Some time ago I purchased an old Agilent PDN to replace my 1970s HP8754A. While I was familiar with the the 8753, I was wanting something newer. While it's not a bad VNA and certainly out performs my old HP8754A in every way, the lower frequency is limited is 300kHz making it useless for measuring PDNs. The UI is alright but some parts of how it drives are cumbersome. On the plus side, interfacing it with LabView is no problem over Ethernet.
They do offer a TDR option for it but the price far exceeds the value of the VNA. Of course with LabView, adding TDR (or pretty much anything else) is not a problem.
Hopefully we will continue to see the prices on some of this older equipment come down for the hobbyist. Attached is a document talking about the design goals for the PDN and comparing it with the 8753 series.
These are a few of my notes:
The PNA uses the 33321-60056 70dB attenuators.
Administrators Username Password: Admin/agilent for newer systems
Older units use: blank or tsunami
Agilent has some notes about modifying the OS for the PNA!!!
The disk controller does not handle inverting the IDE jumpers. The original Fujitsu MHV2040AH requires no jumpers to become a master. If a replacement drive does require a jumper, it must be installed before the cable. Snip the pins and jumper!!!
The first partition is NTFS, the second FAT32. They use Ghost to image the drive. After using Drive Image to image the drive, use MBRWORK to copy the first track of the original drive. Then save this to the SSD.
There appears to be a level shift at each bands switch point. Insert a thru, set the center to the switch point with a 2MHz span. Measure difference of the two sides.
Band Level shift error
10MHz 0.070
748 0.007
1500 0.020
3000 0.150
4500 0.175
Calibrate the unit, replace the thru with an attenuator and measure the level shift
10MHz Thru 0.00dB
10dB 0.1dB
20dB 0.12dB
30dB 0.11dB
Measuring S21 and using the spectrum analyzer to measure Port 1, it appears flat. Injecting a known good signal into Port 2, then moving the signal +/- around the band's switch point, we see the level shift. This is a design limitation and appears to the a non-linear behavior in the receivers. Looking at S12, we see the same problem.
See Caesar's comments attached.
I have also attached the FAQ from Keysight.
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Added some other possible notes that I found in the KeySight forums.
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When I was looking, I had came across a matrix of various VNAs. I had thought about buying that PicoVNA but after downloading at trying the software, I decided to go with a used system.