The BEST VTVM? You Decide! HP 410B Restoration and Alignment
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- Опубликовано: 19 июн 2024
- The Best VTVM out there? Let's find out. See a comparison to a modern DMM. Here is the restoration and alignment of an HP-410B Vacuum Tube Volt Meter. Click the SHOW MORE tab below for links.
To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: / mrcarlsonslab
#learnelectronics #restorations #electronicrepair 
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To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab
Thanks for the fine work you do.
Maybe you can find a HP oscilloscope to restore ?
Just a little history: Hewlett-Packard introduced the HP-410B VTVM in 1950. It replaced the HP-410A, which HP introduced 4 years before, in 1946.
Hi Trev0r98, I have a H/P- 400C not the same but a fine instrument.
@@garybevis8691 Nice!
It's always a pleasure to wake up and see mr carlson has uploaded a new video. You are awesome 💪🏾
Good morning!
Oh hey, I repaired one of these a few years back. Thanks for tripling the resale value :)
Snekers , Paul did tell the Patreon members and supporters of the impending rehab info to properly allow them to obtain any currently on Ebay, etc.
You don't know just how right you are about the value increase due to Mr Carlsons videos and him telling everyone you must have this 410B or other equipment he prefers . Says alot about his qualifications and expertise which are extremely high .
However, yes anything he talks up turns into a 280.00 ebay purchase as well as his liking The Heathkit IT signal tracers that are today 225.00 to 300,00 .
Yay! HP goodness, restored to perfection! You got a particularly nice unit. It’s hard to find them complete with probes, let alone one as pristine as this one.
Thanks for stopping by Marc. I always enjoy your video's as well!
@@MrCarlsonsLab it would be nice if we could see some restorations that didn't start with perfect gear. That only happens in the lab, not at any ham swap meet or estate sale that I've ever been to
@@weekendwarriorweldingdiypr4604 Here you go: ruclips.net/video/DzaiZtRoqs8/видео.html
@@MrCarlsonsLab I love all of your restorations, you do a great job! That's why I very been a supporter on patreon for almost a year.
OMG, when I saw that Mr. Carlson was restoring a piece of HP test equipment I thought of Curious Marc, and here he is!
It's amazing how you find old equipment still in good condition.
I think old equipment finds him. I'm sure he has many connections with people who know his abilities and ensure equipment deserving his touch make it into his hands. You and I are stuck with the crap people sell on Craigslist or swap meets.
Now I did find a nice Kenwood receiver on a Web site not too long ago. It's a Kenwood KR7070 more of a high end unit with auto tune and such. It's circa 1969 all original. It sounds awsome!
Silver band - 10% tolerance - 7.47K is just within spec for 6.8K nominal, so that resistor could easily have been 7.4K when i was installed. As you've mentioned in several other videos, Allen-Bradley resistors rarely drift.
Yep. Appears white on the video, but it is definately a silver tolerance band on this type resistor.
Yep, if that tolerance was ok for the lab that built it, why replace it if it looks and tests ok?
I think while modern resistors are mostly produced to spec, those carbon composition types had a lot more variation in production and I wouldn't be surprised if they were checked how they turned out and then labeled accordingly. So instead of the roughly bell-curve distribution you expect to get today it would have been much more evenly distributed.
Now it is time to restore my HP 501C, thanks much for this video ( however I must wait the new bench is under construction), Blessings, Albert, KR3HAB (new call)
Wow Professor Carlson thanks for a blast from the past for me. I graduated from a vocational tech high school in 1972 and my trade course was electronics. We had a few of those vtvm's during lab work. So long as they were cared for, which we had to do as well as part of our learning, they worked good I must say. Thanks for the memories.
Glad you enjoyed it Don!
That is a fine VTVM. I used those when I was in the Air Force and worked avionics. I would really like to find one : )
I use one frequently still, and I have three of them at work
I'm impressed with the way the needle acts like a perfect control system, no over damped not under damped. It just jumps to the reading and stops there. Very quick and precise.
Interesting old meter. Its successor the 410C is even more interesting. Probably the epitome of analog meters it had the optical chopper like your other meter. It had a custom marked meter scale to match the movement exactly. Can you imagine photo graphically exposing film to make a special scale for each and every meter movement? With chopper circuitry it would read mV levels so you could read thermocouples directly. It has the same AC probe with a tube in it. The meter circuitry included one tube and some transistors. It was very simple and even fits on one page. While the 410C was pricey in its day a DVM at that time would have been much more expensive probably 5-10X. When DVMs dropped below $500 in the 70's I'll bet not too many of these were sold. I used one regularly along with Simpson 260's and other VOMs before we got DMMs. After that I rarely touched it. I was always impressed by its simple and elegant chopper stabilized design. I still have one just for fun. But then Phillips had chopper front ends on their scopes back then and never drifted unlike Tek's on which you chased the beam around for the first hour or so. Not well known but Phillips scopes were vastly better than Tek scopes in many ways. You ought to do a 410B 410C comparison video. I could lend you a 410C if you don't have one.
All HP dials on signal generators were engraved after each unit was calibrated. the engraving machine was driven by a frequency counter so no two knobs or scales were identical. I was surprised by my first tour of the RF production line tour in the early 60s. They wanted young future engineers to get attached to HP so conducted events for groups of 5-20 nerdy 12-18-year-olds and assigned an engineer to each of us as a mentor for personal guided tours. Bell Labs did the same thing back east. It was a different era, none of the kids ever asked about salaries or stock options as now, we all would have worked for free. Any job in the late 50s and 60s was a living wage job that could support a family so no one even thought about money. I was particularly interested in RF and MicroWave so got a full tour of all the production process and still have vivid memories of that tour. I was given the phone number of my engineer mentor and when I was building all my self-designed gear to attempt moon-bounce two-way communication on 432mhz I asked questions several times.I was just a 16-year-old kid with two clock-driven parabolic dish antennas and all homemade equipment and made local headlines by being amount the first to succeed in two-way com via moon bounce. The army did one way with an unlimited budget in 1959 but this attempt was two way between me and Cornell University radio astronomy grad students who had access to the 1000 ft dish radio telescope at Arecibo PR. I never worked for HP but those experiences and my fondness for the test equipment division never faded. I ended up with a large recording studio that became very successful in the 70s to 90s. I was never interested in music and never learned to place an instrument but had a knack for creating sounds that become hits. The studio had 197 gold, platinum and Diamond albums. mostly consecutive in 3 studios. Of course, the studio maintenance department was full of HP test gear from my large private collection
Outstanding, Please don’t stop, I’m hooked.
I have one of these in my meter storage that I haven't done anything to. I'll have to pull it out and go over it now. I thought it was missing the probes, but maybe they are tucked in the back. Going to have to check now. 👍
You did a masterful job of this video. I am very impressed with this VTVM. Something that is special about the 410 is the DC input resistance, more than 100 megaohm. The more common VTVM's on the used market are 11 megaohm DC input resistance, so they will load a circuit in a similar manner to a DVM (10 megaohms usually)
True, the 4x0 series including the 410C and all the 400 models of AC meters were perfect for circuit analysis due to that high z input that was needed in sensitive tube and FET circuits. The 410a, b and my favorite C were flat to 700Mhz and any design or prototyping work in RF, that was the meter series to use.
A classic piece of test equipment Mr. C. When I left Teleradio Systems in North Van just before it closed down I managed to purchase my 410B and that was over 30 years ago. Still used regularly on my home work bench but thanks for the reminder to change that electrolytic before it causes problems.
You're very welcome Rob.
aaaahhhh memories....in the '60s my first VTVM was an EICO. The 12AU7 in mine would go soft after 20 hours of use. The most frustrating thing using it was, every time the range was changed you had to re-calibrate. More accurate than a VTM in those days. My first tube tester was a Heathkit. Worked great.
Thanks for sharing
I was overlooking this device until I heard your comment on the circuit loading performance. Learning something every single time I watch your videos.
Me too, I know so much less than I think I do LOL
These videos bring back so many great memories, for decades I collected test gear, mostly HP, GR and Tek and had restored units of most of what HP ever made. Living in Northern California a few hours away from HP the equipment swap meets held early Sunday mornings with hundreds of collectors, many where engineers at HP who were involved in designing the gear so any question got authentic answers. The old stuff was cheap and I had an old VW van that was only used for hauling get back from those meets. Any part or assembly needed could be found if one knew what they were looking for. My main business was a large recording studio in Sausalito but I also had a large 23 tech repair shop for pro audio gear and a shop in the mountains which had contracts for two-way radio repair for agencies of city and county but mostly for 3 National Forests so that meant collecting RF test gear also which was handly for my ham radio hobby projects also. The studio had 4 full-time techs plus me when I was not engineering, but as the studio became a top studio the 3 studios were booked constantly with major projects which had their own producers so I spent more time in the lab designing new gear and playing with repairing and calibrating test gear. In the big repair shop with 23 techs, each had 2 fully equipped workbenches so waiting for customer est approvals meant the tech could move to the next bench and take in a new project without reassembling the first one. When applying for warranty status for major brands, they always wanted a list by model and brand of test equipment and the standard list I sent had 524 pieces of HP, Tektronix, and Sound Technology test gear, taking up 32 pages. A few times they sent reps to see if we were lying. All that restored and calibrated gear was from those swap meets. In my second barn in my ranch, up in the mountains 200 miles away was a large storehouse of parts, units to be restored, parts units etc for test gear, ham radio, RF service monitors etc. 20 years ago I gave it all away to employes, girlfriends and moved to another country and for the first few years I returned twice a year and brought back what I could bring in suitcases and in 5-6 years I had enough for a pretty complete RF and Audio workbench in my city center 250-year-old apartment in St Petersburg Russia and still do repair, mostly for fun of audio gear like guitar amps and mixing consoles. About the only thing I miss is that collection of test equipment but I have too much fun here with too many young girlfriends and cultural performances nightly or dancing in clubs until 5 am.
Your videos are a delight for a committed nerd. By the way, speaking of 410B, I naturally had a lot of those but also 76 400FL or GL AC meters, and my personal favorite bench VTVM was the 410C. It was a lot more modern looking and was smaller. I had 38 HP333 or 334 distortion analyzers and a dozen of my favorite HP3580a audio spectrum analyzers. I have one here that never needed work and used daily but the HV when out and it appears the high voltage transformer has failed and for 2 years have searched for one with no success. Maybe you have a source or know of a junker that I could steal one from.
Happiness is a bench full of HP and Tek test gear....
Love a new Mr Carlson vid!
Paul, I really like how you include the alignment procedure in your restoration videos, I just followed along and aligned my HP 410b with you.
Thanks!
Thank you with respect, you Master of Tubes!
Mr Carlsons statement re DMMs should be only considered correct when comparing with VTVMs like the HP which have mind blowing specs. A regular VTVM might be very similar to a regular DMM which is fairly standard at around 10Mohm.
Hey Paul. I'm always in awe of your knowledge and capacity to repair the old equipment that you do. If only I had the brains to learn more about electronics than I know now.
Such an incredible amount of detail, thanks for all of the hard work!!
What a great restoration, who knew VT volt meters could still be so useful !
I spent a long time working in the Navy Metrology/Calibration program, and then in the metrology department of a major US airline. Both organizations tend to use test and measuring equipment to its bitter end, so I have worked on a few 410B and a LOT of 410C units in my time. An early experience with one of them was when a sailor brought one in from a ship, to be repaired. The complaint on the ticket was "Made a noise, then started smelling green." I chuckled a bit, because that made initial troubleshooting really easy -- check the Selenium rectifier first! As expected, it was no good, so it was replaced with a silicon rectifier. (Selenium rectifiers were obsolete by then anyway.) Then go through the minimum performance test to uncover any other issues, then do the calibration procedure and the paperwork, and notify the ship to come and get it.
The biggest problem I recall us having was that certain users did not like the DC probe for some reason, so they would CUT IT OFF and replace it with a pin terminal. The problem with that was (IIRC - it was over 30 years ago) a 10 MΩ resistor in that probe! So by doing that they were instantly making uncalibrated DC V measurements! I don't recall what, if anything, management did about that. But what really concerned me was that the department involved worked on some strategic weapons systems!
But I would still love to have one on my bench now.
Thanks for sharing your story Graeme!
Just beautiful! I can smell the real, honest flux.
I love how close so many points were close right out of the chute too, but now it has been taken to infinity...and beyond? ;)
A fantastic video journey into a vintage VTVM. Thanks for showing it and your really big probe!😉
Hooray mr carlson is still alive and a new video to watch many times
Hi Paul. I have a 410B but have not done anything with it. Your video will be very useful, thank you.
Glad to help!
Always some neat stuff to do in Mr. Carlson's Lab.
Great video. I had the transistorized version of this from the late '60s. It was a great meter and I'm sorry I gave it up.
Great video. Gives me inspiration to restore my 410B! Thank you
New Slab Day! Always enjoy a new video from Mr Carlson Slab.
Like so many others have commented, we used these back in the polytechnic high school electronics lab I attended most days of the week back in the '70s. Fabulous.
I always kinda wonder, who’s giving down votes on your videos? I ❤️them!
That was great Paul. I just love to watch you work on old tube type radios and equipment. Probably because I use to hobby around with them many years ago.
Glad you enjoyed it Gene!
Thank you for posting. Excellent!
That for me... Was a very, very educational video... Lots of information was conveyed about these old tube voltmeters, and the example of loading the circuit using modern digital meters... VS tube voltmeters absolutely demonstrates the difference on measuring sensitive circuits, And using a "Magic Eye" to show us... Was an excellent visual example, using these 2 types of measuring devices, and what needs to be understood using these 2 different measuring devices was an excellent demonstration. All these years I thought it was the Opposite... Tube type testers,... Would load the circuit, Not only did you explain what's going on, but you visually demonstrated this important lesson, :-) I now want to look for one of these types of voltmeters, there could be a lot to learn, Using one of these meters, you have given me a lot of things to think about, with his video and in time, my experience, doing repairs will be done with more knowledge and understanding. Thanks for the great video. Now, off to Mr. Carlson's Patreon lab... :-)
Awesome video as always! Thanks Paul! Cheers!
That thing is absolutely adorable looking. HP made some really awesome stuff. Thanks for the handle tip!! Some old leather is absolutely worthless.
Yaaaay, it's couch time with Mr. Carlson again 😀😊📺
too cool I used to calibrate those when I was in the Navy :)
Mr. Carlson, I own two different military versions of the HP 410 B and very happy to have the military manual plus updates to boot. The difference between the two is the serial number ranges. HP replaced several values of components dependent on the updates. Also, the selenium diode is backwards in the original schematic. HP 210 Bs are great reference meters.
Very cool =D Super accurate there too!
Very interesting, Thanks for sharing Paul.
I just repaired my 410B!
Mine was used for decades in an avionics lab, but it was considered obsolete and given to me.
A few pots to clean, a wire soldered, and it aligned nicely.
What makes it even more valuable, are the two AC probe adapters I got with it, they allow me to measure inline coax voltages, or the output of a signal generator!
It sits on my scope stack, ready to measure whatever needs to be repaired!
Sounds like you have a great tool now! The 410B is really fantastic.
Lucky bastard! :)
@@Pootycat8359 Sometimes we get lucky, and sometimes we come when the dumpster was emptied yesterday, when everyone else picked out what they wanted!!
I really like the old HP meters. I have the 410A. Been looking for a B version for some time now. Thanks for sharing Paul.
I used HP test sets at AT&T. Years ago we had good quality tools and test sets.
Thank you I have a GM custom 2400 your info is priceless to me Thanks you so much
Love the videos, will patreon as soon as I can afford to, need that cap tester. Fantastic channel
HP always did make top-notch equipment.
And I just recently scored one of these off an auction site, complete with input probe. :-)
That's the FASTEST D'Arsonval movement I've ever seen!
Wow, I've had one of these sitting on the shelf for decades and in similar condition, so I had to pull it down and follow along the resto with a lot of extended pauses.
The only things missing from mine are all three probe tips, even the AC one, there is a plastic screw on end cap with the needle in it.. I can make that part (maybe with a swappable shorter needle), the other two probes look like they use collet retained probe pins with a threaded locking collar, again I'll make these, and lastly the blue front badge insert is gone, but I could probably print something and mount it behind a piece of clear plastic. I was using an AVO8 for analogue duty literally forever.. until now..
Thanks Mr Carlson.
I have a 410BR, the rack mount version and it's awesome!
Hi Paul, great video, I expect no less from you. About a year ago, you make a video concerning the Sentinel ME-26D/U, you tipped me off to the HP 410B. I have the H/P 400C, VTVM only purpose for A/C measurements. Quite fine instrument, which I fully restored back to pristine condition. So I set out to find a the famed H/P 410C. I found one on eBay, in like new condition, fully restored by a nice gentleman from the Silicon Valley. Unfortunately he was asking $350.00 a fair price it would seem. But alas I did not have the funds for such a instrument. I have looked high and low, no HAM swap meets for more than a year and nothing on eBay. I will look at HAM meets that hopefully start up this Summer. Take care Paul and again thank you for all you do.
I used to walk work on Marconi TF10 41b vacuum tube voltmeters, they really are a fabulous instrument.
..Да.. Они не боялись ошибочных подключений..
@@user-rt4rh2sm9i Sory, only English.
Hewlett-Packard (HP) equipment in the modern US Navy has a DoD Code Name CAQI. It was (and perhaps still is) the most widely-used manufacturer of electronic test equipment in US Navy ships from at least the 1960s, if not earlier. The simplicity of the construction of its portable equipment is because that is part of the military specs it had to meet and so it just made EVERYTHING like that to make sure it kept its position as Numero Uno in such VERY sought-after and highly-profitable contracts.
Informative and à joy to watch as usual!
Glad you enjoyed it Wojtek!
Marvelous item !!! ( HP ) thanks for this vidéo Mister !!!
It's very impressive for me and please be caful in this trouble time .God bless you and your familly
Eric from France ( and sorry for my English ...)
Nice demonstration on a very cute VTVM!
Have seen in the manual, that the input impedance at DC is app. 120MOhm!!! That´s why it´s better than many modern digital multimeters - want also one!
Educational and fun to watch. Amazing an instrument that old is still spot on. I've had many DMMs that were far less accurate. HP made some amazing quality test equipment. (though I'm not as impressed with their recent laptops) Curious Marc would approve. lol
I’m amazed how fast that pointer moves.
Good morning Prof Carlson
Good morning!
Thanks for another great restoration. I am lucky to have one on my bench, along with my fluke scope meter. 👍
I used to work on these. Great meters. High Z. Good accuracy. When American companies quit making Tubes we had to source them. I used to laugh. The new ones had a hammer and sickle on them.
HP made some great test equipment. Didn't care for their Oscopes, but the SpecAns snd Signal Generators were great.
Thank you Sir I have been waiting for a new video........You have the best site on the internet...
Thanks for your kind comment BP!
very interesting mr carlson thank you
You are very welcome James!
A tube inside the AC probe? Nice. I think my wife would love it because of her always cold hands. 😂🤣
Nice thanks for the video.
I use to own a HP-410. Great meter. Got rid of it back in the 80's. Wish I would have kept it.
GTCGreg , I wonder what the difference was with a model 410 which went for just under $300 on eBay the other day.
@@BruceNitroxpro I have no idea. I got rid of the one I had almost 40 years ago. I gave it to a neighbor kid that was interested in electronics. It was complete and working well when I gave it to him. I gave him quite a bit of other electronic test gear. He eventually went on to get an electrical engineering degree. I hope the test equipment I gave him helped inspire him to do that.
@@GTCGreg , Superb! But, if he was silly enough to get rid of that meter, he will almost certainly crap a brick! LOL
Absolutely beautiful 🤗 I also love the pink panel neon indicator lamp: very 50s sci-fi _Forbidden Planet_ 😍
They are actually red but in the video it did appear pink.
Thank you for another great restoration, Mr. C! My wife thinks my viewing of such videos is odd, but I really do enjoy seeing you dig into vintage meters and scopes, and I learn so much. I've watched you restore three different VTVMs: this HP, the ME-26D/U (the Mil version of this one), and the Knight KG-625. You suggest that this might be the best VTVM. If you prefer this HP over the other two, however, I'm curious why, and I suspect others are equally curious.
Need more radio repair shops in the UK 🇬🇧
Years ago, I won a Best in Show at a competition of Houston Vintage Radio Association, exhibiting one of these instruments along with the little Eimac diode tube that went in the RF probe. The zinger in my entry was a set of cuff links and tie bar featuring the same tube - some kind of swag for HP customers.
Well, I finally managed to come across one of these on an auction site and snagged it. The DC and ohmic leads need to be replaced, as the insulation is pretty badly cracked on them, but other than that it looks pretty good. I'll be using this video as a guide for my own restoration.
Nice restore Paul, done with your usual care and attention. Interesting seeing the loading from the DMMs as compared to the VTVM.
Thanks for the kind comment David!
First, I want to make clear that I enjoyed the video, and I love that this kind of information is available, and I am a patron of the channel.
A comment about input impedance... Modern hand-held DMMs tend to have an input impedance of 1 to 10 Mohm, according to the paltry amount of relevant information I was able to glean from checking the data sheets for several DMMS, including the Fluke you're using there, my Flukes, and my Flir DMMS.
I have several DMMS that have a LoZ (low impedance) mode. These are useful to avoid ghost voltages, which I deal with a lot because I do industrial electrical far, far more often than I do electronics. I have seen the 'loading' that you refer to, and it *is* annoying. A VTVM is not convenient to carry in the field, though. If I decided I wanted a DMM more than I wanted a new car, I could buy a Keithley 2001, which is rated for over 100 GIGAohms of input resistance when measuring DC voltages up to 20V. I can't imagine that this VTVM has that high an input resistance... could it? Certainly it would be cheaper.
I'm not sure what my point is. I think it's that analogue meters have benefits that digital meters don't, but that doesn't require the tubes. I don't think that the tubes add a unique value - you're comparing that bench-mount machine to pocket-sized DMMS (okay, that VTVM has a handle, but it plugs into the wall and it's hardly in the same portability class as the units it was being compared to). Compare that VTVM to a modern bench-mount DMM like the Tektronix DMM4050. It costs about what that VTVM cost new (adjusted for inflation) and it has a rated input impedance of over 10 GIGAohms in the voltages you were testing. I believe that it would hold up very nicely against the VTVM. If you want to spend a whole lot less the Rigol DM3058E has basically the same impedance specs as the Tektronix for around $500.
Anyway, I guess my point is that this comparison was really showing the shortfalls of hand-held DMMS, not so much the benefit of VTVMs.
Ah, but try using a DMM near the base of the tower, fed by a 50 KW transmitter! (been there, done that...) I think that's why Simpson & Triplett still make their good old 260s, 630s, 310s, etc, and sell them for big bucks. I"d guess that broadcast engineers buy most of them.
Excellent video as usual but I would have liked to see you do a schematic breakdown of the operation, I'm just spoiled by your other videos. Anyway, now I have two of these to rebuild and align myself!
A couple of small notes. First, there are differences in digital meters regarding their inout resistance. I remember noticing that at higher voltage selection some high sensitivity analog meters could have lower loading than early digital meters. Then the digital meters started being "standardized" to 10 Meg input resistance on all settings beyond 2 V or 20 V. A Fluke 8060 had special "trick" to bypass its 10 Meg resistance, by leaving one or two selection buttons not pressed and producing 10 G-ohm.
Second, I hope your AC probe pn was made of brass screw, rather than steel. Otherwise I would be skeptical about its abiities to get even beyond some MHz.
Third, I was once puzzled by missing heater on the input stage of a Keithley meter. Actually I learned that it was intentional - the meter was Electrometer. It depended on the cold cathode tube for its input characteristics.
Fourth, if the selenium rectifier would be damaged, you could smell it way before ever opening the case. "Ask, how I know!"
Many of those nasty DMMs have high impedance modes. The venerable HP 33401A on my bench is 10 megs normally, but in the auto mode, on the 100 mV to 10 V ranges input impedance is > 10G ohms. My handheld Fluke 87V also has a high input impedance mode, but only on the 600mv DC range. Thanks for the great video! I love the old HP and Tek gear that have (mostly) replaceable parts, and comprehensive service manuals.
Enjoyable video. The probe on the military version looks like a 'willy'!
It's what aliens use if they get you in their spaceships!! Lol.
Cool video, i just found your channel
I have old hp digital multimeter for bench not transportable and use it daily it is great.
I also love restoring old devices ,mostly i do professional audio.
Glad i found your channel im little short on time to watch your videos because i am at college for electrical engineering, aswell at electronic tehnician full time job but still good one to have I will gonna try to look over what i can very informational videos.
Greetings from Sarajevo
Omer
Welcome aboard!
Best? I will submit two for consideration. The HP-412A which sports a full six ranges below 1 Volt DC. A magnificent device with the chopper light circuitry, and parallax mirror. And number two, my favorite actually, the Simpson 314, which is actually a solid state unit, with the biggest cleanest meter face of all. Superbly accurate, and a true pleasure to use. Useful at low frequencies as an oscilloscope, with its needle cruising back and forth like a metronome, about the center zero. Both will measure higher resistances than my reference Fluke 8842A.
You may find this interesting as well: ruclips.net/video/vrmwql2msbU/видео.html
I always wished HP had added a parallax mirror to the dial. That's a brilliant feature of the Simpson 260. One gets used to checking parallax every reading, and that causes a moment of confusion on dials w/ no mirror.
Gible535 , You have to wonder! This design obviously earned an upgrade!
@@LordPrecision , Keysight sells meters with ONLY .05% AC ratings... if seven or eight digits will do.
@@BruceNitroxpro FYI, Keysight is the current name of what used to be HP's instrumentation division.
@@drtidrow , Aha... an interesting fact. The people I hope are still there which gave us such superlative intstrumentation.
@@BruceNitroxpro They were also part of Agilent back in the early 2000s.
Looking at their website, they seem pretty proud of their HP legacy, so I'm fairly sure they're living up to that reputation.
Happily I own 2 of them. One original and one someone put in a homebrew case many years ago. The tube in the probes were made specifically for this meter. They are expensive and hard to replace! Often they sell for more than a complete meter, if you can find one. That is until now, because of the "Carlson Effect" that will drive up the eBay prices for the meters for the next couple years!
Give me an analogue meter over digital any day. Never heard of vac tube meters. Still prefer an AVO 6 or 8 for more sensitive or time consuming problems, a cheap knock off fluke for the day to day stuff.
For me it's the resolution that I stick with analogue, digital one's hunt more to my mind.
Gorgeous meter. And every time I see that tester of yours I grin at just how amazing it is
And damn, that first sweep of the needle as it warmed up gave me goose bumps and holy...... how sensitive......wow. This is why I love old school analogue stuff.
I truly enjoy your videos and may add a quick question to this. I have the other meter you talked about and what to tune it up. Thanks for your hard work for us.
Extremely nice meter! Really a beauty.
Great video!
I only don't really follow the super accurate story of it.
For example, when reading the 200V, it has a line for every ten volt.
Everything in between one has to guess. So say your total accuracy is about 3 volt with good eyes and tongue at the right angle. Although there is no mirror for parallax compensation, so often that is more like 5V.
So the total reading would be at best 200±3 V or 200.0±5 V, not so impressive for nowadays standards.
For example, try to read accurately 164V
Most decent DMM's these days do an order of magnitude better and therefor fall well within spec of these meter.
Off course one can also just calibrate these meters to have the exact reading, although in general they still fall within spec after many years.
Some HP 410B's came with a foot long high voltage probe that allows you to measure up to 100,000 volts. One thing I've never cared for about these meters is the smaller meter face. One nice feature is that the resistance measuring circuit uses line supplied current as opposed to a battery which tends to be forgotten and ends up corroding the insides of many VTVM's.
Great video, Paul, as always! You mentioned that you'll be designing a tube matching circuit in an upcoming video. Will it also have a way to measure transconductance? It'd be great to have that as my B&K 607 tube tester lacks that ability and the gm capable testers are beyond my price range.
Thank you Paul!
My pleasure!
@@MrCarlsonsLab Paul, I have been going back and forth trying to decide whether I should ask this or not but I'll ask anyway. You are, of course, the person to go to when you want to know probably anything about radios. I think what set you apart from others in this field is that you know the theory well, you have a lot of practical experience and most importantly, you have all the physical and mental tools to explain it in such a way that almost anybody can understand it. In your All American 5 Video, there is a short part where you explain the signal path in the radio. Would it be possible for you to do the same in a separate video, on a simplified version of a tube radio built on a simple chassis, going through the signal path using some sort of test equipment (an oscilloscope for example or whatever you see fit) and explain how reception occurs starting from the antenna all the way up to the speaker? I do understand that there are different topologies for radios, like regen, heterodyne, super heterodyne, etc. but since I don't know much about the classification, I would ask you to do whichever one you see fit (where would one begin?). If you have done anything like this on Patreon, I am working my way through to Patreon and I'll get there soon. I am going through your RUclips videos currently. If you don't find the time to do this, I would also be interested in any book or resource you would recommend. I thank you in advance. -Regards Gahra
Nice one Paul! 👍
Thanks 👍
Very nice! Especially liked the part about calibrating the infinity position so the meter tracks dead on as the range switch is moved. I wish my Knight KG-625 had that ability. I'm always adjusting it between ranges, as well as the zero position when switching between positive and negative measurements. Is there a way to correct this behavior in the Knight VTVMs?
I was able to pick.up an HP 410B on eBay. "Property of the USA" with calibration dates of 98164 and 98169. On the front is Warner Robin's ALC 14 Sep 1977. My AC calibration board is labeled and all the pots are on top of the board with 30, 100. and 300 top to bottom. I have the larger 2-01C tube in the AC probe. Needs some cleaning, and I am looking forward to seeing the updates!
The Hickok/RD Instruments 1600B is a very similar instrument made for the Army. It's different enough that it wouldn't pass for an HP instrument, even on the inside, but the circuitry is still very similar.
I think it would be cool if someone took a VTVM (maybe not a pristine one) and added the front end of a DMM as well. Then you'd have the very high impedance back end with the easy to read display, while still having the analog meter movement. Hmm... wish I wasn't too lazy for a project like that..
Nice meter!
Awesome