Vintage Hewlett Packard Test Equipment Extravaganza

[@CuriousMarc]

David, I have also a 608D in the restoration queue. Should we do it at the same time and have Mr. Carlson on speed dial? BTW the 608 was part of the original RF lineup that started the incredible HP RF instrument line, with specs so awesome that it stayed one the catalog forever. I just checked, the 608D is in my 1965 catalog (the oldest I have), and the 608E still appears in the 1981 catalog! The 608A was introduced in 1950. A 30 year run.

[@_f355]

great to see you here Marc! a collab would be awesome, David's channel could really use more subs :)

[@AlienLogic775]

A trio collab with the best (Marc, Usagi and Mr. Carlson) would be a dream! Thanks for all the joy you all provide to us.

[@charliepanek8481]

Mr. Carlson also recently did a video about a 521C he has. His was in really good shape (and working), not sure it even needs any restoration. (Where does he find this stuff?)

[@jeldrikpetersen]

How awesome could this get! Please include a detail dissection and some CuriousMarc analysis of this black magic RF box!

[@VandalIO]

Woah ! This will be epic three musketeers restoring stuff together

[@michaelmiller641]

I love all this old technical equipment, especially as it uses valves,/tubes!

[@UsagiElectric]

HP's equipment is all pretty spectacular, but their old tube stuff is really amazing stuff! I love digging through and trying to figure out just how it all works!

[@tomschmidt381]

Wow seeing the 608 what a flashback. I was an avionics tech in the military during the late 60's and used it extensively repairing UHF aircraft radios. I've never seen the inside as ours never failed while I was assigned to H&MS. The other stuff on the radio bench was a TS505 VTVM, and a RF and audio watt meters, forget the military designation of those pieces of test equipment.

[@UsagiElectric]

That's awesome that you got to work with the 608D in it's intended environment! It's good to hear that the one you used never failed, that bodes well for this one getting up and going again! Also, that TS505 VTVM is excellent, it looks like it was built to survive just about anything, haha.

[@deadlinkofficialartst5592]

That HP 211A Square Wave Generator as a Test Equipment to me is a music instrument aka synthesizer

[@UsagiElectric]

It combined with the 200CD could make some excellent synthy sounds! I actually do plan on making a big DIY tube synthesizer this year as a bit of a long term project!

[@deadlinkofficialartst5592]

@@UsagiElectric Nice

[@kevinsmith3854]

I say collaboration with CuriousMarc on the 608D with input from Mr Carlson would be great

[@thomashowe855]

Agreed

[@UsagiElectric]

I'm with you on this one! The 608D will go straight to the top of the queue if it means I get to chat cool old HP stuff with Marc!

[@lost4468yt]

For some reason KZbin loves your channel at the minute. I've been suggested like 20 of your videos over the past few weeks.

[@UsagiElectric]

I mean, that sounds like excellent news to me!

[@DrGerryD]

LOL, Way back I was trained in the Army as an electronic test equipment repairman, I had the MOS of 35B20 and 35B30. My ETS was in 1972, After the service I worked at an army depot in their instrument shop and repaired a large variety of HP test equipment. I remember working on nearly all that you show. But mostly the HP400 AC Voltmeter and the HP410B Multi-meter. I would have three or four HP400's burning in while I was going through the specifications on another for the QC inspector. Fun times.

[@gammaleader96]

The build quality of these old HP devices is just increadible. I love the high amount of mechanical stuff in them, this was just a completely different approach at problems. I can't even (and don't want even) decide on which one you should do first, they all have some very interesting topics to cover and I look forward to every single one of them.

[@UsagiElectric]

HP built some amazing stuff didn't they! The 412A DC VTVM is really interesting actually, the Synchron is an AC motor that spins a wheel to make or break light from the bulbs contacting photosensors to make a chopper circuit for modulation and demodulation. It's a beautiful collection of mechanical and electrical engineering!

[@gammaleader96]

@@UsagiElectric Oh well now I know what else I wanted to comment. As you already figured out, the synchrotron is a very early chopper amp. Mr Carlson also has an old video of a RF voltmeter wirh a little neon bulb photocell chopper like this.

[@EsotericArctos]

With regards to the Selenium Rectifier, they don't need wholesale replacing the way some internet people may portray. The tend to slowly degrade over time, not just suddenly melt down (unless the rest of the circuit shorts out). The slow degradation results in increasing voltage drop, and this causes increased heat over time and when they start running hot enough they may fail. If the voltage drop is within specs, they are quite safe to continue using. They may just need checking occasionally. It's personal choice, but don't feel that the Selenium devices are the big ticking bomb some people make them out to be.

[@winstonsmith478]

You're in the early stages of "Mr. Carlson's Addiction" (MCA). I vote for restoring what you could use the most first.

[@UsagiElectric]

MCA with a little CuriousMarc flair! Honestly, I never intended to become an HP test equipment aficionado, but once I got the 150A I got the bug and now I'm always on the hunt for more vintage tube HP gear!

[@winstonsmith478]

@@UsagiElectric Yes, it's great to see the innards of beautifully engineered hardware where cost was no object. Accuracy and reliability was.

[@alanpecherer5705]

At a garage sale I bot a 711A power supply and a 521A counter for $25. The 711A was a little flaky but came right back to life and reasonable calibration after simply replacing all the bumble bee .1 uf caps with new ones. You just have to rip those out and replace them, they are always all bad. The 521A counter worked fine as it was. I unfortunately lost it in a fire, but I still have the power supply. I also built a little box using a backwards filament transformer that runs off the front panel 6.3 + 6.3 volt AC posts. The box runs a filament xfrmr backwards and produces enough volts to run an 0B2 105 volt gas tube and produces a 0 > -90 volt variable bias supply, the lack of which is a serious shortcoming of the 711A supply. Kewl piece of gear. The AC and DC VTVMs you have use a chopper and light interruptor mechanism to measure volts, and are kind of arcane. They are probably pretty tricky to troubleshoot. You will like the 211 sq wave generator (and it uses several 6CL6 which you thot you might use in your 6AU6 computer project) That piece can put out a VERY strong square wave, 50-60 volts.

[@kurtfrancis4621]

Damn, those are FINE looking pieces of equipment. Reminds me of century-old Cincinnati milling machines that are maintained. May these scopes be kept running until at least 2100.

[@zaprodk]

The "synchron" is a synchronous motor. My best guess it's an interruptor for a chopper amp.

[@UsagiElectric]

You absolutely nailed it! I dug through the manual after I posted the video and that's exactly what it's used for!

[@AccidentalScience]

OMG that sine wave generator! It's the same model that was in the laboratory when I was at high school! Soooo many yrs ago !

[@UsagiElectric]

The 200CD is one of the best sine wave generators ever built! I think every lab for like 30 years had one hiding in there somewhere, haha.

[@larrybl]

Mr. Carlson would like the VHF signal generator.

[@UsagiElectric]

The person I got this 608D from had another one identical to it sitting right next to it! Getting it is easy, getting from Texas to Canada is a whole different battle!

[@senilyDeluxe]

24:00 3rd tube from the left also looks like it went to air.

[@UsagiElectric]

Good eye! I actually thought the same thing, but that tube actually has the getter on the side that's pointing down and it still looks good!

[@jeffreyyoung4104]

I grew up with HP equipment, and even today, I still have and use them on occasion! There is somethings in life that survive the newest, and what I was going to say, is now, no longer the newest, Fluke meters has replaced. But I am sure there is a replacement for Fluke soon, just as the HP and Simpson meters have lost their glossy newness, Fluke meters shall also get tarnished, but as I am no longer in the mainstream of electronics, and only work from my home, things will pass me by...

[@blackarrow8683]

The HP521A gets my vote! 🥰

[@UsagiElectric]

Thanks for checking out the video and your vote! I'm keeping an Excel sheet with a running tally to see which piece is the most popular!

[@andyfinlay9776]

HP made some superbly well engineered tube powered test equipment, didn't they? I'd do the DC VTVM, followed by the AC one and then the 521A frequency counter because 'use vintage test gear to repair other vintage test gear!'

[@UsagiElectric]

HP never ceases to amaze me with their engineering! Thanks for the vote on the equipment, I'm keeping an Excel sheet to see which pieces get the most votes!

[@larsord9139]

@@UsagiElectric And they started in a garage with an audio generator (300 I believe).

[@kuzadupa185]

The age old question... what test equipment does one use... to test broken test equipment???

[@frankhenigman5117]

If the meters use the same meter, maybe you can get measurements off the intact one to help recreate the bezel and scale. I'm most interested in the frequency counter, but as others have said it would be cool to do the meters first then use them on the other gear. Your charisma, Mr. Carlson's know-how, CuriousMarc's HP love - that's a dream team. 🙂

[@UsagiElectric]

Unfortunately, the AC and DC meters are just different enough that I can copy it over verbatim, but they do share enough similarities that the AC meter will make a great template! One of these days, when travel is okay again, I'll have to try to talk my way into flying out to visit CuriousMarc's HP collection!

[@teslakovalaborator]

I suggest working first on the VTVM, as you can repair the rest of the equipment using the HP VTVM and scope.

[@MrSlehofer]

Agreed, also Zdar :)

[@UsagiElectric]

Thanks, and that's an excellent idea!

[@tstahlfsu]

Do the counter! Paul over at Mr Carlsons Lab just did, but I'd love to see your take on it!

[@UsagiElectric]

I'm really excited about the counter. It's got a brilliant mix of analog and digital design going on inside that I'd love to do a deep dive on while restoring it!

[@stphinkle]

I would go for the frequency counter. Tube digital circuits are interesting

[@UsagiElectric]

I'm right there with you, all tube digital circuits are just amazing! Thanks for the vote on the equipment, I'm keeping an Excel sheet to see which pieces get the most votes!

[@TheBananaPlug]

I was going to comment that you are becoming the CuriousMarc of older HP stuff, and then lo, a comment form the man himself. Truly if you want a challenge then the 608 is my choice, I had one when I lived in the UK, and it was used to retune old PYE RF equipment to the amateur VHF bands, sadly it was destroyed by an inept moving company in one of my overseas moves. Good luck if you do choose to go with the 608 first.

[@UsagiElectric]

The 608D is going straight to the top of queue if it means I get to chat VHF and RF stuff with Marc! That's a shame that yours was destroyed in a move, it's always sad to see one of those old pieces of equipment die. Fortunately, the 608 it seems was made for like 30 years, so there should still be quite a few out there!

[@aksela6912]

Pareidolia is definitely doing its thing here, because I'm seeing so many funny faces ein these instruments! The 608D would be fun, but maybe not the best start? One approach would be to think about which ones would be useful when trouble-shooting the others? The 711A power supply that needs some body work would be my vote.

[@UsagiElectric]

Haha, I never thought about that, but you're right, there are some funny faces hiding in there! The 608D is definitely a difficult one. I'm not even sure how I would go about testing it to make sure it's working. It's slowest oscillation speed is faster than the fastest speed the HP 150A scope can support. I can always break out the modern Siglent, but that's not quite as fun as using vintage HP stuff to restore vintage HP stuff. The 711A is probably the one I would get the most immediate use out of though, so that's a good vote!

[@glufke]

I’ve never seen any equipment without a board. Impressive!

[@UsagiElectric]

PCBs were really just coming into their own in the 50s, so a lot of stuff from that era is often point to point wiring or uses turret boards. I love that HP was really experimenting with designing stuff on PCBs and using a mixture of all construction styles. It shows they weren't beholden to a specific type of engineering and they made some really excellent stuff as a result!

[@byterock]

An arc-cricket is what the old teks use to call this. Depending on the volume/pitch you can tell it is internal or external. Low volume high pitch. internal in your case. Glad to see the Se rectifier gone. Btw you should always install your coupling caps with the foil-side to ground ;) For example the strip on the old type 33 I bet that was pointing toward ground.

[@UsagiElectric]

An arc-cricket - I like that! I've heard a lot of differing opinions on the foil side to ground for the caps, but it requires some special testing to figure out which side is foil side on the new modern caps I buy, and I'm way too lazy for that, haha. Fortunately, the HP 150A didn't seem to care because it came right into spec according to the manual!

[@byterock]

@@UsagiElectric It is the low frequency range that will be most effected. But if you happy I am happy. Checking for the foil side is easy, all you need is an old guitar amp and a little time. I myself use Mr Carlson's little device, and I only ever use it when I get a batch of new caps in and check and mark each one, On the Se rectifier side of things supposedly at low voltage the will last forever, it is higher voltage and bad caps that will cause the big smoke with them. I myself just bypass them as why take the risk.

[@UpLateGeek]

I'd say go for anything that you can put to use sooner rather than later. Obviously if it's higher up on the difficulty scale you might want to push it down the list further, till you get more practice on some of the other units. But that 608D signal generator looks amazing, so it would be pretty cool if you and CuriousMarc could get yours and his working at the same time.

[@UsagiElectric]

Thanks! Honestly, for most of the stuff I build, the 200CD signal generator and 150A scope are plenty. Occasionally I need a square wave rather than sine wave, but the 150A actually has a square wave generator built into it (the calibrator). Other than that, on the very rare occasion I need some HV, so the PSU could be useful, but then again, the VTVMs would definitely get use too if they were up and going. But, I'd shuffle the 608D right to the start of the queue if it meant getting to chat with Marc about VHF stuff!

[@mr.salisbury2435]

Per numerous Mr Carlson test equipment videos the red Spragues are di film and are very robust

[@UsagiElectric]

Thanks for the heads up on the caps!

[@CraigHollabaugh]

I'm experiencing a lot of 711A envy right now. Thanks for the video.

[@fullwaverecked]

Hey Craig! I'm with you.

[@UsagiElectric]

That HV PSU is so cool, and it's so clean inside that I think it'll probably really only need heavy work on the bezel! Thanks for checking the video out!

[@transientaardvark6231]

Does anyone here have any ideas how I can find a good home for a dual beam valve scope in the UK ? (Also many vintage CRT monitors and serial terminals).

[@edgeeffect]

Where in the UK? "Serial terminals".... this, I am liking.

[@transientaardvark6231]

@@edgeeffect Well, I assume that YT will block any attempt at sharing contact details, so how about I could deliver them to any ex-equipment shop / second hand shop etc that was reasonably close to the middlish part of either the A1 or the M1. To be clear they are very old very bulky CRT dirty scrap serial terminals. They haven't been powered up in decades (I would at least check they "work" before transporting them anywhere). Microcolour Graphics models M4305 & M2100. (and the scope is a Solartron CD 1440)

[@cpucat]

I love how hp went from being known for scientific equipment to being known for suboptimal prebuilt computers

[@RWBHere]

You shouldn't really need to replace those Selenium rectifiers. Unless they've been abused they will last for a lifetime. Equipment was often designed around their relatively high voltage drop (compared to Silicon rectifiers) and internal resistance, so that needs to be taken into account if you need to replace them, in order to avoid supply voltages being out of spec.

[@TeslaTales59]

Excellent repair sir! Be careful with those volts! - I vote for any of the vintage HP's to be prettied up.

[@UsagiElectric]

Thank you so much! I was definitely making sure to keep one hand in the pocket while playing around with the case open, 5kV is a lot of voltage any way you look at it!

[@christophervillanti1417]

The red print spragues are di-film and should be fine.

[@UsagiElectric]

Thanks for the info on the caps! I'm terrible at identifying caps, but any that I don't have to replace is excellent news in my book!

[@mansnilsson4382]

There's a 428B missing! :-) Iconic device. The perfect amp bias tool. Mine is accompanied by 410B and 400H, as well as 3552A and 3438A, for Nixies I've got 5221A and then there's Junior, a 974A.

[@UsagiElectric]

Oooh, the milliammeter! That one is on the list of ones to get! I don't due much amp biasing, but having a milliammeter in the suite feels like a must at this point, haha. Also, the 410B is an amazing little VTVM. The probe with the tube in it is just so cool. You have an absolutely lovely HP collection too it sounds!

[@SeanBZA]

Old capacitors try using something to generate 4kV or so, and then applying some voltage to each one, with a series 10k resistor, and a small 600R speaker to hear the breakdown as the capacitors break down. You will find which have failed from the clicking.

[@UsagiElectric]

That's actually a really cool idea! Unfortunately, all the old 6kV caps are already in the bin, haha.

[@SeanBZA]

@@UsagiElectric I used to test motor run capacitors by applying 1kV to them, and listening to the crackling coming from inside them. Old capacitors will break down, but the new ones will survive 1kV from an insulation tester no problem. first test for breakdown, then discharge with a 68k 10W resistor for a few seconds, then leave for a few minutes, then short them (dielectric absorbtion) and check capacitance, normally down to under 70% of nominal value. Crackle means change anyway, it is done.

[@AlejandroLopez-qd3xm]

Sweet stack of HP candies! You better start buying those caps by the hundreds, in order to make those old ladies reliable.

[@UsagiElectric]

Thank you! Fortunately, Mouser is located only a few hours North of where I live, which means they can often deliver a bunch of caps in just two days. When I was working on the 150A, I think I was getting a Mouser order every other day for like two weeks, haha.

[@regenceaudio]

Please post more videos of vintage HP test equipment repairs!

[@lelandclayton5462]

You used heat shrink for the rectifier but didn't add any sleeving on the long leads you added to the caps in the high voltage box. The sprague caps with red writing are diefilm caps so they should be just fine. Also the Selenium rectifiers only go bad when they have been stressed for a while due to over current use. It's a 50/50 shot but typically they just don't go up in smoke unless something caused it such as running the device with bad filter caps causing a excessive current overload. I would work on the VTVMs first so you can use them to troubleshoot the rest of that equipment.

[@UsagiElectric]

The heat shrink tubing on the rectifier was to prevent a short due to the close proximity of the wires. However, for the caps in the HV box, those all had pretty long, exposed leads originally, and there weren't any places that seemed to have anything too close that could cause arcing or shorts, so I didn't think it was necessary. So far, it all seems to working well! Thanks for the heads up on the Sprague caps, I'm terrible at identifying old caps. As for the Selenium rectifiers, I've heard that they can start to degrade and increase in internal resistance, even under normal operating conditions. The smaller ones in the other equipment are probably fine, but the big in the HP 150A was part of a series heater circuit, so it definitely saw quite a heavy load for most of its life. Thanks for the vote for the VTVMs! I'm keeping an Excel sheet with a running tally to see which piece is the most popular!

[@RenovatioSolutions]

Use something like JBweld to fix the corner , would love to see the resto on the frequency counter

[@UsagiElectric]

That frequency counter is so cool, isn't it! I think for the power supply, I'll ultimately use some JB weld to hold in a metal frame work, and then build up the rest with automotive body filler so I can sand it to a smooth finish and then paint it.

[@SeanBZA]

Yes just put a wire brace inside the plastic, then build up and shape it to match. Then paint the whole bezel to get it to match.

[@hestheMaster]

The frequency counter.

[@UsagiElectric]

Thanks for the vote! I'm keeping an Excel sheet with a running tally to see which piece is the most popular!

[@harryshector]

I vote for the 608. I spent a lot of time inside those in my salad days. You're in for a treat... They are marvelous generators, but they can drive you nuts when they don't work properly.

[@UsagiElectric]

I know so little about the 608, it's going to be a really interesting piece to dive into and learn about! Fortunately, HP made some pretty fantastic manuals, so hopefully I can get it back up and running again soon!

[@jeldrikpetersen]

Definitely you should go for the 412A VTVM first, followed by the 400H. Then you can use the tube Voltmeters for restauration of their tube buddys 🤔

[@UsagiElectric]

Ooh, I quite like that idea! Using vintage test equipment to repair vintage test equipment!

[@georgegonzalez2476]

Useful note: See those tubular capacitors where one lead is much fatter at the base than the other? Ever wonder what that is about? As it turns out, that bulge is a thin brass tube which was used to fill the capacitor with oil. Then a wire was soldered into the tube. Clever. However you would always end up with a little bit of flux going into the capacitor oil. Eventually the flux would contaminate the oil and lead to internal leakage. Also those black tubular caps with yellow lettering were often paper dielectric capacitors which also tend to go leaky over the decades. If the lettering is reddish-orange, people say that the caps have a plastic dielectric and they tend to be a bit, but not a lot less leaky. Both HP and Tektroniks used both styles of black tubulars. I always replace all of them, even the ones that only show like 100+ megohms of leakage. Regards, George

[@UsagiElectric]

That's really cool, I was curious about the fatter base at one end, but I never would have guessed it was to fill the cap with oil! That's awesome! I mean, break down and internal leakage isn't that awesome, but still, I love seeing unique construction techniques like this! Thanks for the insight on the caps, it seems that lot of people are saying the Spragues with the red lettering and the yellow caps should be totally alright. That's good news in my book because it's fewer things that I have to replace!

[@lindoran]

I'm excited to see whatever you work on but if I had to pick it would be the decade counter for sure.

[@UsagiElectric]

Thanks! I'm definitely excited about that one for sure!

[@thomashowe855]

On the 211a, those sprague caps should be good. The red color means they are film.

[@UsagiElectric]

Thank you for the heads up! I'm so terrible at recognizing old caps, but it's good to hear that those don't need replacing, that makes my life a lot easier!

[@thomashowe855]

@@UsagiElectric actually, I’m not entirely sure. Try to leakage test them.

[@ThePapa41]

Hi, you might try using the scale from the DC VTVM and add the needed graduations for the AC meter.Lou

[@KeritechElectronics]

Start with 711A, then 211A. By the way, that Vault Boy tee gives you +1 to Charisma :)

[@UsagiElectric]

Funny story about the Vault Boy tee, I totally forgot I wasn't in an Usagi Electric shirt when I filmed that bit. Then during editing I realized and said "If it were any other tee, I'd be tempted to reshoot, but Vault Boy gets a pass!" Thanks for the vote!

[@edgeeffect]

A white getter isn't SO bad... time for a tear-down. :) Ooh! I want to smell a selenium rectifier gone bad now!

[@kennye6088]

You will at lease need a 5-7 watt resistor, 1-3 watt will heat up.

[@UsagiElectric]

I think you're referring to a resistor for the heater rail in which I replaced the selenium rectifier? If so, I actually didn't need an additional resistor, the variable resistor that was already in place (R1323) has enough adjustment in it to bring the DC voltage right into spec. according to the manual. Also, that variable resistor is a 4W resistor, so you're right that 1-3W would definitely be undersized!

[@aldoali6173]

great, and the best part is the outro!!!

[@UsagiElectric]

Thank you! That's Kono, she was our first bun when we were still living in Japan. We miss her dearly, but she brought us many years of pure joy!

[@aldoali6173]

​Kono is just like the Logo Bunny

[@blenderbuch]

Blinkenlights! Frequency counter 🥳

[@UsagiElectric]

Thanks for the vote! I'm keeping an Excel sheet with a running tally to see which piece is the most popular!

[@kupa7217]

I think the 412A and 412H would be good small projects to start with

[@UsagiElectric]

Thanks for the suggestion! The two VTVMs are definitely an excellent starting point as they would both prove very useful for restoring the rest of the equipment too!

[@willynebula6193]

I say frequency counter 1st. But hey, it doesn't matter. Because ill watch all of them getting repaired and restored!

[@UsagiElectric]

Thanks! I am indeed quite excited about the frequency counter, but I'm keeping a running tally of everyone's vote to see which one was the most popular!

[@InssiAjaton]

To me the yellow capacitors looked like polyester type and therefore not my first candidate for replacement. The round "funny thing" looks like a synchronous motor. I would expect to find a light chopper wheel behind the panel. In the old vacuum tube era it was quite hard to make stable DC amplifiers, so a chopper -> AC amplifier -> synchronized rectifier -> DC output stage was the way you find on old HP meters. A synchronous motor would likely provide lock to line frequency and therefore hum canceling. As to the DC power supply, I think it would be linear type, series pass. If the raw supply is over 500 V, at the 0 output and 100 mA current, the series pass element (tube) would need to dissipate 50 W. Going up to 500 V, the tube dissipation is reduced to near zero. So, contrary to your suspicion, the unit would have no trouble producing 100 mA at 500 V. That of course assuming the tube(s) are not "weak" and still have good cathode emission. Anyway, my vote for an early ichoice to go through the fixing process is the power supply.

[@UsagiElectric]

Thanks for the insight on the capacitors! I'm terrible at identifying old capacitors. It seems the yellow caps and the Sprague caps with red lettering are actually alright to leave in for now, which is excellent news. And good call on the synchronous motor! You're absolutely right that it's a chopper for a modulator - demodulator setup it seems. I'm still fuzzy on how or why that's needed in the DC multimeter, but that's why I've got it - to learn all sorts of new things! Also, thanks for the info on the PSU, that actually makes total sense. It's opposite to how I was thinking, but you're absolutely right!

[@harisalic2568]

After watching so much tube content I just had to get me some tube equipment. Sadly the HP stuff is pretty expensive but east Germany doesn't dissapoint with a good selection of soviet made tube oscilloscopes

[@itsallaboutASL]

412a. I’m very curious to see the restoration on the lot!

[@CraigHollabaugh]

Hey UE, One of those HP711s just sold on eBay for about $400. Probably one your viewers snatched it up.

[@UsagiElectric]

Whoa, that's actually gone up a bit! I got mine on eBay too, but it was for under $300, though the broken bezel may have been helping to keep the price down.

[@getbentaudio585]

I have a distortion analizar, and a super old hp tube tester. I wanted to restore the tube tester, but im afraid of ruining an antique.

[@UsagiElectric]

I like to think that these old pieces of equipment were meant to be used, so even if some of the pieces inside need to be replaced, it's worth it to see them come back to life! Also, HP's vintage tube test equipment is still fantastic even today. For most of the stuff I build and play with, the HP equipment is actually overkill!

[@mattisafur]

I think you should start with one of the units in the worst condition, and if/when it needs a long procedure to continue on it or you start to feel a bit of a burn out from working on it, work on one which will take you a shorter time. as you said, some of them take a skill set much different to the other some of which you'll need to learn from 0. so I think you'll enjoy taking a break from each subject sometime (I know I would).

[@UsagiElectric]

I tend to do this already actually! Though, it's on a bit of a different scale. The HP stuff is a bit of a distraction from the vacuum tube computer to keep me from getting burned out on such a long project. Interestingly, none of these seem like they'll really need heavy diagnosing like the HP 150A did, or at least, that's what I'm hoping, haha.

[@odinthorson5751]

The Hp400H gets my vote! 😃

[@UsagiElectric]

Thanks! I'm keeping an Excel sheet with a running tally to see which piece is the most popular!

[@JenkinsUSA]

Nicely done!!!

[@Renville80]

Can't recall his name, but I understand there is a major collector of vintage HP gear down south.

[@robnic52]

I'd like to see the frequency counter with four neon column displays.

[@UsagiElectric]

Thanks! The frequency counter is super cool. There's a lot of really interesting mixtures of digital and analog design going on inside of it that I would love to do a deeper dive on as well!

[@VandalIO]

Hahah it feels like your setting up 1960s hybrid electronic lab

[@UsagiElectric]

The goal is to have a full suite of pure tube electronic test equipment!

[@jamesnorman415]

Watching my 3 favorite electronics channels is fun and a little depressing because I used a lot of this equipment in my college years. 🙃 p.s. love the rabbit!

[@UsagiElectric]

Thank you so much! And there's nothing depressing about having gotten to use this equipment in your college years, that's awesome! The rabbit says hi :D (Well, she really just ate some snacks, but I imagined that as her saying hi, haha)

[@mr.salisbury2435]

Suggest you make a dim bulb tester before plugging any of the stuff in

[@mr.salisbury2435]

Very easy with a bulb holder from hardware shop (low dollar) -I used an appliance bulb first of all but got a couple of higher wattage traffic light bulbs of eBay which survive bench abuse better. I would also highly recommend an isolation transformer and variac. Burning out a choke or transformer on this beautiful gear would ruin your day. The isolation transformer is a must if the unit doesn’t have a power transformer that provides isolation because these older gear often uses the chassis for one side of line but I use mine by default. Enjoy but be safe! I as a minimum have a GFCI outlet as well.

[@UsagiElectric]

A Variac and isolation transformer is definitely on my "must get" list. Fortunately, every piece of HP gear here has it's own power transformer, so isolation shouldn't be an issue (as long as the power cord isn't frayed or broken). Also, when I'm powering up any of these old pieces, I keep everything on a surge protector and keep my toe on the master switch. If anything seems amiss, I hit the switch with my toe, cutting power to everything quickly! It's not the absolutely safest way to go about it, but it works well with what I've got.

[@mr.salisbury2435]

@@UsagiElectric understood but honestly a dim bulb tester would take you about 15 mins to make. I just got one of those 5 dollar lamp holders from Home Depot etc , a piece of scrap wood and an old appliance cord. You see guys with the more fancy set ups for convenience but you don’t need it

[@aleksandrgusarov]

My best No.1 HW debug rule says: Always start from power supply first)

[@UsagiElectric]

That's a fantastic rule, and one of those things I tell myself to do and then never actually do, haha. It would have saved me some headache in early HP troubleshooting though!

[@shinedom]

The freq, counter has been already talked about from mr carlson's lab... its very interesting... i vote for its' restoration

[@UsagiElectric]

The frequency counter is super cool. There's a lot of really interesting mixtures of digital and analog design going on inside of it that I would love to do a deeper dive on! Thanks!

[@ooze9808]

I recently bought that exact same HP vhf signal generator at a yard sale. When I plug it in the tubes on the inside glow but im scared to turn it on. What does it do and whats it meant to be used for? Is it valuable?

[@_f355]

it generates the VHF (very high frequency, 30-300MHz) signals, and it is used to test and align the equipment that uses those frequencies, primarily FM radios I guess. also, if the tubes glow, it is already on - the on/off switch is before the main power supply transformer which generates the heater voltage among other things.

[@UsagiElectric]

Konstantin beat me to the punch, but he's totally on point! It generates a very high frequency signal. The 608D in particular can generate a signal from 10MHz to 420MHz ranging from 0.1uV to 0.5V in amplitude. It's a decently popular piece of equipment among HAM radio operators as that's the range that their communication radios tend to operate in. And as Konstantin pointed out, if the tubes on the inside were glowing, then the machine was already on and powered up! If it didn't let out any magic smoke, that's good news. If you have a modern oscilloscope that can read above 10MHz, you could probably hook it up and see if it's outputting a proper signal. As for whether it's a valuable piece of equipment or not, it's hard to tell. I got this one for a very reasonable price from a fellow enthusiast, but depending on where you live the value can vary pretty wildly.

[@kasel1979krettnach]

there is a good video on youtube on how to vaccuum impregnate old flyback transformer. you want the link ?

[@UsagiElectric]

Unfortunately, I don't really do much with transformers, particularly flyback transformers, so I'm afraid it would be lost on me!

[@ropersonline]

18:10: "There are some stickers that I would like to remove."

[@mr.salisbury2435]

Make sure to discharge HV caps before handling them !

[@UsagiElectric]

I cut the videos up to try to keep the pace of the overall video nice, but rest assured, I took all the necessary precautions off camera!

[@vladnickul]

it looks like you have some dead tubes in the 608D

[@UsagiElectric]

Good eye! I actually though that too, but those tubes have the getter on the side, so the top of the tube is clear. It looks really weird to me and always throws me for a loop, but they should be good!

[@DanielSmith-tn8un]

The good old days , when a electronics technician actually traced out the faulty components ,

[@pragmatologist]

Although my wife has gotten used to my various boatanchor finds, she would literally strangle me if I hauled all of that into the basement shop all at once...☠

[@KA2ZEV]

Boss, I think you should work on the meters first. Think you will find them superior to what your currently using. Mike in Virginia Beach

[@mr.salisbury2435]

Suggest looking at Mr Carlson channel as he has done a lot of this stuff. One thing he has said a few times is the red Spragues are film and very robust. You need to be careful handling HV caps -they can hold a nasty charge

[@UsagiElectric]

Thanks! And I agree, those VTVMs would be excellent pieces to have on the bench!

[@frankowalker4662]

The HP 711A PSU is the most useful, For the front bezel you could try Hand Mouldable Thermoplastic. Here is a link on how to use it kzbin.info/www/bejne/pJmYaKCpgM5seLs. The HP608D VHF Sig Gen is a gorgeous bit of kit.

[@UsagiElectric]

I agree, I think the 711A would probably be the most immediately useful, but if any of them were fully restored and on the bench, I'd totally find excuses to use them all, haha. For the bezel, the current plan is to build a wire framework on the inside and then build up body filler from there. There's going to be a lot of sanding in my future, but I think I can get it looking pretty good!

[@frankowalker4662]

@@UsagiElectric I would be nice to see them all lined up and plugged into each other. :) Nice and toasty, too. LOL.

[@VandalIO]

You might overwhelm yourself with so many projects

[@UsagiElectric]

Well, I didn't exactly state a timeline. My hope is to get at least four of these fully restored and working in 2022, so I'm definitely taking things slow to make sure I don't burn myself out!

[@VandalIO]

@@UsagiElectric that’s awesome :) hope you are getting better, and would love to see more interesting content from you

[@arthurjean-luc8040]

ohaaa quelle chance de trouver ces appareils

[@UsagiElectric]

Thank you! I was very lucky indeed!

[@bronka42]

power supply first! power supply first!.....in ....japanese!

[@UsagiElectric]

I don't know about doing it in Japanese, but I do want to do another episode in Japanese soon! I think that one will be on the triode though :)

[@bronka42]

@@UsagiElectric we don't know Japanese either! I don't even speak English! (ok, just a little) I owe everything to saint google translator