This brings back memories. I used one of these in 1978 on a daily basis while in the Army working on a MSC-46 satcom earth station. It was also typically part of the test equipment pool available for the next few years in the commercial realm after I transitioned out of the service.
Hi, absolutely amazing video, I bought a HP427 a few days ago and was looking for information on the restoration, or rather the problem areas (not counting the capacitors). I have come across a few videos on restoring the HP 3400 and I am not afraid to say that this is the absolute best I have found for this meter. So not about the meter as such, but about diagnostics and measurement, thank you very much for the information I got from you, maybe I will buy one in time (when I have the money), it is not so simple in the Czech Republic. Channel subscription started 😁 Nice day 🙂 Tom
Excellent content, thank you for making this. I was looking at HP voltmeter documents from the 1960s, looking at all the models, deciding which one should I get. Your video made things clear, you explained the advantage of the 3400A very nicely. I will definitely get one if I ever come across it.
Sir, you are a wonderful teacher. I am learning electronics again. It was my job in the Navy many years ago. I followed the video closely ~ took some notes ~ did a little math. Thank you.
Interesting video, still have 2 of these that I use. Good tips on improving and maintaining them! Also have 2 HP4303c, the later 100 MHz digital display variety of these that I bought way back. I recommend Jim Williams excellent writings in the old LT application books, that is why I bought these then rather expensive meters. Those books are still a valuable read if serious about analog design.
The boss, at a shop I worked at long ago, loved HP equipment. I remember seeing HP AC volt meters but can't remember the model number. The video brings back good memories. Merry Christmas to you and your family Peter. Also, have a Happy New Year.
HP are the kings of test equipment.....nuff said While at GEC in the UK in the early eighties, HP equipment were seen applenty and Tektronics as well......I was in good hands.. Very nice video, nice to see an old pal resurected... 👍 You have an impressive looking test gear setup there, must have cost a few bob (UK monetry slang)
Thank you Peter for your time and effort. Important information I learned from this great content. If you can show us the symptoms of reppled dc power supply on reception and transmission. Merry Christmas to you and your family
Thanks so much for this acknowledged Peter ! I have a Kikusui AVM13 and one Meguro MAK6571C, the alignment is very complicated and this video helped me so much to understand many concepts! 73’ PY2NDB
Nice restore for sure. I used to have a Heathkit 5225 FET multimeter that looked similar to that one. They're definitely accurate. Kinda wish I still had it haha. Happy holidays to you Peter and your family. 73 👋🏼
Have one here too. Its a super meter. I have just checked the caps in mine and they are all good. Not sure this one has had much use, Did do the opamp offset adjustment too. Happy New year Peter, thanks for the upload .
Hi Peter, very nice equipment, i love those old machines, i have some of them from my dad's bench when he worked. Have a good Christmas with your family and THX for sharing with us this video.
I was able to find a late serial number model of this meter on E*BAY and went ahead and purchased it. I'm excited about working on restoring it just like you did. I have a much older version of this meter from the 60's that was given to me many years ago, but I think it's too far gone to be able to restore it properly. These newer models have much better components and don't rely on the potentially bad neon bulb chopper like the old ones did.
Great video. I have a Racal Dana 9300B RMS voltmeter that is reading 8.5 mV RMS with the signal in your example. So not far off. This is a nice analog meter designed in the 80's with mostly discrete components. My unit is from beginning of the 90's. I have done some maintenance and upgraded a few components. The lowest range of this meter is 0.1 mV (lower than the HP) and it's bandwidth is good up to 50 MHz (-3 dB 57 MHz). This makes it ideal for measuring e.g. power supply noise.
I used an HP 3400A in the 1960's as a student. I now have three of them. Two work well but one has no movement of the meter and needs to be sorted out. I'l be interested to watch this video at the weekend.
I have this meter but it was made in the mid 70's and has the older "photo-chopper" circuit. While it still functions fine some of the adjustment points are at or nearly at their stops. The unit was serviced at some point in it's life and the power supply rails are still clean and stable and it's overall measurement accuracy is still within specification. The HP 3400A/B are the go-to meters for pulse measurements, but I mostly use it for power supply noise measurements.
@@TRXLab - Actually after I watched your video I replaced the power supply board in mine. I bought a NIB A7 board (REV B P-03400-66510) off eBay that was made in 5/89. I swapped it out and only had to do a minor re-calibration. However the things I immediately noticed during re-calibration is the resting offset is consistently low (2-3%), and the "jitter" is completely gone. All that is left to do is replace a few out of spec components in the attenuator section and it will be complete :)
Hehey this was yet another very interesting video you made Peter, i got one of thes instrument and i now will chek mine aswell. I have a few another branded allso, now is checking time!! Thanks Peter for this superb video, Marry Christmas and a very good new year to you and your's and every one who see this. btw Peter, i allso got a'n HP 432A Power meter and a few (3) Boonton model 92C , any video on some like this?
My particular meter has a Revision D A6 Chopper Amplifier board. The Op Amp U602 in your Revision C board has been replaced with a HP 1826-1381 which is cross referenced to Linear Technologies LT1012DN8. My board also has the trimmer you installed omitted. It is quite possible you could replace that Op Amp on your board with the LT1012 and get better performance without the need of the trimmer. The datasheet for LT1012 says it may be inserted directly into several different types of applications if the nulling circuit is removed.
This chaps amazing im so glad he dose the posts learning so much from them just wish could contact him direct I have a racal dviashion meater that won't go in to lock and from a ham radio ops point he realy dose some grate repair work keep up the hard work 73s de m0djf
Great video Peter. I was wondering where you sourced your filter cap with the nut chassis mount, I bought a hp 3400a and would like to keep it nice looking. 73.
I have the 'B' version of that meter and am curious where you were able to source the dual (47/47) capacitor? Thanks again for all your great videos and happy new year!
Hi, I found the right data sheet about this meeter, and old HP Journal Volume 15 numer 5, from January 1964 describe that this meeter are design for Low-duty-cycle pulse trains measurement it frequency range is from 10Hz - 10MHz. That should have the same results as the Philips one, but show more that the bandwidth should be higher. The same article describe that this instrument could be used as a AF, and RF power meeter, by connect to the Resistive load. Also is design to work as current measurement by connecting the Current probe 456A bandwidth up to 20 MHz. At the description about the input amplifier is mentioned that 3dB bandwidth is from 3Hz to 30MHz. That could be the difference between the spec of the power source, Philips AC meeter, and HP unit measurement.
correct but the difference between the Philips and the HP is that the HP is using thermocouplers to be able to deliver those results which the Philips don't have...
Yes that is a nice meter. The majority of this units have a nuvistor only the last batches are now equipped with Mos FET's. And the B Version is a complete different story... Guten Rutsch Stefan und ein gesundes Jahr 2022
Very nice video and Instrument, however the Datron Instruments 1061/1062 True RMS converters were tested at the factory to a 10.5:1 crest factor, which is better than this HP. I know this as I worked for Datron as a technician producing and repairing these instruments. The 1061 was the lowest in that range, with the 1071 and 1081 having even better specs. Of course, engineering is a series of compromises, so there may be some specs better than Datron- but HP thought well enough of Datron that they commissioned the company to make custom multifunction calibrators for HP- many of these are still in service since in their cal labs about 1982.
Those meters were in place at my first job which I started aged 16. They were still working well when I retired! shows that buying quality gear pays :-D
OK.. maybe I should mention. Crest factor is specified as 7 to 1 so it handles 7x peaks compared to average voltage..and good out to 10Mhz. The best ? The little known racal-dana 5002 is a 20Mhz (useful to 40mHz) widebsnd level meter with a crest factor of 4 to 1at full scale (300 microvolt to 100v) but rises to 12 to 1 at 1/3 of full range. That is exemplary..and these units can monitor down to 10 microvolts..but specified range is 30 microvolts to 316v RMS. Anyways..thought You might be curious as these are vintage now too.
It would be interesting to measure the power supply ripple when the power supply is loaded. Are the specifications for power supply ripple always stated for unloaded power supplies?
I have been looking for one of these to restore for a while but they don’t appear very often in the U.K. and the ones I have seen are in poor cosmetic condition.
Yes you are right good units are very seldom but worth to search for. Try to get a unit with a higher serial number without the old neon chopper circuit. Thanks for stopping by!
@@TRXLab very interesting.... So adding a short on the input should bring that closer to zero or it has little effect. Also, increasing the range (decreasing the sensitivity) should bring it closer to zero am I right?
yes for the first statement. Not necessarily as there is always a little noise and don't forget we are under 10uV and additional even the internal components are noisy...
Your HP meter is great gear, it was designed for RF and signal transmission work and is not a True RMS meter, unless I'm an idiot that didn't understand my class work. True RMS is a measure of the DC equivalent voltage over time, which compares to a signal ran into a resistor and the heat generated compares to the heat of an equivalent DC voltage. The pulse would have a very low RMS equivalent voltage because the "resistor" would cool down between pulses giving something like your example meter which I believe to be accurate. So, I believe both meters to be accurate, just that the HP is measuring the RMS voltage of the highest pulse, or digital block, or video block, but disregarding the "dead zone" which makes this meter perfect for measuring Max instantaneous power into a transmission line or antenna but the example meter would get the correct reading for wanting the voltage output inside a vertical circuit of a CRT for power consumed, just not the peak "Crest Voltage". Lots of really good stuff early on, especially changing out the old logic IC--brilliant.
Oh Thomas I believe you are mixing up some things. Yes it is a complex subject and I can't completely answer here in the comment section to all the points you raised. But I think that a HP technical information from the HP laboratories may help to understand the subject a bit better. So simply follow the link www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1964-01.pdf
@@TRXLab Thanks for the great HP Journal it is awesome. I think it makes my case perfectly, there is RMS, and there is RMS Crest factor which only looks at the highest peak of the signal. For periodic waveforms True RMS is great, for pulses and arbitrary waveforms that the highest signal level is of interest then you need the RMS Crest Factor measurement. Thanks a lot,
@@marko6550 I think I understand the article and I remember my electronics class where we dove into RMS AC. I think where we differ is something called instantaneous voltage and RMS voltage, and if I was taught correctly, what ever you measure instantaneously is peek voltage at that time. I think that a pulse peak voltage doesn't represent true RMS at all because you are not accounting for the loss of energy at all the other slices of time that DC equivalent would get credit for. Having said that, you may be correct as far as EE's are saying these days since many of them may only be interested in the crest portion of the measurement.
@@marko6550 VERY COOL....So we agree on so much that the only thing left is the definition of RMS. I was under the assumption that the the measurement was taken from the start of the waveform thru the end of the waveform if it repeats or would continually average all the peaks and spaces. But I realize that you may be considering that in a waveform the beginning is when first detected and the end is when it drops from detection and we don't have to count any "spaces" that no detection takes place.
Please make a video on how to use a communication tester monitor for Amateur radio (repair) That could be a very useful for hams If possible on Rohde & Schwarz CMS50
