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I am presently running an Elecraft K3 with a beam for 6-20m.   For 10-160m,  an inverted "L"antenna is used.  This antenna is suspended 40 feet above a 20 x 40 foot metal shed. The wire is fed a auto tuner that is mounted and grounded to the shedThe metal shed makes a great ground, the only downside is that the shed is 300 feet from the shack, making for about 3dB of coax loss on 10 meters.

12/12. Built a 3 element 17m Yagi and hung it from a line suspended between two trees.  It is steered by a anchor line running from one end of the boom to a sawhorse on the the ground. I love the front to back ratio of this antenna, but running outside to change the heading is getting old. Field strength measurements were made by parking a mobile receiver a mile away and recording the S meter while rotating the antenna. The receiver was then connected to a calibrated signal generator to determine the power required for a given S meter reading. The front to back ratio measured 21 dB, about 4 dBmore than the calculated 17 dB. Perhaps this is due to reading the signal at ground level rather than at the elevation angle of maximum gain.

The 17 meter 50 Ohm Yagi dimensions:

Reflector334 inches

Director300 inches

Driven318 inches

Reflector to driven spacing 84 inches

Director to driven spacing 65.75

Swr < 1.4:1without matching network. Note that this Yagi was optimized for best SWR. No matching network is used. Measured from the center of the boom,the first 60 inches of each element is 0.875 dia., and the remaining lengths are 0.663 dia.

11/13.   Installed a 55 foot crank-up, tilt-over tower with a Steppir 3el mounted on a tilt plate so all antenna work can be done at ground level.  On the air testing showed that the Steppir has about a half S unit more gain than the hombrew 17m Yagi.

6/14  Rope holding 17M Yagi parted converting the antenna into copper and plastic scrap.  The rope,  from one of the big-box stores, was not UV resistant.

9/14  Experimental 40M loaded dipole with matching network. 

 

This antenna seems to work very well on local and transatlantic DX while only sitting 6 feet above the ground.   The PVC is 1.5 inch,  coils ( 16uHy) are 27 turns of #12 close wound. Tuning is done by sliding a shorted turn in the coils.  A C-L-C PI network is used to match the 10 ohm feedpoint resistance of the antenna to the 50 ohm coax. Tx capacitance is 1880pF,  L is 0.363 uHy,  and antenna side capacitance is 3600 pF.   The antenna elements are 102" CB whips.  Bandwidth is around 30 KHz at the 1.5:1 SWR points and 1:1 at the center frequency.   

 

 

 

2/15   40M double "L" wire beam

Now working on a two element vertical beam for 40 meters using a passive reflector. The  antenna resembles two L's (LL),  with the lower elements 7 feet above ground.  Vertical elements are suspended from a line between two trees.  Initial tests involving a qso with a mobile indicate 6-10 dB gain over the shed antenna and a beamwidth of about 90 degrees. 

1699626 Last modified: 2015-02-15 17:02:52, 3366 bytes

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