If you are registering, please use your callsign as your username. If you don't have a callsign yet, use your firstname and the Initial from your last name, like John M

SWR Indicator for balanced line

Questions and solutions about your antenna and feedline projects.
VE3PCP
Posts: 90
Joined: Tue Jun 27, 2017 1:10 pm
x 8
x 11

SWR Indicator for balanced line

Hi:
Many years ago I made one of these and it worked very well as a basic indicator of SWR on 300 ohm twin lead which I have used for many antennas over the years.
I just taped it to my feed line right after the tuner so I could see it from my seated position while operating.
Not sure how many of you use balanced line but here is a link to the article about how it works and how to build one.
Enjoy!
Rob
VE3PCP
http://www.rfcafe.com/references/qst/tw ... r-1947.htm
You do not have the required permissions to view the files attached to this post.
0 x

VE3PCP
Posts: 90
Joined: Tue Jun 27, 2017 1:10 pm
x 8
x 11

Re: SWR Indicator for balanced line

I rebuilt my unit yesterday and did up a short video to explain it and show it in operation.
Enjoy!

[BBvideo=560,315]https://youtu.be/TBWElwXIBXU[/BBvideo]
0 x

va3ts
Posts: 101
Joined: Tue May 16, 2017 11:24 pm
Location: Shallow Lake, On
x 13
x 6
Contact:

Re: SWR Indicator for balanced line

Some history and theory on open wire feeder and swr

[BBvideo=560,315]https://youtu.be/w1eE13UXAKs[/BBvideo]

open line - spacing usually < 1% of the wavelength

When the line length is an even multiple of wavelength/2 , the input resistance is equal to the load resistance, regarless of line Zo.

The characteristic impedance of air insulated parallel conductor line
Zo=276 log 2s/d where s = center to center distance d = outer diameter of conductor
0 x
GBARC Forum Admin ... send questions etc to contact@gbarc.ca