opened, 2 screws were missing and 2 others were reset to 50%. I had to realign the second converter after closing it correctly. ? For the filter section, it is clear that one touched the adjustments, because half were well aligned, and for the others, the adjustments were very far from the optimal value. ? In total, 8 screws were missing on this instrument. Probably an interrupted repair¡ ? Yves ? ? hello Yves, great repair that of the opt 130
In my case the opt 130 has always worked well and I have never needed to study it in detail
Did you do the realignment by adjusting the trimmers on the board itself?
The adventure with my 8595E continues
To sum up, after my last email I focused on a more accurate and uniform alignment of the SYTF. With the help of the microscope, a strong light source, a precision power supply and a fairly reliable frequency source I obtained an insertion loss as per the attached excel file
After reassembling the RF front-end everything worked fine again, including the MXR CAL routine that?used to?give the?error? "insufficient harmonics"
When I moved from the "messy" version (pic)? reinserting everything into its space (which is very crowded, also due to the existence, in my case, of the tracking gen)?and connected?the SA input to CAL OUT I observed a type of intermittent noise, in the form of spikes of intensity about -60dBm that appear and disappear in the area of ??the highest harmonics (I already checked the?CAL OUT signal; it?is clean and fine)
Now I think I will have to re-disassemble the front-end (ouch) and try to understand from where does this noise originate :-(? If you are interested I?can send you a short video of the problem (don't think I?can post videos here)
Thanks for asking, Yves
Adri
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I agree with you completely. Over 50 awesome messages and a wealth of ideas. I also liked seeing the LED "mood" lighting and the flat screen monitors incorporated into some benches
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Jim
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Re: HPIB disk drive as a substitute for SRAM cards
Hi
?
I'm not sure which driver you may be referring to so you might have to explain further.
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I did not format the card. It was borrowed and came with the attenuator cal files on it. It will be mailed back soon.
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The HP museum is great! It was of help with my earlier efforts to get the dual disk drive talking to the 8924C.
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I did download MCE for my old Dell LapTop running on XP.? I was getting nowhere with MCE plus I didn't want to risk screwing up the card I borrowed.
It was very generous of those folks to trust me with it.
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I'll send you an email.
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Thanks!
?
Jim
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Re: HP 141T Power Supply Help Needed
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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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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.?
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What are some creative and crafty solutions others have found useful? Maybe some miraculous tools you've found??
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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) ==============================
toggle quoted message
Show quoted text
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.
?
?
?
|
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.
?
?
?
|
Frank Mashockie
