On Sun, 16 Apr 2006 21:55:45 -0400, Buck wrote:

I'm using a random length loop, probably about 200 feet fed with
450 ohm ladder line. The ladder line hangs about 18 inches from
my tower and I get good reports from all over. My advice, if you
have and idea, try it, if it works great. If not, back to the drawing
board

Jim WU7G


In general there is a magnetic/electric field between the conductors in
twinlead feed line.
Dave WD9BDZ

Dave,

Just to clarify, is the 'magnetic/electric field' to which you refer
the same as saying 'electromagnetic field'? I am just trying to
clarify whether it is just how you expressed it or if you are making a
distinctive difference.

Thanks
Buck

I agree, however in my current situation I really can't keep going up and down to the roof because I'm renting a suite in the basement and I'm already pushing things with all the feedlines and isopole VHF antennas already up there. The landlord is a really decent guy and has been totally reasonable --- so far. If I keep wanting to do more and more he's going to feel obligated to say no sooner or later.

There's another issue, though, a more important one --- I moved the feedpoint to the SW corner of the roof (pic at http://members.shaw.ca/cyberhun/ham.htm) and used coax for the feedline. But when I was up there, I was so freaked out by the height that I forgot to waterproof the termination --- but I'm not going back up there til I can figure a way to do it more securely. It doesn't matter how many guys are holding the bottom of the ladder. If it starts to slide one way or the other, there's too much leverage for anyone to stop it. Water damage be damned, a fall from that height could be deadly.

A much simpler antenna is possible at your QTH, based on iteration #4.

Feed your 110 feet long antenna in the center with 600 ohms open wire
tuned feeders [or 450 ohm ladder line ... however, 450 ohm line is more
lossy in bad weather]. You can twist the ladder line at 1 turn every two
feet, or the open wire line 1 turn in 4 feet, to accommodate any
imbalances cause by nearby objects.

If your MFJ 949E does not have a balanced output then use a short
section of coax, 2 to 3 feet is PLENTY, to connect between the MFJ949E
and a MFJ 912 Balun, and then to the tuned feeders.

This is a very low loss setup that should work the following bands with
good to very good antenna efficiency: 80/75, 60, 40, 30, 20, 17, 15, 12
and 10 meters. [My setup, very similar, has a maximum of 1.4 dB loss
across this set of bands using 150 feet of feedline ... 1/4 of an S unit.]

NOTE: The G5RV is in reality a single band antenna!! It is designed for
20 meters where it performs admirably! It can be tuned to work other
bands. However the losses in the coax section can become moderately
high. The CF Doublet with tuned feeders has much lower feedline losses.

Thomas anonymous wrote:
I agree, however in my current situation I really can't keep going up
and down to the roof because I'm renting a suite in the basement and
I'm already pushing things with all the feedlines and isopole VHF
antennas already up there. The landlord is a really decent guy and has
been totally reasonable --- so far. If I keep wanting to do more and
more he's going to feel obligated to say no sooner or later.

There's another issue, though, a more important one --- I moved the
feedpoint to the SW corner of the roof (pic at
http://members.shaw.ca/cyberhun/ham.htm) and used coax for the
feedline. But when I was up there, I was so freaked out by the height
that I forgot to waterproof the termination --- but I'm not going back
up there til I can figure a way to do it more securely. It doesn't
matter how many guys are holding the bottom of the ladder. If it
starts to slide one way or the other, there's too much leverage for
anyone to stop it. Water damage be damned, a fall from that height
could be deadly.