The measurements** above were made by Wes D. Stewart, Jr., N7WS, using a Hewlett-Packard Model 4191A RF Impedance Analyzer. The usual open-short-load cal procedure was performed (coaxial standards) and a binding post adapter was used, with appropriate electrical port extension.
The Y-axis (Rp) is in Ohms.
Rp #1 is a VHF parasitic oscillation suppressor made with Cu wire (W8JI).
Rp #2 is a similar VHF parasitic oscillation suppressor made with Ni-Cr-Fe wire (AG6K).
Rp is the parallel-equivalent resistance of the VHF parasitic suppressor. Rp is significant because VHF voltage gain is basicly equal to Rp*Mu. More VHF-Rp means more VHF amplification in an HF amplifier. Less VHF-Rp means less VHF amplification in a HF amplifier.
**Copyright 1997 by W. D. Stewart, Jr.