Back in the mid-90's I used one of these for a project and really liked it. Was sad when the day came to return it.
In '08-'09, during the economic downturn, I bought two of these MS420K's on eBay for a song, both were guaranteed to have issues, and the price reflected that. The seller was so anxious to get rid of them he offered me free shipping if I took them both (these are heavy beasts). On arrival, they both acted similarly when powered on - fans turned, no display, one didn't respond to key presses. I set this one aside and got the other one running but its crt proved to be too weak to use. Eventually I set them both aside and forgot about them.
A couple months ago, I decided I want a VNA to do PDN measurement and other impedance analysis, hopefully up to 10MHz. I decided to open this one up and see what its problems are. If you're not familiar with these older Anritsu's, the build quality is impressive. This one was clean as a whistle inside. It's prior owner did some pretty dumb things to it. It had signs of having been intentionally sabotaged. DC supply wires neatly snipped. They didn't have a key for the on-off switch, so they cut the mains wires and hardwired it on. The crt circuits were WAY out of adjustment, as if purposely; the image never came on-screen! And some calibration pots were full-on and full-off, which in practice is rarely the case. Anyway, over the last couple months I've sorted it out in my spare time, and finished the calibration last night.
And now we have a fully functional VNA. Crt still has an issue; it cold-starts off-screen, but at least now it centers and stabilizes when warm. I can take my time troubleshooting that issue.
First up is to evaluate some isolation transformers for the impedance project. It is the perfect tool for it.
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