RG-174 is well suited for this task because of its small diameter and flexibility. Twist the wires together. The RF probe is a charge pump. The peak crest value of a signal is stored in the stray capacitance of the coaxial cable. The stray capacitance of the cable is about 50 pF. The 50 pF capacitance of the cable, and the 10 mega-ohm input impedance of an FET VOM implies a DC filter time constant of 500 m Seconds, Accurate measurements are possible at frequencies as low as 100 kHz.
Noticeable errors occur at low signal levels because of the forward bias drop of the diodes.
Assume a total diode voltage drop of about 0.3 volts. Expect more circuit loading effects, and an increase in the probe's lower cut-off frequency. For the other end of the cable. Coupling and DC blocking capacitor. Visit your friendly hardware store inch heat shrink tubing 1 in.