Products > Test Equipment

HP 3245A universal source refurbishment and upgrades

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deepfryed:
Yeah good idea re. plotting the INL, will do that.

PartialDischarge:
Analog has the ADHV4702-1, +-110V supplies , with 1mV offset and an impressive 170dB of open loop gain, so it seems to be very precise and apt for a x10 gain circuit.  Also not expensive.



https://www.analog.com/media/en/technical-documentation/data-sheets/adhv4702-1.pdf


The evaluation board is 200€ and even includes a bipolar flyback converter :  https://www.analog.com/media/en/technical-documentation/user-guides/eval-adhv4702-1cpz-ug-1444.pdf

Kleinstein:
One point worth noting is some 5 µV of offset and slightly lower scale factor for the 34401. After that there is not really much difference left.
The main type of INL expected for the PWM type DAC of the 3245 is a square contribution from a mismatch in switch resistance. There is not much seen of this. So the DAC looks OK with a good match (or a correct working numerical correction).

The data are essentially testing the relative INL - a plot may be easier to see than the raw data. Still it looks like well in specs of both instruments.

alm:

--- Quote from: Kleinstein on October 26, 2023, 01:57:18 pm ---The data are essentially testing the relative INL - a plot may be easier to see than the raw data. Still it looks like well in specs of both instruments.

--- End quote ---
I agree the data is pretty much what's necessary for INL (in the positive quadrant), except you would subtract a linear fit and report the differences instead of absolute values.

deepfryed:
I finally got around to replacing most of the electrolytic caps except the massive 8300uF 35V axial on the A6 outguard power supply board. I up sized some of them and most of the replacements are higher voltage spec'd 105c temperature rated rubycon or panasonic parts. Also replaced the RIFA mains capacitors.

Since I was doing all of this, I also replaced the elec. caps in my 34401A's. One interesting thing I noticed is that the settling time has drastically reduced in both the DMMs and the 3245A. It used to take a couple of hours previously before I could get the last digit to settle down in all of them, now it's about 20-30mins and the 3245A seems to more accurately agree with my 34401A's, one of which was calibrated a while back.

I'm going to let them all stay on overnight in a room with reasonable stable temp ~25c +/- 2c and do some measurements tomorrow. 


Attaching the replacememt parts list I used if it's of use to someone else.

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