Use of the Kirkby Microwave calibration kits on the Agilent/Keysight 8719 (13.5 GHz), 8720 (20 GHz) or 8722 (40 GHz) VNAs.

HP 8720D vector network analyzer

Much of the development of the kits were performed with the aid of an 8720D, so this analyzer is well known to us.

Entering calibration kit definitions into an 8719, 8720 or 8722 series instrument.

It is absolutely essential that a VNA has the correct calibration constants for a calibration kit. Using any Kirkby Microwave kit with the default calibration kit will result in incorrect measurements. They might look fine, and show a nice flat S12 and S21 of close to 0 dB, and an S11 and S22 of -60 dB or better, but the results of any measurements will be incorrect.

Depending on model, three or four of these methods will work.

  1. Using a floppy disk. This is the easiest way, but obviously only works on models that have internal floppy drives.
  2. Loading via GPIB using the Cal Kit Manager 2.1 software. This software, available from the Keysight website, allows the coefficients to be loaded fairly easily, but there can be some compatibility issues between the software and some GPIB controllers.
  3. Loading via GPIB using other software. This method will be useful if your GPIB controller and the Cal Kit Manager softare will not work together.
  4. From the front panel. This method works on any model in this series and does not require any other software or hardware. However, it is a bit tedious, and easy to make an error.

Method #1 - Using a floppy disk

Using a floppy disk. If your VNA has an internal floppy disk drive, Kirkby Microwave can supply suitable floppy disks if we are made aware the kit is to be used with an instrument with a floppy disk drive. If you did not request a floppy disk when ordering the kit, or have lost the disk, then you can download a zip file from our website. Which file you downloads depends on what kit you have. Just unzip the files to a 1.44 MB 3.5 inch floppy disk. Each calibration kit definitions will have several files with the same prefix, but different suffices. You can use a USB based floppy disk drive. You can put multiple kits on the same floppy disk. Once completed, you should ensure the disk is write protected by moving the little tape so daylight can be seen in the hole.

At this point, assuming your floppy drive still works, you should get a list of the files on the floppy. Pick the one for the kit. The name should be obvious. For example, for our SMA kit, it will be SMA or KM85033. For the N kit it will be KM85054. For other kits, the names should be obvious. You can store multiple kits on the same disk. Each entry has several files, which you can see on a PC, but will not see on a VNA.

that will then load the coefficients into the USER kit. When the VNA is powered off, assuming the supercap (early models) or battery (later models) is ok, the contents of the user defined calibration kit will be stored. There should be no need to load them again. Note however that when the instrument is rebooted, either via pressing the PRESET button or by powering it off, the calibration kit will revert to the default for that instrument.

Method #2 - Use the Cal Kit Manager 2.1 software

The VNA Cal Kit Manager 2.1 software is desgined to connect to many VNAs, including the 8753, 8719, 8720 and 8722, using GPIB. It needs a National Instruments or HP/Agilent GPIB controller. There are reports this software does not work with recent National Instruments USB GPIB controllers. The procedure to use is:

  1. Download the .ckm file for your kit from our website.
  2. Install the Cal kit Manager 2.1 software.
  3. Follow the instructions in the software

Method #3 - Writing your own software to upload the coefficients.

If you look at the programming manual for the VNA, you will see that there are various commands to set up calibration kits. Below are a list of commands which were used to set up a custom calibration kit.

CALKN50; MODI1; DEFS1; STDTSHOR; OFSD 4.1398E-11 ; OFSZ 5E1 ; OFSL 2.2E9 ; MINF 0E0; MAXF 7E9; STDD; DEFS2; STDTOPEN; OFSD 3.96E-11 ; OFSZ 5E1 ; OFSL 2.2E9 ; C0 7.1252E1 ; C1 -1.19 E3; C2 -1.10417E2 ; C3 -9.64691E-1 ; MINF 0E0 ; MAXF 7E9 ; STDD; DEFS7; STDTSHOR; OFSD 5.7834E-11 ; OFSZ 5E1 ; OFSL 2.2E9 ; MINF 0E0 ; MAXF 7E9 ; STDD; DEFS8; STDTOPEN; OFSD 5.51E-11 ; OFSZ 5E1 ; OFSL 2.2E9 ; C0 5.80514E1 ; C1 5.80271E3 ; C2 -2.51433E3 ; C3 2.01427E3 ; MINF 0 ; MAXF 7E9 ; LABK "SMAnew"; KITD; SAVEUSEK;

Method #4 - From the front panel.

If possible, it is much easier to enter a calibration kit via GPIB or a floppy disk, but if you don't have that facility, then you must define it manually. The manual for the VNA needs to be consulated carefully, but an outline of the procedure is given below, where on modifies one of the internal kits and saves it as a USER kit. That is much easier than trying to define the kit from scratch. By re-defining a suitable calibration kit, you can avoid having to worry about CLASS ASSIGMNMENTS, and only concern yourself with changing the standard definitions. So an outline of the procedure is as follows. These photos were taken from an HP 8720D VNA with 7.74 firmware, but an 8753ES with the same firmware versions shows almost identical behaviour. Different VNAs and different firmware versions might change the menu structure a little, but this should indicate the process.

  1. Press PRESET on the front panel, to get the VNA into a known state. When the instrument is preset, the default calibration kit for the instrument will be loaded. The default calibration kit for that instrument which might be something like:
  2. Press CAL on the front panel. You should see the normal calibration screen. One part of the screen should show the currently loaded calibration kit, which, as stated above, will be the default kit.
  3. Press the soft key to the right of the 'CAL KIT [ ]', as we want to change from that default kit to something else.

    VNA screen after CAL button pressed

  4. Press the soft key to the right of 'SELECT CAL KIT', which is circled in red.

    Chance to select a kit

  5. You should now see a list of calibration kits. One, the default kit, in this example an 85052 series kit, will be underlined, as shown. Change the calibration kit to one of either 'N 50 Ω 85032B/E' (on an 8753) or 'N 50 Ω 85054B' (on an 8719, 8720 or 8722). Do not use the 85032F kit if its in the firmware. Even though the 85032F is is an N kit, it is not a good choice to modify for our purposes.

    Default is 85052 series kit

  6. Once an N kit is selected, press the soft key for 'RETURN'
  7. Press the soft key for 'MODIFY [N 50]'

    modify the N calibration kit

  8. TO BE CONTINUTED

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