View Single Post
  #6   Report Post  
Old October 25th 10, 05:50 PM posted to rec.radio.amateur.antenna
KD7HB KD7HB is offline
external usenet poster
 
First recorded activity by RadioBanter: May 2009
Posts: 21
Default 300 Ohm Ladder Line Issues

On Oct 24, 8:23*pm, Tom Horne wrote:
I have read that the presently available 300 ohm ladder line is
unsuitable to use at some amateur radio frequencies because of it's
construction and the losses caused by skin effect in the copper coated
steel construction. *I have been using a Terminated Folded Dipole in a
flat top configuration as my HF antenna at home. *Having recently
acquired an Icom AH-4 Antenna Coupler I am considering converting it
to a simple folded dipole, *feeding it with 300 ohm ladder line to
match it's nominal impedance from the coupler. *I know your sure that
there is a question in here someplace so is there better quality 300
ohm window line available that is entirely stranded copper in it's
construction?
--
Tom Horne, W3TDH


Tom, what length of feed line are considering? How do you intend to
install it and support it from your shack to the antenna?

I have tried both 300 ohm TV type twin lead and ladder line. Both are
quickly affected by rain and snow. But more importantly is the wind
whipping the feed line and breaking it somewhere. About once per 6
month period I had to pull the whole antenna down and either replace
the feed line or find the break and repair it.

If you are able to secure the feed line with insulators every 10 feet
or so, the wind damage should be minimal.

A couple of years ago I made my own 600 ohm open wire feed line and
the wind is no longer a problem. The wind resistance is very low and
weather is only a problem when ice collects on the feed line.

IF you are interested, the 600 ohm feed line is #14 copper with
plastic rod insulators every 10 feet. The length from shack to antenna
is about 125 feet. Two poles support the feed line on its way and the
shack end is attached to a rope and pulley so I can adjust the
tension, or let the end down for maintenance.

Just some thoughts for you. Good luck, and don't be afraid to try
different schemes.

Paul, KD7HB
Central Oregon desert