Antenna coax must be momentarily shorted before each use, or damage may occur to the MFJ269 Antenna Analyzer.
Simple impedance check: use an accurate SWR meter and divide Zo, 50 ohms, by the SWR. Do not use this method unless Xs reactance is very close to 0 ohms, if antenna Z is greater than Zo, or if SWR is very high. Antenna load should be resistive only. For more information about formulas used in the calculations below, see: Radio Electronics Formulas
Run each test several times. Tests can be inaccurate due to nearby metal structures or elements, as well as other conditions, including strength of the mag
mount, earth ground, etc.
½ Wave Length Inverted VEE – Apex angle 90º
½ Wave Length Inverted VEE w/ Apex angle 90º
Resonance Freq. (MHz)
Rs (ohms)
Xs (ohms)
SWR
Zo / SWR (ohms)
Z measured (ohms)
Z calculated (ohms)
14.380
27
9
1.9
26
26
28.46
¼ Wave Length – 50” With Center Load Coil and Mag Mount on Car Roof
20m Mobile w/ Common Mode Choke
Resonance Freq. (MHz)
Rs (ohms)
Xs (ohms)
SWR
Zo / SWR (ohms)
Z measured (ohms)
Z calculated (ohms)
14.148
41
20
1.6
31.25
45
45.617
Note: High Xs reactance leads to poor impedance estimation via the simple impedance check.
½ Wave Roll-up J 300 ohm Twin Lead – 72” coax length
