[TenTec] What makes the 238 good or any other tuner good?

[Robert & Linda McGraw K4TAX]

Based on average antenna heights above ground for the average ham location, 
for a 1/2 wave antenna operated on an even harmonic, the feed Z is typically 
in the order of 1000 to 1500 ohms.  In theory, in free space, yes it is much 
higher.  In practice, it isn't as high as one would imagine.  With 50 ohm 
coax the line SWR is ~30:1 while with some value of open wire line it is 
~3.3:1.

73
Bob, K4TAX