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The W7LPN version of the Inverted L Multi-Band 10-80m Antenna

(See latest update 03-30-09)

Electric Fence Wire- I prefer electric fence wire for all my latest antenna experiments. It has worked well for QPR camping, outings, and emergency preparedness, as well as fixed base antennas. I keep a 50 meter roll on a bolt with a rechargeable drill to retrieve the antenna wire, and a cheap fishing pole, 10lb line with 1oz sinkers, in my camping bag. This is all I've ever needed to throw a long wire up in the trees. In this inverted L, limited space was what was driving me, so I used every inch of wire I could fit.

I'm using an
ICOM 730 & LDG Z-100 auto-tuner, so I didn't get too concerned about measuring. I just got it up as high as I could, at as steep and angle as possible
& hoped for the best. The results were satisfying.

It is important to use
battery grease or similar compound when connecting copper to aluminum or grounding the feed point. I used spray electric tape over all exposed
connections.

My home has a complete metal outer shell, a new metal roof,
and aluminum siding which is buried at the base about 5-6 on average. I
believe I'm well grounded.

The total length of the antenna is about 100 ft. 70 feet to the bend, then about 30' down at an angle to the pole extension. These dimensions were used to add the maximum length of wire and stay within my property lines. With the 70Ft straight wire alone, I could get 80m, but not 40. I shortened cautiously, then I got 40m, but lost 80m. When I added the vertical section, I got 80-10m and my little autotuner will tune it all at full band widths. 

So far this is a very quiet antenna and I'm receiving better reports than the carolina windom I had previously. It is very well grounded!  Net controls on 40 & 80m tell me it's the best signal I've had yet & with a small lot, that's important to me.
 

4:1 Guanella Balun- http://www.n0ss.net/qrp_4-1_guanella-type_balun.pdf This balun was simple to build and works as written. I ran Heliax from my rig to the feed point, which is at the left of the picture, above my metal roof about 5 feet mounted on a used golf course flag pole. One end is run a short distance to the metal roof, the other end extends the full length of my home & shed to a 35 ft mast with a 5 ft fiberglass extension, then drops about 30 ft to about 7 ft off the ground mounted to a horizontal PVC extension from the shed keeping the wire away from the metal building. I have a pulley at the tip of the pole, polynylon rope, an insulator and can easily lower the antenna when needed or stormy weather. With the wire laying on a metal roof, lighting strikes are of minor concern.
Any questions or suggestions please email
rick at my callsign @cableone.net.

Latest Update 03-30-09

After much on the air testing

It performed marginally on 75M and not very impressive on the higher bands, so I removed the balun at the feed point, threaded an SO-239 into my metal roof and feed it directly to the wire from there, leaving the flag pole in place to give elevation off the roof for a few feet.

The metal roof can now act more like a ground plane. I ran the transmitter to a manual home-brew roller inductor tuner, and the bi-pass switch goes thru the auto tuner. It auto tunes nicely on the higher bands with improved performance. I bi-passed the auto-tuner and use the manual for 75m with improved performance. If the connection at the SO-239 holds up it should work well for some time.






 



  

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