|
Post by carlbeck on Apr 12, 2016 8:43:54 GMT -5
I wanted to check the characteristics of 300 and 450 Ohm Ladder Line I have. I had 155 inches of 450 Ohm and 179 inches of 300 Ohm. I hooked it up to my 4170D and used the faction: "Distance to Fault". I followed the direction to measure the line and came up with the following:
The 450 Ohm line displayed: Zo = 314.003 ohms, and a velocity factor of 0.815. The 300 Ohm line displayed: Zo = 223.506 ohms, and a velocity factor of 0.840.
My question is: Why is this so far off from the designated 300 and 450 ohms specified for the lines used?
|
|
|
Post by Bob on Apr 16, 2016 17:48:59 GMT -5
A 1:1 balun will help. This converts the unbalanced output of the AIM to a balanced output. This should be good over the frequency range you are interested in. Something like FT50-43 is a good start. If you have other ferrite materials, try them too. Put the cal loads at the output of the balun to cancel it's imperfections.
After making the cal file, check the results when scanning with resistive loads.
--73/Bob
|
|
|
Post by carlbeck on Apr 17, 2016 7:25:28 GMT -5
Thanks Bob. I guess I should have thought of that.
Carl
|
|