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SW aerial - Printable Version

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SW aerial - fields 100 - 03-11-2014

Hope I am posting in the right forum. What is the economical way to get adequate reception on SW? At this point I am just using 15ft of wire on the first floor of my place.Mediocre reception.Should I run the wire up to the roof, and if so, how far above the roof line? Should that insulated wire be shielded if the portion of it will be touching or laying inside the aluminum gutter? Thanks.

RE: SW aerial - morzh - 03-11-2014

With most of my radios a 6-8 foot wire provides me plenty of SW.

RE: SW aerial - Art Hoch - 03-11-2014

My sw wire runs up the slope of my roof to the peak...about 12 inches above the shingles...about 20-25 feet long. Very adequate. Standoffs keep it away from the guttering until it connects with insulated wire going into the house.

RE: SW aerial - captainslack - 03-12-2014

That length of wire ought to be fine. It'll receive better if you can get it outdoors.

RE: SW aerial - Eric T - 03-12-2014

I have about 30 feet of wire going up into my attic space. I can pick up Radio Romania, China Radio International, A multitude of South American stations, and WWV from Ft. Collins, CO down here in FL.

RE: SW aerial - Radioroslyn - 03-13-2014

General rule of thumb is as high up as you can get it, Used a slingshot to get in up into the trees here. The longer the better it will work on lower frequencies. The ant I use most is about 120' long and up 35' or so. All I got is midget trees around.
A good ant for SW would be 60' of wire cut in the center and fed with 300 ohm twinlead. Up as high as you can get it, away from power lines and other noisy stuff.
GL
Terry

RE: SW aerial - fields 100 - 03-13-2014

@ Radioroslyn,

60 feet sounds good to me.Can be done. Please explain what does it mean "cut in the center and fed with 300 ohm twinlead"? Do you mean connecting 2 30 footers with a 300 ohm resistor at the top, then splice the wires together at the set? Thanks.

RE: SW aerial - David - 03-13-2014

Hi, use two different system for shortwave first is a single long wire about 25 feet located alone the roof of a shed. The second ant would be a dipole connected to 300 ohm lead each half about 15 feet. Ant height about 20 feet. Would like to go higher but to many thunder storms in Florida. Look around the net for owners manual for a Hallicrafters S-38,a,b,c,d,e or SX130,SX133 will show how to set up a dipole ant. Try nostaligaair. David

RE: SW aerial - Radioroslyn - 03-13-2014

Ok what you do is take two sections of ant wire 30' and connect one end of each of these to the twinlead. Twinlead is that flat ant wire that you use to use to connect the TV ant up with before all this coax stuff come out. I use a small section of pvc pipe to hole the wires in place. Same with the ends use rope thru holes drill into the pvc to support the end in the trees. The other end of the twinlead goes to the radio.
Terry

RE: SW aerial - fields 100 - 03-13-2014

Thanks, guys.

RE: SW aerial - fields 100 - 09-03-2014

Finally, I am building SW antenna, but having difficulty locating the twin lead cable. Can I substitute it with 75 ohm coax?

RE: SW aerial - morzh - 09-03-2014

Fields,

I am not sure but...for SW antenna, why do you need a normalized impedance feeder line?

RE: SW aerial - fields 100 - 09-03-2014

That is what I have been advised on this thread: feeder should be twin lead 300ohms. I'd be happy to do it easier way if so possible.

RE: SW aerial - morzh - 09-03-2014

So you are using a loop type or twin rod vibrator? Not one wire and GND type?

RE: SW aerial - Mondial - 09-03-2014

Fields, if you are using a radio with the standard "A" and "G" antenna connections, the 75 ohm coax will work fine. Connect the center conductor to the "A" terminal and the shield to the "G". At the other end of the coax, connect one antenna wire to the inner conductor and the other to the shield.

In this instance you are not matching impedance but more using the coax as a shielded cable to minimize local interference pickup. Try to keep the coax length as short as possible.