Ham Radio Forum

Most of you probably know that the Salt Lake City Delta Loop receiving antenna fell earlier this year when a supporting branch on a tall tree broke during an unusually strong wind storm. It has been temporarily installed much lower as a sloping loop since that time. I originally planned to re-install it essentially as it had been before when weather permitted. Recently I decided to install it much differently, so it will be able to function as several different types of antennas by means of remote switching via Cat5 Ethernet cables that run along with dual coax feed-lines to a new feed point.

A wideband toroid transformer matches the 50-ohm unbalanced receiver input impedance to 150-ohm balanced coax feed-line made from two 75-ohm RG-6 quad-shielded lines. A remotely tunable matching network at the antenna feed-point matches the antenna impedance to the 150-ohm balanced-line impedance and also balances the feed-line currents, so the feed-line current and voltage distributions down the lines are always flat and the line currents from line-to-line are opposite, but equal in magnitude.

I won

After unsuccessful attempts last week due to wind, today we managed to get lines over the top of two 80-foot high trees (natural antenna masts) that are slightly more than 200 feet apart. Two 20-lb test monofilament fish lines were tied to a cluster of two 36-inch helium-filled balloons. With one person each side of a tree it was easy to position the balloons over selected high branches during a calm period this afternoon when the wind wasn't blowing. Once the lines were correctly position it was only necessary to pull them down over the branches.

The monofilament lines will be used to pull a succession of heavier lines and eventually a 3/32 inch plastic coated, zinc coated, 7x7 strand steel cable. The steel cable will have a pulley at the top through which Dacron line will pass to support the ends of the antenna. Plastic coated steel cable will be used, because years of experience with tree supported antennas have taught that lower tree branches blowing in the wind eventually fray and wear through Dacron line.

One problem with being up high is that the wind usually blows. It is blowing again tonight. I am hoping it doesn

Fortunately, the wind didn

Unusually high winds tonight have been trying to blow-down the new antenna supporting lines we just installed over trees, but so far the lines are still in place. They will be much less apt to slip after the antenna is hoisted, because antenna wire tension will tend to hold them in place. Right now they are a little vulnerable.

Lightning caused two power outages earlier tonight, so the website servers and the Salt Lake City receiver were running on emergency power for a while. The weather has calmed-down a bit now, so maybe the worst is over. I am hoping the weather will be good enough tomorrow to allow continuation of the various antenna projects.

-Bob

Sounds like perfect antenna construction weather
If the law holds true, the new antennas will get an extra 10db of mystery gain.

P.S. I finally got my tech license.

..
KE5FWS
Jesse

Jesse,

Congratulations on the new license.

Considering all the