Electronics > Repair
Boonton 41-4B power sensor repair advice
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Kosmic:
Like I said, I used Canare L-2T2S in the past. Was working fine and did not notice any differences, even at -60 dBm.

I remember looking around and never found a double shielded cable like that.
xrunner:
I removed all the components from the center pin. I took the opportunity to remove the input hardware and clean them up.

When the solder is melted on the top on the center pin, all the components touching it slide around. This because the chip capacitor acts as an out-of-control force pushing in various directions as it will making it nearly impossible to work on individual components in that area. In order to hold things down, I made up a little assembly to press the chip capacitor down while the solder is melted, so I can solder two diodes and two SMD resistors in accurate positions.

I have a little bit of material coming that I want to use in concert with the SMD resistors, so I'll get to that soon.
xrunner:
Here's my plan. I got some 0.1 mm thick copper sheet and cut off a strip with a width equal to a 1206 SMD part (0.06 "). I'm making a connection point with "wings" for the 1206 100 ohm resistors that doesn't require soldering directly on the pedestal. Trying to get all the components soldered in the right place without disturbing other components already there is too difficult with the parts I'm using. With this I can tack the SMD resistors on to the wings without melting the center area.

So I first soldered the copper wing with chip capacitor on top while being pinned down. I checked the capacitance afterwards to make sure it was correct. Now the center area does not again have to be completely melted. I can tack on the SMD resistors on the wings and then tack the diodes on top of the chip capacitor quickly, without the whole area melting.

Anyway that's my solution, others may come up with different ideas based on the physical construction of the components being used.
xrunner:
Today I installed the two 100 ohm 1206 size resistors using more copper strips. They have a little bend in them so the assembly has a just a little flex in it.
edpalmer42:
Do you have access to a VNA?

It would be interesting to see what the impedance of your rebuilt probe looks like compared to an official one.  I think that's the purpose of the offset washers that the resistor leads were clamped under.  By turning the washer you could tweak the termination.

Ed
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