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Channel Jumper · August 17th 11, 10:30 PM

Quote:

Originally Posted by DrYattz

My 15 year old son is exploring shortwave radio, and has purchased a
Realistic DX-394a. We're experimenting with various antenna
configurations, now trying an inverted L. The layout so far can be
seen at:

http://i258.photobucket.com/albums/h...t/antenna2.jpg

So, a single strand wire crosses the yard at a height of about 14-18
feet, stretched east-west, insulated at each end, and another length
of wire connected to it drops to below a window, then passes through
the wall and to the Hi-Z antenna input. (The diagram shows a
lightning arrestor, but that isn't attached yet.)

But it seems to offer little or no advantage over the little
telescoping antenna. In fact, the best reception is when we touch the
antenna lead wire to the telescoping antenna. Do you suggest:

Buy a good verticle antenna.

1) an antenna tuner? Antenna tuners only adjusts the resistance of the line, the line resistance is important if you are transmitting, but not really all that important when you are in the receive mode.

2) coaxial cable running from the radio (Lo-Z input) to the end of the
75 foot run?
Coaxial cable - has more loss at higher frequencies then lower frequencies.
Some antenna tuners has the capability of converting ladder line - 450 ohm to the appropriate load necessary for your receiver.

You need to build or buy a antenna for the frequency you wish to receive.
You also need to build or buy a antenna rotor - if you wish to receive in more then one direction.

3) a north-south run?
If you point your antenna north - you can use short path propagation to recieive signals out of Europe.

Basically what Short Path Propogation is - is a way to circumnavagate the earth by using the shortest route.
If you take a piece of string and measure from England ( UK ) to Long Island NY - you could get two completely different measurements by just putting the string across the globe as opposed to looping it around the upper portion of the globe and back down to the destination. The long path is the direct route - west to east.

The short path would be up towards Nova Scotia and back down towards
All the great navagators - including Chris Columbus understood how to get from point A to point B in the shortest amount of time.

That is also probably the reason why the Pilgrims landed on Plymouth Rock - because they ran out of BEER and needed to stop and brew a couple of kegs before they could continue south to Virginia to set up their new colony. - It was because New England was right along the way to Virginia by short path navigation.

4) a completely different configuration?

5) anything else?

Rees Chapman
winwinsit at gmail period com

Go back to what I wrote about what I said about your receiver.

A good receiver will receive in all directions with the used of a dipole antenna such as a G5RV - long.
The key is to get it up as high as you can get it in the middle and ends.

The book says to put it 1/2 a wavelength or higher for the frequency you desire to receive.
That is pretty easy for 10 meters - because the 10 meter band is only like 36 feet long.

160 meters would be almost impossible.
The FCC and the FAA limits tower height to 200 feet - for a licensed amateur, even at that, they might require you to use blinking strobe lights and there is rules - if you are in a flight path or closer then 5000 yards from a public use airport.

It all goes back to what I wrote the first time, get yourself the ARRL handbook for the TEchnician Class License and the ARRL Antenna handbook and start reading and attend some club meetings at the local ham club in your area and see what you can learn from the more experienced hams in your area.