[TowerTalk] 6M Transmission Line

[Jim Brown]

On 7/19/2013 7:59 AM, Hector Garcia XE2K wrote:
> There is no problem to run the LMR-600 ,  if you are sure you have the 75 ohms version  you can "adjust" for 50 ohms

There is a simple, but tried and true method for using 75 ohm cable to 
feed a 50 ohm load.  Simply make the 75 ohm line an EXACT multiple of 
half-wavelengths at the operating frequency. This works because the 
impedance transformation that happens in any transmission line comes 
back to where it started every half-wavelength.

Getting the length right is also easy -- put a connector on one end and 
measure the impedance using any antenna analyzer with the far end 
shorted. When it's an exact multiple, it will measure as a short.  To 
calculate the length, use the velocity factor of the coax and cut it a 
little long, then trim until it's right.

73, Jim K9YC