I`ve been thinking of getting a GPIB controller for quite a while (since shortly after I started collecting old HP test equipment). I`ve tried to use an IOTech serial GPIB controller, but with very limited success. Finally I saw a used Prologix controller on eBay, so I ordered it. I was delighted to finally be able to use the KE5FX GPIB toolkit to capture images from my HP 8566B...but the excitement was short-lived. The next day, I tried to connect to another instrument, but nothing worked. I tried everything I could think of, but nothing worked. Both the GPIB configurator and EZGPIB reported no communication with the Prologix controller, but the FTDI USB controller inside it was enumerating on the bus, so something had gone disastrously wrong.
I contacted Prologix to ask about the possibility of getting repair parts, but they just told me to send them the defective unit. After they received it, I got an email back:
And a plot from the 8756A of a crappy over-coupled 4.5GHz filter I threw together:
I contacted Prologix to ask about the possibility of getting repair parts, but they just told me to send them the defective unit. After they received it, I got an email back:
Hello Mark,
We have received the defective unit. Upon inspection we found that it wasn’t a genuine Prologix unit, but a counterfeit clone manufactured in China.
However, since we want you to be a happy Prologix customer we will send you a genuine replacement at no cost.
So that explains the early failure! I didn't think anyone would counterfeit Prologix controllers (being such a niche market), and they must have gone to considerable lengths to match the external appearance of the genuine units. There were no obvious give-aways that this wasn't the real thing (unlike the ``Noth Frace`` clothing on sale in Kathmandu).
I received the genuine replacement unit about a week ago, and have been putting it through the paces with my 8566B and 8756A. Here`s the HP 8566B with Harmonic lock turned on, set at harmonic 4 (which enables coverage up to 25GHz, yay! I can finally see the output of my 24GHz Gunn oscillators!)
I was hoping that my filter would behave more like this 10GHz waveguide cavity filter (though even it has a few spurious responses just off the passband):
I also learned that if I get an appropriate external harmonic mixer, the 8566B can go well into the millimeter-wave range:
But most of all, I'm happy to finally have a GPIB controller that works! Thanks Prologix!
-mark.
(I was thinking of using `Beware the Attack of the Clones` as a title for this post, but I think that would just be too ugly....)
