If you follow this link http://k6mhe.com/n7ws/Ladder_Line.pdf to my paper and
look at Table 1, it gives the measured values of four different Wireman P/Ns.
Note that these are 50 MHz values and transmission line Zo and Vp are anything
but constant at lower frequencies. Likewise, these particular lines use
copper-clad steel conductors that "misbehave" at lower frequencies so Eq 4
somewhat falls apart when the conductors do not have a well-developed skin
effect. I mentioned this in the paper but did not account for it in the equation.
Wes N7WS
On 2/5/2017 5:11 PM, Hardy Landskov wrote:
Hi Jim and all,
The email below reminds me of a problem I had some years ago with "450 ohm
window line". Nothing seemed to work. I then found an article that explained
how to measure the Zo of coax/ladder line. I measured a piece of window line
and it was 374 ohms! I found out in the archives that W8JI had measured 377
ohms with a piece of window line. We exchanged emails and he was elated that
I had verified his results.
Here you have two different sets of equipments, two different runs of ladder
line, and different times. I was very happy myself. I have an HP8753B so it
was no problem to run through the numbers. It was a very eye opening
exercise!!
Bottom line: Use 375 ohms for matching tuners and other things when using
this line.
73 Hardy N7RT/4
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|