Test Equipment Center, Inc. HP A Specifications. HP A products for sale at Test Equipment Center are thoroughly tested, and receive electrical and cosmetic reconditioning as needed prior to sale. All products include a 90 day warranty from Test Equipment Center to ensure your complete satisfaction. We Buy Test Equipment!
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Welcome, Guest. Please login or register. Did you miss your activation email? This topic This board Entire forum Google Bing. Print Search. I must say that I am impressed with the build quality of these old HP meters: sturdy metal chassis, quality PCBs with gold plated traces, very accurate taut band meter movement and easy to service as all panels can be removed. Meter movement is calibrated to better than 0. It is worth reading how they did it in the HP service note. All in all a very nice piece of test equipment.
Now, my problem is how to calibrate it. I have access to the following: HPA 6. My model 29 is un-calibrated. Calibrating the A to frequencies below 1MHz will not be a problem, but I want to calibrate it all the way to 10MHz.
The Tekway DSO has sufficient frequency response but poor amplitude accuracy. The HPA has very good accuracy, but poor high frequency response. Looking for suggestions on how to proceed. Wavetek 29 DDS. The following users thanked this post: sgi Hi ED Replacing the faulty electros had a significant impact on meter linearity and accuracy. Low frequency performance is easy to check with my current gear. Better get that sorted properly too before going the full cal route and possibly..
Kleinstein Super Contributor Posts: Country:. For the 1 MHz range the scope should have a relatively flat frequency response.
I don't expect compensation points in this range. In the A I would expect the input divider and amplifier to be critical parts that can have some frequency dependence. One should be able to check the compensation by looking at the response to a square wave signal e.
Quote from: Kleinstein on November 17, , am. Quote from: Electro Detective on November 17, , am. There should be no significant difference between the direct scope input and the probe. Maybe use bath cases to check consistency. Capacitive loading e. The following users thanked this post: enut Hi enut11, I did some tests for you with my HP and also the following measuring equipment.
That did not give the expected results this function no longer works well at the higher frequencies. After the scope indicated that the Siglent generator was very flat to 40MHz I started measuring with one of my favorite measuring instruments, the Fluke A RMS meter.
Up to about 30MHz this meter also indicated that the Siglent is very flat. After warming up the HP and setting the "0" dB level 0. Regards, Bram. The typical -3 dB bandwidth of a A should be around MHz. Successfully calibrated mine using a A voltmeter, Tek A o-scope with a 7A26 amplifier, and my HP B with option as a signal source.
With that I was able to mostly replicate the manual's cal procedure and the unit seems to be spot on now. I don't have access to a signal source that can provide anything like Vrms so I just left that part alone as I doubt I'll use that range often.
Thanks blackdog, those are very impressive figures for your ! I will do that and see how it works out. I am wondering if better quality cables would result in a better calibration?
HP Cal setup. I just replaced the 1m BNC 90pF with 0. Can I put another 50ohm load simultaneously on the input. Seems wrong to me. Getting the correct measurable HF signal into the is proving to be a challenge, but non-the-less interesting. Next step is to try even lower capacitance leads. It took me a little while to realise that a Keithley was effectively increasing the meter level shown by my HPA when I was checking HP performance down at the sub-1mV level once.
And yeh, I only had kHz performance meters for cross-checking the HPA's frequency response. My HP A has a Nuvistor as an input stage with a bootstrap to keep the input impedance as low as possible over a large frequency range. This input stage is a really nice design from HP! The measured value at 20MHz was about -3dB and the input capacity has an influence of about -1dB at this frequency.
The -1db should be subtracted from the -3dB and the meter is actually -2dB at 20MHz. Above 5MHz, the cable capacity can cause a lot of inaccuracy, just like the input capacity of the HP It is always wise to take into account the variables that occur in the measuring system. You can also make a probe that can handle the 40pF input capacity of the HP Maybe you can even convert a scoop probe so you have more bandwidth at the probe tip.
You may lose 20dB of signal 10x but if the signal is large enough, this will not be a problem. Kind regards, Bram. Gyro Super Contributor Posts: Country:. Quote from: blackdog on November 18, , am. Chris "Victor Meldrew, the Crimson Avenger! Quote from: enut11 on November 18, , am. Thanks macboy. That is very handy information. I had not previously fully understood cable loading and its impact on signal levels. Hi Gyro, You're right, I really looked over that regarding the input impedance when you get below 1V.
There was an error while thanking. SMF 2. EEVblog on Youtube.
3400A RMS VOLTMETER
The lowest-priced item that has been used or worn previously. The item may have some signs of cosmetic wear, but is fully operational and functions as intended. This item may be a floor model or store return that has been used. See details for description of any imperfections. This makes it superior to conventional analog and digital voltmeters where regular analog meters top out at 3 or 4 Mhz and where DVM's often top out at Khz.
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HP 3400A RMS Voltmeter Hewlett Packard 3rd Generation AC