Finally, I received the attenuator set for the HP 8662A repair. The very special 5+40+40 db attenuator with a side connector (rather than the usual design of these attenuators with two top SMA connectors).
However, a quick test showed that the 5 dB step is not working right. The “through” path is fine, but when I engage the 5 dB attenuator, is is something like 45 dB, unstable. Maybe a blown segment? That would be an easy fix.
So, I opened it up carefully, and found a broken contact. It seems the side connection is pushing a bit on the contact, and over the year, this design caused the plastic to fail. Tough to fix without precision drills and machine tools. So it will need to wait for the virus to clear, and for me to go to the German workshop again, to attempt an repair.
There are two small plastic studs, and they broke off, maybe the plastic got brittle over time with the pressure of the side contact pushing.
Let’s think about how to fix it, if at all possible.
Note – the seller was kind enough to refund half of the price, without having me to ship back the part, fair enough. At least some spare coils and segments should I need to fix other attenuators in the future.
2 thoughts on “HP 33321SB aka 33321-60026 Attenuator: HP 8662A Synthesized Signal Generator fix”
I was able to repair an attenuator (HP 8495A) with this exact problem. I used a 1.0 mm PCB drill bit to hand drill two holes into the plastic block at the broken-off stud locations. I drilled the holes at slight angles away from each other. I then filled the holes with UV activated glue, placed the contact onto the block and applied more UV glue on top linking the holes together. After carefully aligning the contact a UV light was used to cure the glue. After several months, the repair seems to be holding up nicely
Thank you, it sounds like something I would like to try, only that in my workshop here in Japan I have no drill presently, but once back in Germany there is coule work fine. I fixed it so far by cutting of a piece from a working donor attenuator, will post it soon. So far I have several unneeded donors, but would like to fix it as you did at least for the lower ghz uses, or test it on the vna afterwards.