CuriousMarc - 2023-06-12
It's time to repair our 500 MHz frequency converter plugins, the HP 5253A and HP 5253B. It says in red letters: "CAUTION: DO NOT ATTEMPT DISASSEMBLY OF CAVITY". Really? Guess what we are going to do! 5245L Repair-a-thon Playlist: https://www.youtube.com/playlist?list=PL-_93BVApb5_MQBUOVLgdKCaUPY1zaPh_ Documentation on my website: https://www.curiousmarc.com/instruments/hp-5245l-nixie-counter#h.ixw2jz3t1jtb Stuff that supports the channel: - Amazon links for the tools I use in the lab (supports the channel if you buy from there) https://www.curiousmarc.com/amazon-links - Channel merch on Teespring: https://teespring.com/stores/curiousmarcs-store - Support us on Patreon: https://www.patreon.com/curiousmarc Our lovely sponsors - PCBWay: fast turn PCBs, https://www.pcbway.com - Electro-Rent: https://www.electrorent.com - Keysight: test instruments: https://www.keysight.com - Samtec: connectors: https://www.samtec.com - R&D Microwaves: https://rdmicrowaves.com Get more technical info on the companion site: https://www.curiousmarc.com Contact info: https://www.youtube.com/curiousmarc/about 00:00 Summary of previous episodes 01:00 The many plug ins for the HP 5245L 02:25 Making the extender cable 03:06 HP 5253 converter principle of operation (with elevator music) 07:58 Inspection and tryout of our first HP 5253A plugin 10:56 Summary of the first HP 5253B repair 11:27 Taking apart the second HP 5253A 14:02 Stuck gearing repair 15:37 Disassembling the "Do Not Disassemble" microwave cavity 19:13 Coaxial resonant cavity explanation (with elevator music) 23:05 Reassembling the cavity 26:19 Testing the repaired HP 5253A plugin 27:15 Comparing with the second HP 5253B cavity 28:26 Testing the second HP 5253B plugin
The "Do not tamper" warning makes total sense for the time period. HP had to carefully calibrate the units, and to assume that even government labs having the necessary equipment to carefully retune them would have been foolish. But I am sure they were disassembled and cleaned any way, just that HP took no responsibility for their accuracy after.
Cleaned and repaired at HP on every trip in for service, most likely by washing in chlorinated solvent to strip the grease, and then putting new grease on afterwards. Likely the original ones used whale oil as part of the lubricant, as it has superior properties over the common petroleum distillates used then. Thus the change to different greases and lubricants in the 1970's, when whaling was banned. One of the reasons you find 60 year old tape is perfectly fine and usable, but tapes that are under 50 years old need to be baked before use, and then you get exactly one chance to play it out, before the oxide layer falls off the backing plastic film.
With how HP or HPE operate today it's refreshing to see a piece of their hardware you can use without 30 licenses attached to it costing you an arm and a leg.
Yeah, that hardware did cost you the same body parts back then 😅
And make you create an account just so you can use your own scanner!
@@TeslaTales59 You just need an older one :-) MY Laserjet 5 don't need no steenkin' license!
Back in the day this was about 5 grand.... in 1060's dollars.
@@christopherleubner6633 "1060" dollars. My goodness!
The "perspex" material is actually called "Rexolite" and is more like solid polystyrene. Relatively low dielectric constant (usually around 2) and very low loss (tan-delta). It also has very low moisture absorbtion, commonly used in microwave applications.
I use different dielectrics for Coaxial capacitors.
Polyethylene or polypropylene tubing and aluminum rods/tubes make nice L-C traps for outdoor antennas.
@@w9gb Yep, at HF there are many suitable materials, I use commercial PVC pipe a lot for HF stuff, but in very high Q kit and professional microwave stuff, you often find Rexolite used. It has a very distinctive look and feel, once you've seen a lump and identified it, it's easy to spot. Commonly used in "dielguide" feeds on dishes, with an aluminium cassegrain reflector.
Another commenter suggested it could be Zerodur too (a glass material that has the very same look). I thought the same, but apparently it was introduced in 1968 which would be too late. I'd have to reopen it to be sure and test hardness, but Rexolite seems very likely. Thanks for the tip!
@@CuriousMarc Definitely not Zerodur ... that is a very heavy glass, commonly used for telescope mirrors, very difficult to drill and impossible to tap! Rexolite is much lighter. You will commonly find Rexolite used in HP stuff, they used it a lot for high voltage components. Once you recognise it, you'll suddenly reallise how much of it you have seen, widely used in military radar and RF stuff, RF coil formers etc.
Really enjoying the series, I have "a bit" of HP equipment, power meters, spectrum analysers, noise figure meters. My favourite piece is an analogue vector voltmeter. You should do a video on how HP made the scales individual to each meter, strange but true HP fact!
À bientôt!
I could not help to notice, as a tech (retired), that many pieces of tech equipment you've shown I used on telecom equipment. Brings back memories,....
I'm on the other side of the world (of CA that is) and Marc always manages to post his latest video during my lunch brake. Yay!!
Same same :) Perfect timing every time lol
3:30 I am not an EE, but I do think I "get something" out of these lessons on RF and even just basic Physics Eletro-magnetism fundamentals. 👍We don't need no teardowns of Apple Vision Pro.! No way man. Gimme a teardown of this sweet ol' analog HP 5245L freq. counter!
same, I'm nowhere near an engineer and I learn quite a lot from these videos. i'm also sure it's easier to learn with these older machines versus a modern device where it's just "traces go into proprietary box of black magic"
I'm a retired EE. And RF was always kind of magic for me.
So, we are on the same level here!
The only thing wrong with these episodes is there is no mystery. Marc ALWAYS figures it out and fixes the thing. Fabulous!
Hmmm, I think I spotted something very mysterious:
That you can't see the mystery or better the fascination of these old and wonderful designs and how explaining and fixing them comes all together to a big and consistent whole.
Just kidding...at your expense:P My apology! If you look from a slightly different angle, then there is enough mystery that is later revealed in a very entertaining and exciting manner:)
@@dieSpinnt no offense taken. I feel the same way as what you described. Everything here seems like black magic to me. It’s voodoo! It’s AI without the A!
Every time I watch your videos I instantly go to eBay even though I have modern test equipment these videos make me want old tech
I think that heterodyning is my favourite RF trick, and I've never seen a more beautiful implementation than these plug-in modules. Very cool!
It's a very satisfying process taking a mechanism apart, cleaning it, lubricating it and then putting it back together again. I always marvel at how something which didn't work properly or at all now functions smoothly, everything rotating and clicking. It's like magic.
Great job, well done. Thanks for the video, Marc!
Yay! I have NO idea what any of these instruments do but I am fascinated by the video documentation of their repair!
A cavity search always makes for an interesting YouTube video! 🤪😅👍
I absolutely loved this video. I am always so impressed at the technology of that period. And especially how both HP and Collins Radio implemented it so skillfully. Thank you very much for such a well done video.
Very cool repair. HP sure knew what they were doing.
Wonderful RF engineering where shape and form are function at these frequencies.
Can not imagine what it took to manufacture and calibrate in the 60s though I often hear that it can be good if not better than today's workmanship. What I do know is that aerospace funding had a massive boost in the late 1950s and early 60s. I wonder why lol. Great video as always.
Off topic, I have a 10590A which is not in use. Planned to get one of these oscillators to test it in. Came with my 5345A that runs a 5355A compatible with its 5356D attached. What I love about the 5345A isn't the fact that I can use my 11970W mixer to it but rather that it actually has someone's name (I'm assuming they did QC) inked on the display module when I repaired it. Simple faulty SCR on the a power module but decided to fully tear it down to rid of the dust bunnies. I took care not to remove any markings of any kind. These instruments were evidently made with care after all. To see the names and markings adds personality imho.
What a great job you are doing Marc! You explain what you do and how the equipment/apparatus you work with in an excellent way. I get very excited every time a new @CuriousMarc video is published. Why this channel doesn't have even more subscribers is a mystery to me. Thank you so much!
These levels of RF just boggle the mind. When you start dealing with 'cans' as coaxial lines, it just amazes me. And that you were able to disassemble and repair this is amazing. (not to mention you just 'happen to have' the signal generators to test this stuff :) )
at this point Marc seem to have just about every piece of kit from the 1960s and 1970s HP catalogues =D
Ah yes, the black arts of RF and resonate cavities! Another excellent repair Marc! *(...and you didn't even have to break out the Smith charts and protractors!)
I loved working at HP, and I enjoy watching these videos almost as much! Simply wonderful.
RF Magic. Thank you for this beautiful Teardown.
Ah yes, the SRD. The tool of choice for generating Gigahertz frequencies, in the 1960s and for at least two or three more decades. I have a rubidium clock source made by Datum Efratom in the late 1990s and the synthesizer generating the 6.8-odd GHz representing the hyperfine transition that is the atomic reference for the output frequency is basically using the same principle, a SRD comb generator and a resonant cavity to pick out the correct harmonic.
[slaps top of retro HP equipment] 'this baby can fit so much physics'
I think you and Ken should try and design a K-band plugin- 18-26.5GHz, using some more modern components.
“CAUTION: DO NOT ATTEMPT DISASSEMBLY OF CAVITY" - challenge accepted. 🥸👍🏻
CuriousMarc wins again!
The emoji cracked me up
👍👍👏
Yes, this is a dog whistle to every hardware hacker, hobbyist, and RF/Microwave aficionado out there to open it up. Because, who doesn’t like looking at some RF black magic; the darkest of dark arts (and we know this thanks to CuriousMarc’s Apollo series!) 😅
Cavities are for filling, not disassembling... Ehm...
As someone who arguably watches too many automotive repair channels - next time you are faced with gears coated in old grease and stuck screws, try recruiting your favorite penetrating oil (or at least WD40) and a quick trip to the oven (or perhaps just the outside, at this time of year in California). I imagine that should make disassembly a whole lot less stressful in such cases.
BTW, instead of just generating a frequency comb, you can also use such a pulse train to feed a sampling mixer that can than serve as the phase detector in a PLL. This way you can lock a continuously variable oscillator to a fixed frequency grid, you just need to limit the PLL VCO pulling range so that it can only do fine-tuning. This concept even briefly made an appearance in the consumer space by way of a few high-end FM tuners of the late '70s / early '80s. The point was combining the good frontend selectivity, linearity and low phase noise of a mechanically-tuned affair (not to mention lovely knob feel) with the accuracy and lack of drift of a PLL job. These concepts became redundant as people figured out how to make lower-noise PLL VCOs and gain distribution improved.
The first instances of oscillator grid-locking I could find even predate these HP units. The Siemens E311 communications receiver (1960) did this for its 1st LO, using funky electrically permeability-tuned inductors for fine-tuning no less - the varicap diode had yet to be invented, so tweaking inductance via core saturation was the next best thing.
I presume HP went with the "filtered comb" approach in order to keep size and complexity of this compact module down, alongside the large relative tuning range required.
Could you have used a lathe and dial test indicator to true the female part and then put the dial test indicator to achieve the same concentricity? All in all it's great that it worked out for you.
Later, frequency counters were equipped with a YIG-tuned filter that filters the incoming signal instead of the local oscillator (LO). Then, the filtered signal is sampled/mixed with a pulse of approximately several hundred megahertz. Also, manual power metering is done using the microcontroller to search for signals within the 1-18 GHz range. Very good video.
It seems that the newer HP counters like the 5342A didn´t had the YIG filter but other diferent models such as the EIP 545,548,585 and 588 have those tunnable filters
I used one of these in the 1980s in a HF transmitting station and used/rebuilt tunable cavity resonators on 100-500MHz landmobile kit during the same period (the Q on those cavities was so high that their bandwidth was less than 10kHz)
Reassembly of the cavity is highly sensitive to electrical continuity of all mating surfaces - there are large RF currents flowing on the internal cavity surfaces around the top end - right where your cap is. It matters more when hanging these after transmitters (heat losses) but it hugely affects Q if there is corrosion or poor conductivity across the surfaces. Those tarnished silver faces need cleaning (immersion in saltwater along with an aluminium strip will work best as it's a non-abrasive method - clean & dry thoroughly afterwards)
The robust design and warning are because these were intended to be used in military environments and army/airforce bois have a tendency to be rough on their equipment. Reassembly with the dial markings being correctly aligned is "difficult" (one of my ham-fisted cow-orkers pulled our one apart. It never worked properly afterwards)
It's amazing how clever and advanced engineers in the 60s already were! With all this witchcraft and rocket science they could have built spacecraft and flown to the moon... Oh, wait - they did... 😂😊
At the time, RF was the bleeding edge, and we are seeing the peak of RF trickery. Digital circuits rapidly overtook analog/RF tricks, with much more robust and rugged design. You can even see the beginning of the digital era in these instruments, all those discrete components, and no vacuum tubes. Well almost no vacuum tubes.
@@OscarSommerbo I love diode logic, and you can really see how they got from here to there.
you just saved me a million hrs figuring out how to repair mine, just scored the same counter 5245L and the same 500MHz plugin 5253B mine is also a bit stuck, I was going to figure it all out and explain it make a video about it, but now no need to add more bytes to the world of internet, since this video explain it all :-)
the funny thing is the 5245L main counter unit exist in several versions looking a bit different on the outside, now i got both versions, I also got one with 5267A plugin a time interval unit, that one is on my YT in case you like to see it.
OMG I don't understand much of anything about all the technical stuff yet am hooked on this channel and all the stuff they fix 😁😁😁
Fantastic! RF is a magic I will never fully comprehend. And it blows my mind even more they were able to master it to that level almost 70 years ago.
- Do not attempt to open!
- Open or do not open, there is no attempt! We open!
Did I just see something impossible proven to be possible? 😮 The accuracy of this 60’s magic is hard to believe. I’ll watch it a couple more times. And a warning to the other stuck plug-ins: Resistance is futile !!
EIGHTEEN gigahertz?
What kind of black magic grey beard wizardry did they use to build that in the 60's!? I bet it even involved virgin sacrifices.
and goats. goats and virgin sacrifices, maybe even virgin goat sacrifices
Thanks, awesome. Luckily my 5253B works, and thanks to your video I don't need to take it apart to see what Bill and Dave are hiding from me.
Very cool. I wonder why I always get the terminally broken ones...
@@CuriousMarc I normally buy the broken ones on purpose. But this one was luck in an auction. If it makes you feel any better the gears in my HP-8640B broke last week and I had to fix that. I spend most of my time on tube gear though.
RF gadget with a boiler in the middle of it! LMAO! Good one, Marc!
Oooo, transmission line calculations... break out the Smith Charts!
Another 30 mins of fascination thank you!
Wonderful video of both the breakdown and explanation of function. Well done. I appreciate your efforts.
I’m always amazed by these fix ‘em videos. 👍 Plus, I feel like I’m learning something. Merci, Marc!
As always wonderfully explanation thank you
As always a pleasure 😀
Those nixie tube displays have such an awesome look.
Amazing technology from the year I was born!
Great work, Marc, on restoring this masterpiece.
Such beautiful engineering. A work of art.
Looking forward to the 8663 repair...love these things. I have 7 in the lab.
Bloody amazing.
My HP-8640B has one of these adjustable cavities. Except… it has plastic gears in the knobs and they haven’t exactly aged well. Great video as always!
@lyrebirdcyclesmarkkelly9874 - 2023-06-12
"As Bill and Dave intended". "No resonant cavities were harmed during the filming" Both absolute gold.
I have HP equipment dating as far back as the 400C voltmeter. Love seeing your restorations / repairs.
@CuriousMarc - 2023-06-15
Ah, the famed HP 400 VTVM (Vacuum Tube Volt Meter) series! I have a 400E that I restored off camera, but the restoration of the HP 410C voltmeter restoration will be on video soon, promised! Mr. Carlson has a couple episodes on instruments from that series too.
@antronargaiv3283 - 2023-07-26
@@CuriousMarc I'm waiting for that 410C restoration. I was given one and I think one of the neon/photoresistor pairs is non-functional...there's an ominous "X" on one of them 😞
@CuriousMarc - 2023-07-26
@@antronargaiv3283 Same as on mine. But easy repair fortunately.