[SADXA] Output Impedance of Baluns

[W7EXG (Bill)]

These comments were made by Bill Davis W7EXG at the 12-20-18 SADXA meeting.


OUTPUT impedance of Baluns is not alike.  

For example, the output impedance of a 1:1 Balun [from Balun Design], is
Inductive with input terminated on 50 or 75 ohms. 

The output impedance of a 1.5:1 balun (75/50 ohm Balun) (from Balun Design)
is capacitive with input terminated on 50 ohms.  

Thus, for a fixed rotatable dipole element length, the resonant frequency of
the dipole using a 1:1 Balun (75 ohm Coax) will be substantially different
than for this same dipole element length with the 75/50 ohm balun (50 ohm
Coax).  

BOTTOM LINE: Output impedance of Baluns is important, yet this important
characteristic is typically not specified.

73's
Bill W7EXG