Vermes
Advanced Member level 4
It is a RC probe with suppression of 1:10 or 1:1 and compensation by trimmer from side of oscilloscope BNC socket. The probe tip contains a 15pF capacitor, 9M resistor and microswitch switching mode 1:1. The final scheme is the connection of tuned probe and the probe with a switch:
Passive components were soldered on a small board digested on both sides with laminate. On one side there are two resistors connected in series – they were selected to get exactly 9 Mohms. The tip was made of tailor needle, but as well you can use SMD components.
Attenuator was placed in an insulating tube of pressboard and glued into a metal tube with a diameter of 6mm from an old radio antenna. It is made of brass, so it is easy to solder the screen and mass wire with an alligator clip on the end.
The microswitch can be activated by a pusher made of a piece of plastic tube with melt ends. The whole was inserted to push into the tip of the meter and secured with shrinkable tubing. RG174 with an impedance of 50 ohms and a length of 1.0 m was used.
Plug with a bigger band was used, so that you can add a trimmer. After soldering the cable into the plug, there is a sufficient gap to fit the thin screwdriver to turn the trimmer. After making compensation, you can apply a plastic cover on the plug, which if necessary can be slided down repeatedly.
Link to original thread (useful attachment) – Sonda oscyloskopowa o tłumieniu 1:10 oraz 1:1