[Volt-nut] "HULK" Fluke 5720 calibrator rig build out of random broken boards.

[Dr. Frank]

Great idea, but please stay away from fighting one DMM against another. We're all not married with Fluke or HP. I think both meters have pros and cons. But I don't agree with your comparision Dr. Frank, but I don't want to get deeper in this discussion 

Philipp,

I still could not figure out, why and whom in particular you are indirectly calling a FLUKE or HP fanboy, especially as in this section, where metrology, not brands is in the key interest of people.
If you have me in mind, being an hp fanboy, I understand it even less.. also why you don't want to discuss that comparison further..

Or did you simply not understand, what I tried to demonstrate, that the hp 3458A due to its low tests currents (surely also due to its mediocre parallel measurement of high ohm resistance) by far can't be as good as the 8508A in its worst of three Ohm mode?

A pity that you skipped the discussion at that point.

Frank

[e61_phil]

Hi Frank,

we moved the discussion to the new thread quarks opened.

I already said there, that I read something between the lines which isn't there. Sorry for that!

And yes, I simply misunderstood you. For me it seems that you want to say something like "hey, this 3.5 digit meter is more or less like the 3458A, because you have to switch the 3458A to NDIG 3 to compare it." But that was my fault and not yours.

[TiN]

On my quest to make it real 5720A-level unit, I got some candy from RFparts.com (pleasure to deal with, I only wish their site would be less buggy    )



Bought this new revision A16 some time ago, with missing and bodged out parts, including one of RF transistors, hence the photo above.
This is power amplifier assembly, that makes 220V ranges and related functions. I have older version A16 which works fine, but we not going to settle to second best.



Somebody stole capacitors from it too.

But magical hybrid is all nice and intact, covered under plastic oven hood:



So I went ahead, put all brand new missing parts back in and plug it into the Hulk with fingers crossed. (it was already 4am or so, so no patience to check voltage rails/etc. NOT recommended way of repair!)



No magic sparks or orange smoke escape, start self-test..... PASS.... start CalCheck procedure.... all good, yay?

Connected output to my beloved 4920M, set 30VAC...



And no problem with output



Did full calibration procedure afterwards, no problem. Max change was 1610% for 220VDC range (no wonder, assembly is different).



One sleep-less night, and bingo, board is back to life.

After A11 REFDAC, this module is the largest revision change between legacy 5700A and updated 5720A units.



And here's calibration change report, for curious minds:

Code: [Select]

   
    ------------------------------------------------------------------------
    FLUKE CORPORATION             S/N :)        5720A OUTPUT CALIBRATION
    PRINTED ON  8/16/18 AT 20:33:55 xDevs.com HULK, Initial CAL
    ------------------------------------------------------------------------
    ------------------------------------------------------------------------
                                MODULES PRESENT
    ------------------------------------------------------------------------
    Software Revision 1.4+B+*
    Switching Matrix
    DC Volt Module 
    AC Volt Module 
    220V Module     
    1100V/2A Module
    Current Module 
    Ohms Module     
    Hires Osc Module
    Rear Panel     
    ------------------------------------------------------------------------
                   ARTIFACT CALIBRATION DATES AND TEMPERATURES
    ------------------------------------------------------------------------
    Specification Interval:     24hour        Confidence:     99%`

    MAIN OUTPUT:   (Most recent)   8/15/18,  22.4 Degrees C
                      (Previous)   8/01/18,  27.0 Degrees C
           (Days since last cal)  1

    ZERO:          (Most recent)   8/16/18
           (Days since last cal)  0
    ------------------------------------------------------------------------
                                 STANDARDS USED
    ------------------------------------------------------------------------
    STANDARD         NUMBER             CERT. DATE

    VOLTAGE      _FX792X______       ____07/04_______       9.999999 V

    10 kOhm      _FSL935_______       ___05/30_______       9.999976 kOhm

    1 Ohm        __FSL935_______       ___05/30_______      1.0000594 Ohm

    ------------------------------------------------------------------------
                    EXTERNALLY CALIBRATED INTERNAL REFERENCES
    ------------------------------------------------------------------------
        REFERENCE            Most Recent          Previous       Shift (ppm)
    6.5 V DC Reference          6.957491          6.957486              0.66
    13 V  DC Reference         13.855310         13.855310              0.00
    Resistance Reference       0.9999856         0.9999836              1.97
    1.0 Ohm Resistor           0.9998467         0.9998039             42.80
    1.9 Ohm Resistor           1.8999940         1.8998703             65.12


    ------------------------------------------------------------------------
                            DC VOLTAGE OUTPUT SHIFTS
    ------------------------------------------------------------------------
    RANGE Point     Zero Shift       Full Scale Shift          Spec   Shift 
                                                              (+/-) (% spec)

    220 mV +FS     0.00000 mV    -0.00014 mV  -0.65   ppm   7.27 ppm   -8.98
           -FS     0.00000 mV     0.00019 mV   0.87   ppm   7.27 ppm   11.98

      2.2V +FS   0.0000000  V   0.0000018  V   0.80   ppm   3.86 ppm   20.75
           -FS  -0.0000000  V  -0.0000013  V  -0.58   ppm   3.86 ppm  -15.09

       11V +FS    0.000000  V    0.000004  V   0.40   ppm   2.77 ppm   14.31
           -FS    0.000000  V   -0.000002  V  -0.18   ppm   2.77 ppm   -6.42

       22V +FS   -0.000002  V   -0.000002  V  -0.08   ppm   2.73 ppm   -2.92
           -FS    0.000002  V   -0.000003  V  -0.13   ppm   2.73 ppm   -4.73

      220V +FS     0.00007  V    -0.01312  V -59.63   ppm   3.73 ppm-1599.83
           -FS     0.00007  V     0.01320  V  60.02   ppm   3.73 ppm 1610.18

     1100V +FS      0.0001  V     -0.0004  V  -0.36   ppm   5.45 ppm   -6.52
           -FS      0.0001  V      0.0003  V   0.31   ppm   5.45 ppm    5.70

    ------------------------------------------------------------------------
                            AC VOLTAGE OUTPUT SHIFTS
    ------------------------------------------------------------------------
    RANGE        Point            Full Scale Shift            Spec   Shift 
                                                              (+/-) (% spec)

    2.2 mV      FS          -0.000029 mV    -0.0013 %       0.24 %     -0.57
             20.00  kHz     -0.000025 mV    -0.0011 %       0.24 %     -0.48
             50.00  kHz     -0.000032 mV    -0.0014 %       0.25 %     -0.58
            100.00  kHz     -0.000029 mV    -0.0013 %       0.32 %     -0.40
            119.99  kHz     -0.000024 mV    -0.0011 %       0.65 %     -0.17
            0.1200  MHz     -0.000013 mV    -0.0006 %       0.65 %     -0.09
            0.2000  MHz     -0.000003 mV    -0.0002 %       0.65 %     -0.02
            0.3000  MHz      0.000029 mV     0.0013 %       0.65 %      0.21
            0.4000  MHz      0.000066 mV     0.0030 %       1.28 %      0.23
            0.5000  MHz      0.000113 mV     0.0051 %       1.28 %      0.40
            0.6000  MHz      0.000180 mV     0.0082 %       1.43 %      0.57
            0.7000  MHz      0.000253 mV     0.0115 %       1.43 %      0.81
            0.8000  MHz      0.000348 mV     0.0158 %       1.43 %      1.11
            0.9000  MHz      0.000442 mV     0.0201 %       1.43 %      1.41
            1.0000  MHz      0.000587 mV     0.0267 %       1.43 %      1.87
            1.1000  MHz      0.000734 mV     0.0334 %    NO SPEC        0.00
            1.1999  MHz      0.000845 mV     0.0384 %    NO SPEC        0.00

     22 mV      FS           -0.00025 mV   -11.48   ppm   312.27 ppm   -3.68
             20.00  kHz      -0.00029 mV   -13.14   ppm   312.27 ppm   -4.21
             50.00  kHz      -0.00023 mV   -10.24   ppm   447.27 ppm   -2.29
            100.00  kHz      -0.00018 mV    -8.41   ppm   772.73 ppm   -1.09
            119.99  kHz      -0.00014 mV    -0.0006 %       0.15 %     -0.41
            0.1200  MHz      -0.00019 mV    -0.0009 %       0.15 %     -0.57
            0.2000  MHz       0.00011 mV     0.0005 %       0.15 %      0.32
            0.3000  MHz       0.00104 mV     0.0047 %       0.15 %      3.07
            0.4000  MHz       0.00082 mV     0.0037 %       0.25 %      1.47
            0.5000  MHz       0.00136 mV     0.0062 %       0.25 %      2.44
            0.6000  MHz       0.00216 mV     0.0098 %       0.40 %      2.44
            0.7000  MHz       0.00301 mV     0.0137 %       0.40 %      3.38
            0.8000  MHz       0.00410 mV     0.0186 %       0.40 %      4.62
            0.9000  MHz       0.00544 mV     0.0247 %       0.40 %      6.12
            1.0000  MHz       0.00678 mV     0.0308 %       0.40 %      7.63
            1.1000  MHz       0.00956 mV     0.0435 %    NO SPEC        0.00
            1.1999  MHz       0.01088 mV     0.0494 %    NO SPEC        0.00

    220 mV      FS            -0.0009 mV    -4.07   ppm   121.36 ppm   -3.35
             20.00  kHz       -0.0004 mV    -2.03   ppm   121.36 ppm   -1.67
             50.00  kHz       -0.0011 mV    -5.14   ppm   256.36 ppm   -2.00
            100.00  kHz       -0.0008 mV    -3.71   ppm   590.91 ppm   -0.63
            119.99  kHz       -0.0004 mV    -1.65   ppm   963.64 ppm   -0.17
            0.1200  MHz        0.0007 mV     3.36   ppm   963.64 ppm    0.35
            0.2000  MHz        0.0017 mV     7.77   ppm   963.64 ppm    0.81
            0.3000  MHz        0.0050 mV    22.61   ppm   963.64 ppm    2.35
            0.4000  MHz        0.0086 mV     0.0039 %       0.15 %      2.55
            0.5000  MHz        0.0133 mV     0.0061 %       0.15 %      3.94
            0.6000  MHz        0.0200 mV     0.0091 %       0.30 %      3.06
            0.7000  MHz        0.0274 mV     0.0124 %       0.30 %      4.18
            0.8000  MHz        0.0368 mV     0.0167 %       0.30 %      5.63
            0.9000  MHz        0.0462 mV     0.0210 %       0.30 %      7.07
            1.0000  MHz        0.0607 mV     0.0276 %       0.30 %      9.28
            1.1000  MHz        0.0755 mV     0.0343 %    NO SPEC        0.00
            1.1999  MHz        0.0866 mV     0.0394 %    NO SPEC        0.00

      2.2V      FS          -0.000006  V    -2.62   ppm    49.55 ppm   -5.29
             20.00  kHz     -0.000001  V    -0.58   ppm    49.55 ppm   -1.17
             50.00  kHz     -0.000008  V    -3.69   ppm    85.45 ppm   -4.32
            100.00  kHz     -0.000005  V    -2.27   ppm   138.18 ppm   -1.64
            119.99  kHz     -0.000000  V    -0.20   ppm   425.45 ppm   -0.05
            0.1200  MHz      0.000011  V     4.80   ppm   425.45 ppm    1.13
            0.2000  MHz      0.000020  V     9.22   ppm   425.45 ppm    2.17
            0.3000  MHz      0.000053  V    24.06   ppm   425.45 ppm    5.65
            0.4000  MHz      0.000089  V     0.0041 %       0.11 %      3.64
            0.5000  MHz      0.000136  V     0.0062 %       0.11 %      5.57
            0.6000  MHz      0.000204  V     0.0093 %       0.18 %      5.19
            0.7000  MHz      0.000277  V     0.0126 %       0.18 %      7.06
            0.8000  MHz      0.000372  V     0.0169 %       0.18 %      9.48
            0.9000  MHz      0.000466  V     0.0212 %       0.18 %     11.88
            1.0000  MHz      0.000610  V     0.0277 %       0.18 %     15.57
            1.1000  MHz      0.000758  V     0.0345 %    NO SPEC        0.00
            1.1999  MHz      0.000869  V     0.0395 %    NO SPEC        0.00

       22V      FS           -0.00002  V    -0.72   ppm    48.18 ppm   -1.49
             20.00  kHz      -0.00005  V    -2.38   ppm    48.18 ppm   -4.94
             50.00  kHz       0.00001  V     0.52   ppm    85.45 ppm    0.61
            100.00  kHz       0.00005  V     2.36   ppm   121.36 ppm    1.94
            119.99  kHz       0.00010  V     4.43   ppm   336.36 ppm    1.32
            0.1200  MHz       0.00004  V     1.96   ppm   336.36 ppm    0.58
            0.2000  MHz       0.00034  V    15.65   ppm   336.36 ppm    4.65
            0.3000  MHz       0.00128  V    58.17   ppm   336.36 ppm   17.29
            0.4000  MHz       0.00106  V     0.0048 %       0.11 %      4.32
            0.5000  MHz       0.00160  V     0.0073 %       0.11 %      6.53
            0.6000  MHz       0.00240  V     0.0109 %       0.17 %      6.49
            0.7000  MHz       0.00324  V     0.0147 %       0.17 %      8.76
            0.8000  MHz       0.00434  V     0.0197 %       0.17 %     11.73
            0.9000  MHz       0.00567  V     0.0258 %       0.17 %     15.33
            1.0000  MHz       0.00701  V     0.0319 %       0.17 %     18.96
            1.1000  MHz       0.00980  V     0.0445 %    NO SPEC        0.00
            1.1999  MHz       0.01112  V     0.0505 %    NO SPEC        0.00

      220V      FS            -0.0054  V   -24.47   ppm    60.18 ppm  -40.66
             5.000  kHz       -0.0045  V   -20.32   ppm    60.18 ppm  -33.77
            10.000  kHz       -0.0059  V   -27.01   ppm    60.18 ppm  -44.88
             20.00  kHz       -0.0068  V   -30.93   ppm    60.18 ppm  -51.39
             50.00  kHz       -0.0207  V   -94.10   ppm    95.45 ppm  -98.58
            100.00  kHz       -0.0831  V  -377.95   ppm   173.64 ppm -217.67
            119.99  kHz       -0.1258  V  -571.69   ppm   990.91 ppm  -57.69
            0.1200  MHz       -0.1243  V  -565.11   ppm   990.91 ppm  -57.03
            0.2000  MHz       -0.3558  V -1617.40   ppm   990.91 ppm -163.22
            0.3000  MHz       -0.7557  V -3434.82   ppm   990.91 ppm -346.63
            0.4000  MHz       -1.1857  V    -0.5389 %       0.52 %   -103.10
            0.5000  MHz       -1.4540  V    -0.6609 %       0.52 %   -126.44
            0.6000  MHz       -0.9597  V    -0.4362 %       0.85 %    -51.60
            0.7000  MHz       -1.6055  V    -0.7298 %       0.85 %    -86.32
            0.8000  MHz       -2.3775  V    -1.0807 %       0.85 %   -127.82
            0.9000  MHz       -1.9068  V    -0.8667 %       0.85 %   -102.51
            1.0000  MHz       -1.3834  V    -0.6288 %       0.85 %    -74.37

     1100V      FS             -0.003  V    -2.46   ppm    73.64 ppm   -3.34
            0.3000  kHz         0.003  V     3.06   ppm    73.64 ppm    4.16
            0.5000  kHz         0.000  V     0.27   ppm    73.64 ppm    0.37
            0.7000  kHz         0.001  V     1.11   ppm    73.64 ppm    1.51
            1.0000  kHz        -0.001  V    -0.68   ppm    73.64 ppm   -0.92

    ------------------------------------------------------------------------
                            DC CURRENT OUTPUT SHIFTS
    ------------------------------------------------------------------------
    RANGE Point     Zero Shift       Full Scale Shift          Spec   Shift 
                                                              (+/-) (% spec)

    220 uA +FS      0.0001 uA      0.0003 uA   1.18   ppm  71.82 ppm    1.64
           -FS      0.0001 uA     -0.0001 uA  -0.60   ppm  71.82 ppm   -0.84

    2.2 mA +FS   -0.000003 mA    0.000001 mA   0.35   ppm  33.64 ppm    1.03
           -FS   -0.000002 mA   -0.000006 mA  -2.92   ppm  33.64 ppm   -8.69

     22 mA +FS     0.00000 mA     0.00003 mA   1.56   ppm  32.27 ppm    4.83
           -FS     0.00000 mA    -0.00003 mA  -1.57   ppm  32.27 ppm   -4.86

    220 mA +FS      0.0000 mA     -0.0005 mA  -2.07   ppm  53.32 ppm   -3.88
           -FS      0.0001 mA      0.0005 mA   2.44   ppm  53.32 ppm    4.58

      2.2A +FS    0.000017  A   -0.000311  A-141.40   ppm 115.22 ppm -122.73
           -FS    0.000018  A    0.000346  A 157.26   ppm 115.22 ppm  136.49

    ------------------------------------------------------------------------
                            AC CURRENT OUTPUT SHIFTS
    ------------------------------------------------------------------------
    RANGE        Point            Full Scale Shift            Spec   Shift 
                                                              (+/-) (% spec)

    220 uA      FS              0.000 uA     0.15   ppm   165.45 ppm    0.09
            0.5000  kHz        -0.001 uA    -4.00   ppm   165.45 ppm   -2.42
            1.0000  kHz        -0.000 uA    -0.55   ppm   165.45 ppm   -0.33
             2.000  kHz         0.000 uA     1.23   ppm   368.18 ppm    0.33
             5.000  kHz        -0.001 uA    -3.23   ppm   368.18 ppm   -0.88
             7.000  kHz        -0.001 uA    -0.0006 %       0.14 %     -0.47
            10.000  kHz        -0.002 uA    -0.0010 %       0.14 %     -0.70

    2.2 mA      FS            0.00000 mA     0.89   ppm   138.18 ppm    0.64
            0.5000  kHz       0.00000 mA     1.80   ppm   138.18 ppm    1.30
            1.0000  kHz       0.00000 mA     0.92   ppm   138.18 ppm    0.66
             2.000  kHz       0.00000 mA     1.21   ppm   269.09 ppm    0.45
             5.000  kHz       0.00000 mA     0.43   ppm   269.09 ppm    0.16
             7.000  kHz      -0.00000 mA    -0.0001 %       0.14 %     -0.09
            10.000  kHz      -0.00000 mA    -0.0002 %       0.14 %     -0.13

     22 mA      FS             0.0000 mA     0.82   ppm   138.18 ppm    0.59
            0.5000  kHz       -0.0000 mA    -1.49   ppm   138.18 ppm   -1.08
            1.0000  kHz        0.0001 mA     2.57   ppm   138.18 ppm    1.86
             2.000  kHz        0.0000 mA     0.83   ppm   241.82 ppm    0.34
             5.000  kHz        0.0000 mA     0.81   ppm   241.82 ppm    0.33
             7.000  kHz       -0.0000 mA    -0.0002 %       0.13 %     -0.13
            10.000  kHz       -0.0001 mA    -0.0003 %       0.13 %     -0.24

    220 mA      FS             -0.001 mA    -3.00   ppm   133.64 ppm   -2.25
            0.5000  kHz        -0.000 mA    -1.74   ppm   133.64 ppm   -1.30
            1.0000  kHz        -0.000 mA    -0.52   ppm   133.64 ppm   -0.39
             2.000  kHz         0.000 mA     1.67   ppm   228.18 ppm    0.73
             5.000  kHz        -0.001 mA    -5.36   ppm   228.18 ppm   -2.35
             7.000  kHz        -0.000 mA    -0.0001 %       0.11 %     -0.13
            10.000  kHz        -0.002 mA    -0.0008 %       0.11 %     -0.79

      2.2A      FS           -0.00033  A  -150.08   ppm   308.18 ppm  -48.70
            0.5000  kHz      -0.00034  A  -152.39   ppm   308.18 ppm  -49.45
            1.0000  kHz      -0.00033  A  -148.33   ppm   308.18 ppm  -48.13
             2.000  kHz      -0.00033  A  -150.07   ppm   485.45 ppm  -30.91
             5.000  kHz      -0.00033  A  -150.09   ppm   485.45 ppm  -30.92
             7.000  kHz      -0.00034  A    -0.0153 %       0.61 %     -2.51
            10.000  kHz      -0.00034  A    -0.0154 %       0.61 %     -2.53
    ------------------------------------------------------------------------
                            RESISTANCE OUTPUT SHIFTS
    ------------------------------------------------------------------------
            Point             Full Scale Shift                Spec   Shift 
                                                              (+/-) (% spec)

     0.0000000  Ohm      0.0000000  Ohm   0.00   Ohm         0.00 Ohm    0.00
     0.9998039  Ohm      0.0000428  Ohm  42.80   ppm        85.00 ppm   50.36
     1.8998703  Ohm      0.0001237  Ohm  65.12   ppm        85.00 ppm   76.61
     10.000290  Ohm       0.000037  Ohm   3.73   ppm        23.00 ppm   16.24
     18.999925  Ohm       0.000051  Ohm   2.71   ppm        23.00 ppm   11.77
     100.00301  Ohm        0.00016  Ohm   1.62   ppm        10.00 ppm   16.18
     189.99756  Ohm        0.00049  Ohm   2.59   ppm        10.00 ppm   25.91
     1.0000085 kOhm      0.0000019 kOhm   1.86   ppm         8.00 ppm   23.19
     1.9000219 kOhm      0.0000035 kOhm   1.82   ppm         8.00 ppm   22.70
      9.999776 kOhm       0.000015 kOhm   1.54   ppm         8.00 ppm   19.31
     18.999374 kOhm       0.000030 kOhm   1.58   ppm         9.00 ppm   17.57
      99.99470 kOhm        0.00012 kOhm   1.16   ppm         9.00 ppm   12.92
     189.98859 kOhm        0.00068 kOhm   3.59   ppm         9.00 ppm   39.93
     0.9999808 MOhm      0.0000017 MOhm   1.73   ppm        16.00 ppm   10.84
     1.8999653 MOhm      0.0000062 MOhm   3.28   ppm        17.00 ppm   19.31
      9.998990 MOhm       0.000051 MOhm   5.08   ppm        33.00 ppm   15.39
     18.998386 MOhm       0.000109 MOhm   5.76   ppm        43.00 ppm   13.38
     100.00693 MOhm        0.00184 MOhm  18.41   ppm       100.00 ppm   18.41


[Vgkid]

Looking good.
What is the IET Labs reference resistor in the back?

[M4x]

Awesome project, thanks for sharing!

Max

[TiN]

Got some news from a bird. Missing chassis parts are manufactured and will be on their way to me soon. So excited!

.

These are internal shields for both inguard and outguard sections and exterior top and bottom covers. Yes, I ordered exterior covers with black powder coating. I think black will look much better on my 5720 Hulk edition and match my SL935 and 792X standards  .

I also could not resist getting second set of resistance boards (pun intended).



Second A9 OHM CAL (that contains calibration circuitry, reference 10K resistor hermetic network and 1.0, 1.9 ohm resistors and 4-wire short) is also 5720A version. Second A10 (working ohms PCBA) is older 5700A version (on photo it is the one with white COTO relays), which have little bit different networks and older CADDOCK 90Meg resistor.

Will be interesting to compare both boards stability, as one set will be just sitting on shelf, while second set to operate in calibrator 24/7/365. 

[e61_phil]

Is it worth buying a Fluke 5720A instead of a cheaper (and easier to get) 5700A at work? I'm especially interested in DC Volts up to 1000V.
Do you have some experience about the real differences and not only data sheet values?

[TiN]

I'd go for 5720A, it have multiple circuit updates for better reliability. Also DC linearity of 5720A is better.
High frequency AC is major improvement as well, but I did not get to testing that part yet.

Also recent 5700A are likely have most of hardware at 5720A level anyway, it's not that you can get replacement boards for 5700A anyway (by official service).
There are also 5700A series II, and 5700A/EP units, and 5700A/AF units, and few more obscure ones 

[texaspyro]

Hulk covers need to be green... otherwise Hulk gets angry, and you don't want to see Hulk get angry.   

[TiN]

My favourite delivery express guy made a visit and left me some goodies. 
From CAD drawing to reality, just like that...



Let's see how many dimensions I got wrong .



I had to make inner shields for both inguard floating cage and for outguard controller side.



Almost "Before" and "after" photo, with only difference that after is not a same part, but a DIY replacement . Despite the desire of texaspyro and others, it is not green 



I also ended up ordering custom CNC brass inserts, for captive screw mounts for inguard shield, so it would mimic original Fluke design closely. Those ended up a nice fit!



But not so much for A14 PCB notch cutouts! They are off by few mm, I guess somebody in xDevs chat got me distracted.
Dremel to the rescue, nothing can stop some shhrrr-shhrrr with cutting wheel. Not even angry neighbors next-door. 



She'll be alright, like we used to say here at EEVBlog!



There are still some little tweaks to do, but so far I'm very happy with the outcome.



In fact, calibrator already doing it's job, I just recently used it to calibrate all functions of freshly repaired 8842A, but that is a story of the other thread. 

[ManateeMafia]

Looks great. 

You can still get some decals for it.  https://www.etsy.com/market/hulk_decal

[dl1640]

Definitely a 5720B    ...

[Zucca]

Respect, and you know exactely what parts are inside. Knowing what is inside the device is much more important than the "external" stuff.

[TiN]

I need to upgrade just one high voltage board to be 100% 5720-level on hardware.

Maybe I'll do something with top plastic frame to make it more "black" 
Quick experiment with cloth tape:

[dl1640]

How is terminal shield fixed onto front panel, by screw?

通过我的 PRA-AL00 上的 Tapatalk发言

[TiN]

No, it's insert into GUARD binding post. You can see screw that holds banana terminal inside.

[TiN]

Thanks to lukier for kick in the butt, I got around to run some python snakes to measure (or should I better say, estimate?) linearity errors of the above mentioned Hulk calibrator.
So here are some pretty charts, impressed even me... Can't be that good. 

Method is rather simple, python application programs DC voltage of the Hulk output from -10.9 to +10.9, with range locked to 11V. Steps in programming are 0.1V, for good resolution. Calibrator ran internal zero before test.

As detector we use ADC with best linearity possible : 3458A. Actually two of them, connected to Hulk output, using Belden cable and bare copper spade lugs.



Then collected data points are calculated for deviation from best-fit polynom, and error calculated in ppms from 10VDC scale. Numpy code to do that:

Code: [Select]

p = np.polyfit(real,ideal,1) # Fit polynom to data
pv = np.polyval(p,real) # Calculate deviation from polynom
diff = ideal-pv # Determine delta
diff_ppm = (diff/10)*1000000.0 # Calculate scale in ppms
Some comments for less verse readers:
* Thin blue line is meter 3458A (GPIB 3)
* Thin pink line is second meter 3458B (GPIB 2)
* Thick brown line is INL data of 3458B minus INL data of 3458A. This essentially to remove INL of the calibrator source itself, to get difference between two 3458As.
* Orangle line is bonus, Fluke 8508A versus Hulk calibrator. Settings RESL8, FAST_OFF, equivalent to about NPLC1040. 

Differential INL between 3458A is quite cool +0.09 to -0.06 ppm peak to peak. Matching the 0.1 ppm specification of the 3458A well, for what it's worth. 

Then I turned off aircon in calroom, and let ambient temperature to climb +29C. Idea is that it may help INL data, by removing drafts and temperature variations?



This test still running (Beware, full sweep takes multiple hours, so not 100% correct way, as best INL specified only for minutes/tens minutes periods, not hours), that's why data not finished.

* Thin blue line is meter 3458A (GPIB 3)
* Thin pink line is second meter 3458B (GPIB 2)
* Thick brown line is INL data of 3458B minus INL data of 3458A. This essentially to remove INL of the calibrator source itself, to get difference between two 3458As.
* Orangle line is bonus, Fluke 8508A versus Hulk calibrator. Settings RESL7 this time, FAST_OFF, equivalent to about NPLC104. 
* This graph also have Keithley 2002 meter added for giggles. NPLC50, DFILT OFF.
* Bold magenta and violet lines are difference of K2002 from either of 3458s.

As sanity check, I got remote access to <90day calibrated Fluke 5730 in far far away galaxy. So I ran very same code on 5730A and 3458A (another one, not mine) so we can glance over the data from this setup as well.

10V , NPLC50. Same configuration of the calibrator as my 5720A Hulk.



1V range, NPLC 100. Rangelock at 2.2V range.. Otherwise same configuration.



Comments?

[GigaJoe]

Comments?

Mmm ... , well ...,  it seems OK,  Right?

[CalMachine]

Lookin good! 

You should compare tests with Fluke 720A, as well

[Kleinstein]

It still looks like there is a small jump at around 0 V, when the 5720 reverses polarity. AFAIK this is done with relays, so that except for a possible jump at around zero the 5720 should be to a large part be symmetric. A possible additional test could be with the voltmeter(s) in revers connection.

So the calibrator looks really good - except for that small jump around 0.  With a careful measurement, one might be able to correct some of this in software.

As the run seems to take quite some time, there might be a temperature effect too. To see this a second run under similar conditions could help. Its kind of finding a compromise between speed and noise.

[TiN]

Yes, polarity reversal in 57xx done by relay on the output of the DAC.
I don't sweat much about that jump, it's 0.2ppm after all. Own noise of the DMM's reference is that much anyway. It is not that often that you need transfer negative voltage to positive voltage.

A possible additional test could be with the voltmeter(s) in revers connection.

Interesting idea, i'll try. Also will add 3458C into mix (third meter that have 2ppm/hour drifty ADC), curious to see if drifty ADC also have bad linearity.

As the run seems to take quite some time, there might be a temperature effect too. To see this a second run under similar conditions could help. Its kind of finding a compromise between speed and noise.

I did fast test with same rig but using NPLC10 instead of NPLC100. 8508A in RESL6 mode, and its linearity goes to toilet in this mode, unlike 3458A@NPLC10.

[e61_phil]

I did fast test with same rig but using NPLC10 instead of NPLC100. 8508A in RESL6 mode, and its linearity goes to toilet in this mode, unlike 3458A@NPLC10.

I think that is a quantization problem. If you select 6 digits on the 8508A you will get only 6 digits instead of the 3458A which gives always a billion digits over GPIB no matter how it is configured.

[TiN]

Quantization or not, as result you can't get good linearity out of 8508A without making it slowest meter on the planet  .

[e61_phil]

Quantization or not, as result you can't get good linearity out of 8508A without making it slowest meter on the planet  .

Yes, both meters have pros and cons. And speed is definitely a point for the 3458A

[Dr. Frank]

I'd like to point to similar linearity measurements, I've done, 3458A vs. 5442A:




I made 8 runs, always one direction on the 5442A, say from -11V to +11V, but also with reversed leads, so to measure the positive voltages of the 5442A as negative inputs on the 3458A, and vv., and afterwards mirroring the results in xls.

You see, due to this delicate measurement, you'll always get different results, mostly shifted values, but sometimes also qualitatively different.

So to really make good statements, maybe also quantitatively, it is required to make several runs, best would be circular ones (-11.. +11 .. -11 ...).
These singular measurements with 3458A, 5720 and 8508 may not reveal the whole story, I expect all instruments to perform a bit better in reality.
Especially the 3458A vs. 3458A should improve.

Frank