Homebrewing N5ESE’s Classic RF Probe

One of my viewers suggested homebrewing N5ESE’s Classic RF Probe. Though I could not source all the components exactly, I am going to try. The resistor mentioned in the circuit is 4.7 M for a DC voltmeter with input impedance of 11 M. When I tried to measure the impedance of my digital and analog multimeters with the other one, I got varying values depending on the DC voltage range chosen. All values were much below the 11 M mentioned by N5ESE. Anyway I am going to try with the 4.7 M resistor itself. Then I could not get dual sided copper clad PCB. Only single sided was available. 1N34A diode was not available and I bought 1N4148 which was available. I was told that it can measure RF voltage of 0.7V upwards while 1N34A would have measured from 0.25V upwards. Reverse breakdown voltage of 1N4148 is listed as 100V peak and 75V continuous. That will be maximum RF voltage which can be checked with this probe. Copper pipe for enclosing the circuit was available, but end caps were not! So with all these limitations, I am proceeding with a trial homebrewing.

This capacitor which I sourced from my old collection is rated for 100V (indicated by the ‘2A’) and has a capacity of 0.01 μF (‘103’ indicates 10,000 pF). The last ‘J’ indicates ±5% tolerance. It is a polyester capacitor, often called Mylar capacitor.