"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
Жыл бұрын
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
Жыл бұрын
@@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
Жыл бұрын
@@antronargaiv3283 Same as on mine. But easy repair fortunately.
@Powertampa
Жыл бұрын
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.
@janosnagyj.9540
Жыл бұрын
Yeah, that hardware did cost you the same body parts back then 😅
@TeslaTales59
Жыл бұрын
And make you create an account just so you can use your own scanner!
@antronargaiv3283
Жыл бұрын
@@TeslaTales59 You just need an older one :-) MY Laserjet 5 don't need no steenkin' license!
@christopherleubner6633
Жыл бұрын
Back in the day this was about 5 grand.... in 1060's dollars.
@jagtan13
Жыл бұрын
@@christopherleubner6633 "1060" dollars. My goodness!
@OscarSommerbo
Жыл бұрын
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.
@SeanBZA
Жыл бұрын
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.
@itsverygreen532
Жыл бұрын
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.
@w9gb
Жыл бұрын
I use different dielectrics for Coaxial capacitors. Polyethylene or polypropylene tubing and aluminum rods/tubes make nice L-C traps for outdoor antennas.
@itsverygreen532
Жыл бұрын
@@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.
@CuriousMarc
Жыл бұрын
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!
@itsverygreen532
Жыл бұрын
@@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!
@gertebert
Жыл бұрын
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!!
@Chriva
Жыл бұрын
Same same :) Perfect timing every time lol
@anthonyparkinson3353
Жыл бұрын
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
@carpetbomberz
Жыл бұрын
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!
@cpufreak101
Жыл бұрын
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"
@chefchaudard3580
Жыл бұрын
I'm a retired EE. And RF was always kind of magic for me. So, we are on the same level here!
@glennstasse5698
Жыл бұрын
The only thing wrong with these episodes is there is no mystery. Marc ALWAYS figures it out and fixes the thing. Fabulous!
@dieSpinnt
Жыл бұрын
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:)
@glennstasse5698
Жыл бұрын
@@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!
@geraldhaggard1018
5 ай бұрын
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,....
@siberx4
Жыл бұрын
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!
@joe08867
Жыл бұрын
Very cool repair. HP sure knew what they were doing.
@CNe7532294
Жыл бұрын
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.
@DavePKW
Жыл бұрын
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.
@I967
Жыл бұрын
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!
@MatthiasWelwarsky
Жыл бұрын
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.
@PaulLoveless-Cincinnati
Жыл бұрын
Yay! I have NO idea what any of these instruments do but I am fascinated by the video documentation of their repair!
@mikefochtman7164
Жыл бұрын
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 :) )
@thesteelrodent1796
Жыл бұрын
at this point Marc seem to have just about every piece of kit from the 1960s and 1970s HP catalogues =D
@miscbits6399
Жыл бұрын
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)
@graemedavidson499
Жыл бұрын
Wonderful RF engineering where shape and form are function at these frequencies.
@like_cabezon3810
Жыл бұрын
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.
@like_cabezon3810
Жыл бұрын
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
@rigglestad8479
Жыл бұрын
[slaps top of retro HP equipment] 'this baby can fit so much physics'
@ThomasGabrielsen
Жыл бұрын
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!
@GordonjSmith1
Жыл бұрын
I loved working at HP, and I enjoy watching these videos almost as much! Simply wonderful.
@sefarkas0
Жыл бұрын
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.
@McTroyd
Жыл бұрын
A cavity search always makes for an interesting KZitem video! 🤪😅👍
@DrFrank-xj9bc
Жыл бұрын
RF Magic. Thank you for this beautiful Teardown.
@douro20
Жыл бұрын
I think you and Ken should try and design a K-band plugin- 18-26.5GHz, using some more modern components.
@PileOfEmptyTapes
Жыл бұрын
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.
@clytle374
Жыл бұрын
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.
@CuriousMarc
Жыл бұрын
Very cool. I wonder why I always get the terminally broken ones...
@clytle374
Жыл бұрын
@@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.
@RicoD5
Жыл бұрын
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 !!
@pr0engineer873
Жыл бұрын
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.
@13bigerdave
Жыл бұрын
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 😁😁😁
@tekvax01
Жыл бұрын
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!)
@TeardownOZ2CPU
8 ай бұрын
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.
@henryD9363
Жыл бұрын
Wow! And amazing. I must say I get nervous and anxious when you take these marvelous instruments apart. We can only admire and be humbled by the engineering genius it took to deal with these high frequencies 60 years ago. Wow!
@philiphighe1858
Жыл бұрын
I thought for sure that disassembly would be a one way journey, but no, how could i doubt your skills! Splendid and fascinating work and a great video. Thank you
@douggrove4686
Жыл бұрын
Looking at the characteristics of step recovery diodes, I have to wonder how this effect was even noticed in 1960. You would have to be looking at the switching characteristics of diodes with equipment that had a very high frequency response.
@ferrumignis
Жыл бұрын
The harmonics that it would have generated would have been very noticeable, but direct measurement of the super fast switching would have been quite difficult I suspect.
@christopherleubner6633
Жыл бұрын
Apparently they noticed that some zener diodes caused RF interference and they went from there.
@swedenfrommycam
Жыл бұрын
As always a pleasure 😀
@W6EL
Жыл бұрын
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!
@ReinierKleipool
Жыл бұрын
Amazing technology from the year I was born! Great work, Marc, on restoring this masterpiece.
@feicodeboer
Жыл бұрын
I wanted to call it magical first but actually those engineers were just geniuses.
@campbellmorrison8540
Жыл бұрын
As always wonderfully explanation thank you
@MarcelHuguenin
Жыл бұрын
As always a great video and I admire your RF knowledge and the way you film these adventures. They are very much enjoyable and educational as well. Thank you Marc!
@Chriva
Жыл бұрын
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.
@davidverbeek4849
Жыл бұрын
and goats. goats and virgin sacrifices, maybe even virgin goat sacrifices
@TheDigitalAura
Жыл бұрын
Such beautiful engineering. A work of art.
@ChrisR
Жыл бұрын
Those nixie tube displays have such an awesome look.
@SidneyCritic
Жыл бұрын
I suppose you could make a cone shim so the taper can seat on the bore, and that should locate it accurately before the tightening of the locking plate. If the gap is under 0.002" a paper cone might do.
@fgaviator
Жыл бұрын
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... 😂😊
@OscarSommerbo
Жыл бұрын
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.
@kaitlyn__L
Жыл бұрын
@@OscarSommerbo I love diode logic, and you can really see how they got from here to there.
@orbitingeyes2540
Жыл бұрын
RF gadget with a boiler in the middle of it! LMAO! Good one, Marc! Oooo, transmission line calculations... break out the Smith Charts!
@u.v.s.5583
Жыл бұрын
- Do not attempt to open! - Open or do not open, there is no attempt! We open!
@hymermobiler
Жыл бұрын
Another 30 mins of fascination thank you!
@nmccw3245
Жыл бұрын
“CAUTION: DO NOT ATTEMPT DISASSEMBLY OF CAVITY" - challenge accepted. 🥸👍🏻
@ronjohnson9690
Жыл бұрын
CuriousMarc wins again!
@genericdynamics6618
Жыл бұрын
The emoji cracked me up
@Chiavaccio
Жыл бұрын
👍👍👏
@williamsquires3070
Жыл бұрын
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!) 😅
@thehighwayman78
Жыл бұрын
Cavities are for filling, not disassembling... Ehm...
@buffplums
9 ай бұрын
I have one of these and also the plug in too. Mine was working last time I checked it. Must get it out and test it.
@jimmuehlberg2153
Жыл бұрын
Looking forward to the 8663 repair...love these things. I have 7 in the lab.
@michaelcox436
Жыл бұрын
Marc I'd watch you fix a toaster
@pilatomic
Жыл бұрын
I have one question left unanswered : What is the purpose of rotating the diode and the antenna assemblies ?
@SeanBZA
Жыл бұрын
Providing a matching function, so that your antennas are exactly, or at least closely, matching the changing angle of the resonant wave, as the cylinder changes in length electrically. Keeps the signal input, mixer input and output at close to maximum for the electrical coupling to be most effective. Not really noticed on a fixed cavity, as part of the tuning process involves adjusting the various antennas used for injection and extraction to a maximum level, and locking them at that point. However on a variable one you do need to adjust the antenna orientation to match, so the mechanism to adjust the angles, and the 2 RF boxes on them that provide short length connections to the antennas, minimising losses in that area.
@CuriousMarc
Жыл бұрын
It’s a puzzle to me. I first thought it was to maintain maximum coupling as the frequency changes, but it can’t be. The E-field is always normal to the wall of the cavity regardless of frequency, so it’s in effect varying the coupling coefficient. Maybe to equalize the response or the Q of the cavity over the band? I dunno.
@alanbain1651
Жыл бұрын
@@CuriousMarc In this plugin the cavity becomes electrically very short at the bottom end of the tuning range (around quarter wave long at 500MHz and it tunes down to 50MHz right). In the lambda/4 case it's fair to assume TEM propagation and solve as a transmission line but in the really short case I seem to recall the field starts to be significantly distorted by the capacitor. I assumed this is why there was a need to rotate the antennae for optimal coupling.
@CuriousMarc
Жыл бұрын
@@alanbain1651 That must be it! The TM modes will have an electric component along the propagation direction of the cavity, therefore you'd need to tilt your coupling antenna to couple efficiently into that propagation mode. I wonder if there is a gradual transition from one to the other, and you end up with a TE00 + TM01 combo. Would be fun to model this in HFSS if someone had access to it. I tell you, you better know your math and your Maxwell equations to do microwave engineering...
@christopherleubner6633
Жыл бұрын
Kind of have no choice but to disassemble the cavity to fix mechanical issues. You will want to take lots of pictures and keep a fine tip sharpie handy 😉
@fredflintstone8048
Жыл бұрын
Wonderful video of both the breakdown and explanation of function. Well done. I appreciate your efforts.
@624Dudley
Жыл бұрын
I’m always amazed by these fix ‘em videos. 👍 Plus, I feel like I’m learning something. Merci, Marc!
@alanbain1651
Жыл бұрын
I've repaired a good few of these but never dared go inside the cavity. Now I'm wondering if the 8640A/B signal generator cavity looks the same inside (with the addition of the little fine tuning flag)... At least these don't have plastic gears, wait for the 5254A/B/C; when they become sticky they strip the gear teeth. The gear with the dial attached has 61 teeth which is a most annoying prime number when it comes to cutting new ones. I seem to remember I had to get out the oxy-acetylene cutting torch and make a new diving plate!
@BFLmouse
Жыл бұрын
I remember having to deal with the same solidified grease while servicing HP 200 signal generators in the 1980s
@delwoodbarker
Жыл бұрын
"This set is equipped with a safety interlock. Do not attempt to defeat its purpose." I remember ignoring that all the time!
@mornax
Жыл бұрын
Superb series! Takes me back to an earlier life servicing equipment like this. Incidentally, I was watching a North Korea documentary and spotted an HP 5245 on the USS Pueblo (4:52 mark in this video: W_Z1oSINw-M) but it's missing the plugin module, nixies and knobs in other photos of it.
@andrewlecouteurbisson7217
Жыл бұрын
The yellow glass block looks exactly like zerodur ceramic.
@CuriousMarc
Жыл бұрын
Ah thanks, I was looking for the name of the thing and could not remember it. It certainly looked and felt like Zerodur indeed.
@andrewlecouteurbisson7217
Жыл бұрын
@@CuriousMarc I'm familiar with its use in ring laser gyroscopes. It definitely seems like a case of "no expense spared" in this application. That said, I was astonished by the accuracy of the down conversion so I presume it was money well spent!
@CuriousMarc
Жыл бұрын
@@andrewlecouteurbisson7217 Another poster mentioned Rexolite, but the large puck felt like glass, not plastic. However the rod looks suspiciously like plastic, so it might be Rexolite. I’d have to take another cavity apart and look closer!
@y2kkmac
Жыл бұрын
@@CuriousMarc it sure does remind me of Zerodur, but Zerodur was introduced in 1968, does that timeline track? Seems a bit late but what do I know... The mystery deepens!
@CuriousMarc
Жыл бұрын
@@y2kkmac No, 1968 would be too late. Then the Rexolite hypothesis is gaining even more traction! I'd have to reopen a cavity to know for sure.
@mm-hl7gh
Жыл бұрын
wow, 18gHz (!!) fun facts: at 18gHz the time between 2 steps is only 56 pikoseconds. in this short time, light travels only 1.6 centimeters (or 0.66 inch)
@randycarter2001
Жыл бұрын
The process of taking 2 frequencies and making 2 new frequencies, sum and difference is called HETERODYNING.
@VintageTechFan
Жыл бұрын
That (then) greenish grease is also horrible in 1930s--1960s cameras, the focusing thread is almost always stuck and you have to disassemble it using gentle heat, clean it, reassemble with fresh grease and then you have to find the infinity stop again ..
@Damien.D
Жыл бұрын
RF black magic, but with gears, and hand-cranked.
@TomFynn
Жыл бұрын
HP came out of a shed. And obviously, there were a lot of very sharp tools in that shed.
@CuriousMarc
Жыл бұрын
The shed is 10 minutes from where I live!
@kevinreardon2558
Жыл бұрын
Bloody amazing.
@netizen78
Жыл бұрын
The black magic of _The Cavity_ would make for a good legendary item in Diablo IV ...
@bprosman
Жыл бұрын
Looking at the disassembly and how you did it you must have owned some boxes of Meccano as a child 😂
@Rutherford_Inchworm_III
Жыл бұрын
"FOR THE LOVE OF GOD AND ALL THAT IS HOLY IN THE UNIVERSE, PLEASE DO NOT TRY TO SERVICE THIS UNIT." -handwritten sign on a big beige cabinet in the IT department of my college, c. 1994. It wasn't my department so I didn't ask.
@albing1397
Жыл бұрын
HP was awesome in the day.
@kaitlyn__L
Жыл бұрын
“How do they get a counter to work on higher frequencies just by plugging in a gadget?” Me, who has seen lots of SDR tutorials on frequency division or multiplication circuits to get the entire spectrum within the limited range of the hardware: oh I know this for once! Edit: well, I was still surprised by the _implementation,_ if not the theory! It's good to show how cost reduction from earlier optimal designs isn't a recent phenomenon at all. Thankfully the drawback didn't affect end use in this case, but it always starts by making repairs more perilous! I could easily imagine someone taking off those final screws back in the day and getting in trouble, especially if they'd seen earlier units with centring guides and weren't taking their time double-checking everything.
Why is there a video amplifier in there? Surely video amplifier is some sort of terminology I don’t understand.
@alanbain1651
Жыл бұрын
In this context it just means a broadband amplifier as opposed to a tuned amplifier.
@CuriousMarc
Жыл бұрын
I'm with you, it's very confusing historical naming. It's by contrast to an audio amplifier and a VHF/UHF amplifier. For wideband amplification to a few 100 MHz, it's called a video amplifier, even though it's not used for video at all! I suppose that was the first use such amplifiers at that frequency, so it stuck around.
@Monothefox
Жыл бұрын
These must have been SO expensive back in the day.
@thebiggerbyte5991
Жыл бұрын
Wonderful stuff!
@jlwilliams
Жыл бұрын
Not very relevant to this video, but: yesterday I met a 12-year-old girl named Nixie. I asked her if that were her full name or a shortened form of something else, and she said no, that's her full name. I said I had never met anyone named Nixie, but that there was a vacuum tube with that name, and she said "I know." Somebody out there is raising their daughter right...
@TheDiveO
Жыл бұрын
Does it have an ad block plugin at 666Mhz?
@marekkowalski6767
Жыл бұрын
Tnx,super hp Warsaw Poland.
@iNerdier
Жыл бұрын
If this is anything like cameras from the period (which I have worked on) the lubricants are biological rather than synthetic and they end up turning to glue…
@TeslaTales59
Жыл бұрын
* I just picked up an HP 3439A Voltmeter, then ordered the original service manual! I'll see if I can restore the beast...
@CuriousMarc
Жыл бұрын
Good luck for your repair! Go save it!
@Nico13531
Жыл бұрын
Great video. How do the rf wizards account for the stub resonator properties also changing significantly over the operating range? At 50 MHz you’re quite far from l/4. Does the q-factor drop for these frequencies?
@notmyname1094
Жыл бұрын
If you form extremely short pulses with that SRB diode of the 10 MHz: - are the short pulses like a gate or do they add high frequency portions to the 10 MHz ? - do you only get multiples (harmonics) of the 10 MHz with the short pulses and no other frequencies? - if yes: on digital signals: do (extremely) sharp/quick signal flanks "only" create multiples / harmonics of the frequencies that are already in the base signal?
@ms01rci
Ай бұрын
Apologies if the question has already been asked but can you please tell me where did you get the connectors you used for the extension cable that allows you to use the insert outside the counter? Perhaps a part number would help. Thank you so much for all the fantastic videos and documenting on your website, it's a wealth of knowledge!
@CuriousMarc
Ай бұрын
I am not sure where my extender came from. Mine says 5060-6033 REVA on the PCB, so it appears to be a genuine HP part. The green connector that's on it says TRW 251 15 30 261. I'm sure you can still find it new or get something close on eBay and make your own extender. Good luck in your restoration! Oh, you are asking about my plug-in extender? These are from my bin of parts, but they are standard connectors available from Digikey or Mouser in the US. Amphenol I think was the original brand? 50 pin connectors. You might also find them described as SCSI-1 connectors or telco 25 pairs pigtails connectors.
@soniclab-cnc
Жыл бұрын
the black art of rf voodoo
@ahmedgaafar5369
2 ай бұрын
Thank You Mark, great video as usual, one question Sir if you please, why the mixer assembly with the Comb gen. assembly rotates while we tune the cavity?
@CuriousMarc
2 ай бұрын
I believe this has to do with trying to follow the polarization of the electric field mode as the cavity tunes. It would be a quite complicated explanation so I left it out…
@materialsguy2002
Жыл бұрын
Marc, Regarding fabricating an extender: I went quickly through all the relevant plug-in schematics I have (nine or ten), and I could only find but 10 (out of 50) unused pins on the connector. The TI and Prescaler plug-ins used quite a few pins. Have you ever seen a universal HP extender? I wonder where HP put the coaxial leads? Thanks for the video.
@christopherbuckley7544
Жыл бұрын
Pretty Cool
@psy0rz
Жыл бұрын
Could you get away with soaking the whole bottom in IPA or something? to get it somewhat unstuck
@adrian_sp6def
Жыл бұрын
Is this down-conversion similar to wadley loop?
@briswolf
Жыл бұрын
Does anybody know why the drive and readout antennas are made to rotate as the cavity is tuned? That's really interesting. I wonder how accurate that part has to be. I imagine it is something like changing the length from the antenna to the nearest wall, if you draw a line perpendicular to the antennas ?
@TechGorilla1987
Жыл бұрын
@11:40 - In all fairness to HP and the vintage electronics, I would be averse to having a cavity search too. Just saying.
@thequinnreapernovaco.7497
Жыл бұрын
I just recently acquired a 5245L made in 1967. Works great, but some of the plug-ins I have could use some adjustments. Would you have the wiring diagram for your custom 50 pin plug-in extension cable? I’ve tried a few old 50 pin SCSI extension cables and while they physically fit, they do not pass the signals correctly. I must be missing something critical.
@CuriousMarc
Жыл бұрын
The only diagram I have is the one shown in the video. It’s all straight through, and the two coaxes at the end, as marked on the schematics.
@thequinnreapernovaco.7497
Жыл бұрын
@@CuriousMarc Excellent, thank you! And fantastic videos. They’ve inspired me to acquire a few of my own vintage HP counters and assorted gear.
@albertsandberg
Жыл бұрын
Wizardry on all levels
@radarmusen
Жыл бұрын
18:00 dr who’s sonic screwdriver.
@pizzablender
Жыл бұрын
I remember a poster in the sci.electronics who had a business selling comb generators. He claimed to use a very cheap and common part to do so, but (of course) wouldn't tell what part.
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