Hi
I just acquired some of these HP meters, which look similar to the 400 series AC meters, however they have BNC inputs on the back and 3 pin miniature power connectors-photos attached
I have searched the web and HParchive, but no joy
anybody have a clue as to model number etc?
Thanks
Peter
I just acquired some of these HP meters, which look similar to the 400 series AC meters, however they have BNC inputs on the back and 3 pin miniature power connectors-photos attached
I have searched the web and HParchive, but no joy
anybody have a clue as to model number etc?
Thanks
Peter
Attachments
It's a 400 series there is EL/FL and GL they are a good instrument and wide band the EL is 10Hz to 10MHz. Used one a lot years ago in the Cal lab.
It has a linear movement and 1 mV minimum so that would match a 400E. It looks like it was part of some test system which would explain the unusual layout of the connections.
HP400E http://bama.edebris.com/manuals/hp/400e/ or http://www.jamminpower.com/PDF/HP/HP 400E.pdf They are excellent instruments with a really long service life.
HP400E http://bama.edebris.com/manuals/hp/400e/ or http://www.jamminpower.com/PDF/HP/HP 400E.pdf They are excellent instruments with a really long service life.
@1audio- thanks for the reference.
Yes I think you are correct that they were part of a system. One of the units (I have 4 of them) has some USAF markings on the front and a "Don't measure mains voltage" sticker on it- photo attached.
So given this I am wondering what voltage was intended fore the 3 pin power sockets? - (I have natural tendency to not creating magic smoke)
There is a transformer (T1) and some diodes which suggest AC to DC conversion, but I am wondering if the AC voltage was considerably lower?
Peter
Yes I think you are correct that they were part of a system. One of the units (I have 4 of them) has some USAF markings on the front and a "Don't measure mains voltage" sticker on it- photo attached.
So given this I am wondering what voltage was intended fore the 3 pin power sockets? - (I have natural tendency to not creating magic smoke)
There is a transformer (T1) and some diodes which suggest AC to DC conversion, but I am wondering if the AC voltage was considerably lower?
Peter
Attachments
Assuming the power transformer is still present, the connector is probably AC power, line, neut and gnd. You need a manual confirming the part number on the transformer is the same. HP gear normally works on 120 or 240VAC with appropriate settings. Some will work on 50/60 and 400Hz. You can try 120 VAC 60 Hz and see.
Hewlett Packard "C" modifications are those that generally affect mechanical and cabinetry aspects of a unit and not electrical specifications like the "H" series modifications. I agree with it being a system meter. But not a 400E because the inside picture (post 4) is that of a model 3400A TRMS AC voltmeter. The lower part of the meter scale is also indicative of a 3400A.
Last edited:
The 3400 is a really nice TRMS meter. You were fortunate. The only question would be the power transformer setting. The HP3400 manual should help. 3400A RMS VOLTMETER [Obsolete] | Keysight
@Hollowstate and @1audio- thanks for finding the model and service manual. The transformer is marked 9100-1440- for which I will now try and find the specifications
Suggestions if you can't specs for the power transformer:
Once you're satisfied you know the expected internal supply voltages from similar service manuals, you could use a Variac to bring raise the applied voltage gradually.
Lacking a Variac, you could safely power with a filament transformer (6 or 12 V) and measure the unknown transformer's secondary voltage. Then you'd know with certainty the appropriate line voltage.
Good luck! Sounds like a great acquisition!
Once you're satisfied you know the expected internal supply voltages from similar service manuals, you could use a Variac to bring raise the applied voltage gradually.
Lacking a Variac, you could safely power with a filament transformer (6 or 12 V) and measure the unknown transformer's secondary voltage. Then you'd know with certainty the appropriate line voltage.
Good luck! Sounds like a great acquisition!
Some help:
The part number is the standard part for that meter. It has 2 primarys for 120/240V service. You should be able to figure out its connections pretty easily. If you have several I'm sure there are takers on eBay.
I have a 3403 so it would be redundant for me but for someone who needs the TRMS features those would be great. And yours are possibly full mil-spec. judging from the connectors. However for the lack of labels maybe not.
From the mil-spec parts world:
It seems that was part of some Navy missile systems. I found this:
5950-00-405-3678 Manufacturer
MFG SKU CAGE Manufacturer Type Status Role
03400-68701 1LQK8 Agilent Technologies Inc. A A
03400-68701 28480 Hewlett Packard Co. A A
9100-1440 28480 Hewlett Packard Co. A A
From HP tech briefs 1982:
34OOA RMS VOLTMETER
3400A-11. Serials 1218A23475 and below. Rewrnmended transformer replacement kit 03400-68701
for older instruments.
The part number is the standard part for that meter. It has 2 primarys for 120/240V service. You should be able to figure out its connections pretty easily. If you have several I'm sure there are takers on eBay.
I have a 3403 so it would be redundant for me but for someone who needs the TRMS features those would be great. And yours are possibly full mil-spec. judging from the connectors. However for the lack of labels maybe not.
From the mil-spec parts world:
It seems that was part of some Navy missile systems. I found this:
5950-00-405-3678 Manufacturer
MFG SKU CAGE Manufacturer Type Status Role
03400-68701 1LQK8 Agilent Technologies Inc. A A
03400-68701 28480 Hewlett Packard Co. A A
9100-1440 28480 Hewlett Packard Co. A A
From HP tech briefs 1982:
34OOA RMS VOLTMETER
3400A-11. Serials 1218A23475 and below. Rewrnmended transformer replacement kit 03400-68701
for older instruments.
Don't be too concerned with the power transformers. Like most HP trannys they seldom caused trouble. What you should be concerned with is if the meters work correctly. The 3400A has two possible problem areas. The photo chopper and the matched pair of thermocouples in the amplifier feedback loop. The old original choppers were big bricks. Yours, by the serial number, should be the smaller style chopper mounted on the center green fiberglass board. The late versions of this meter had a solid state chopper (chip) with two adjustments on the board instead of pots mounted on the inside chassis. This late chopper board was sometimes retrofitted on earlier models. Symptoms of a defective chopper can be excessive meter jitter or only ½ scale readings on all ranges. The thermocouples can be damaged by overload. Symptoms of a bad thermocouple would be a pegging meter or one that is very sluggish. And if you do get one working well, mount a BNC connector on the front panel with a short piece of wire to the input circuit. No need of shielded wire since it's very near the input. Or just remount the TNC connector to the front and use an adapter.
Thanks @HollowState and @1audio
I tracked down a manual HP 03400-9008 which lists the 9100-1440 Transformer as T1- and matches the serial number prefix 1218. So I will check the components on the PS and if they are the same and if so bring a unit up on my Sencore PR 57.
the link for the manual is:
http://www.introni.it/pdf/HewlettPackard - 3400a Rms Voltmeter.pdf
I gained 4 of these in a job lot with a plan of getting two of them working well as reference meters for measuring AC signal.
Any suggestions on what is the type of mains connector on the back?- I think I will put in an IEC socket if it will fit- but my mechanical skills are limited.
Thanks for the heads up on the chopper and thermocouple, I will report back with what is installed
best regards
Peter
I tracked down a manual HP 03400-9008 which lists the 9100-1440 Transformer as T1- and matches the serial number prefix 1218. So I will check the components on the PS and if they are the same and if so bring a unit up on my Sencore PR 57.
the link for the manual is:
http://www.introni.it/pdf/HewlettPackard - 3400a Rms Voltmeter.pdf
I gained 4 of these in a job lot with a plan of getting two of them working well as reference meters for measuring AC signal.
Any suggestions on what is the type of mains connector on the back?- I think I will put in an IEC socket if it will fit- but my mechanical skills are limited.
Thanks for the heads up on the chopper and thermocouple, I will report back with what is installed
best regards
Peter
No, that's not the chopper board. It is the input impedance converter board with a 7586 nuvistor tube. They all have that shock mounted board. The chopper board is on the top side center. Just behind the meter. Shoot a pix of that and I'll let you know what you have. From the pix in post 4, you may have the newest style, at least on one, because I think I see a blue trim pot there.
OK, the first two pictures show the chopper board well. It is the rectangular metal box on the green board directly behind the meter. And it's the "small" type that is normally used with a 1218A serial number series. But I "think" that the middle picture in post #4 is a different 3400A then the pictures above. Look at them all and see if the boards are the same or not.
thanks- yes they were two different units, I will check all four to see what is what- much appreciated @HollowState