[TowerTalk] Inverted L for 160 Meters

[Tim Duffy K3LR]

Hello Chet!

The radials are laid on the ground. They self bury after a few months.

I was amazed how well this simple antenna worked. The efficiency is really
helped with the full size 1/4 wavelength radiator. 

My NEC model comparison indicates that the gain is only 5.1 dB less than a
fully vertical 1/4 wavelength element with 60 1/4 wavelength ground mounted
radials!

CU on 160!

73!
Tim K3LR 

-----Original Message-----
From: Chet Moore [mailto:ChetMoore at cox.net] 
Sent: Sunday, October 14, 2007 10:51 PM
To: k3lr at k3lr.com
Subject: Re: [TowerTalk] Inverted L for 160 Meters

Tim,

I put this e-mail in my hints and kinks file.  The two radials.......were 
they laying on the ground or elevated ?  from the sound of the space 
available,
it sound like they were probably laying on the ground.   This article by 
itself should lead to a large number of 160 enthusiasts who thought they 
could not get a 160 antenna on their lot to give this a try.

Thanks for sharing

73

Chet N4FX


----- Original Message ----- 
From: "Tim Duffy K3LR" <k3lr at k3lr.com>
To: "'Tom Crothers'" <TCrothers at columbus.rr.com>; <towertalk at contesting.com>
Sent: Sunday, October 14, 2007 11:15 PM
Subject: Re: [TowerTalk] Inverted L for 160 Meters


> Hello Tom:
>
> Here is an easy antenna that I built last winter for 160 meters. It is
> simple to build and works very well. I posted this to the TopBand 
> reflector
> last December and many operators built this and say it works great.
>
> December 2006:
> For the ARRL 160 contest a few weekends ago, I needed a quick and easy way
> to get on TopBand from my Oklahoma QTH.
>
> I am in a very antenna restricted area and my back yard is only 50 ft 
> deep.
>
> I purchased 450 ft of #16 insulated THHN  wire (about $45.00). I cut three
> 132ft lengths. I soldered one length on to the center of a SO239 chassis
> mount (UHF female) connector. The other end of this wire I curled around 
> for
> a string. The other two 132 ft pcs I soldered to the SO-239's outside 
> (using
> 2 holes) points
> for radials.
>
> With a fishing pole I casted up over the back yard tree that stands about 
> 50
> ft tall. I proceeded to pull the curled end with string over the tree. I
> pulled the first 20 feet of the antenna (coming from the SO239) vertical
> with another string to the chimney of the house. The two radials were 
> pulled
> out away from the feed point. The antenna went on top of the tree and down
> the other side forming a upside-down "U".
>
> I hooked about 40 feet of RG8X to the feedpoint (also a 4 ft ground rod)
> coiling about 20 ft in a 1 ft diameter bunch to form a current choke at 
> the
> base.
>
> Inside I hooked up the Icom IC765 and the VSWR was 1.1:1 at 1830 without
> trimming.
>
> The antenna worked great! With a part-time 100 watt effort I worked 46
> states and 7 DXCC countries. Not bad for a simple 160 meter antenna.
>
> 73!
> Tim K3LR
>
> http://www.k3lr.com
>
>
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Tom Crothers
> Sent: Sunday, October 14, 2007 10:02 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Inverted L for 160 Meters
>
> Hello all,
>
>
>
> There's an article in the October 2007 QST by Steve Ford entitled "Waiting
> for the Sun".  For those of you who read the article, and may have some
> information/answers, I have a few questions regarding the construction of
> the 160 meter inverted L antenna that is shown in Figure 3 of the article:
>
>
>
>
>
> *        Do I understand correctly, that C1 in the diagram is a simple
> variable capacitor that ranges from 100 pF to 800 pF?  (I found one, and
> purchased it)
>
> *        Is it for tuning the antenna for minimal SWR?
>
> *        How did the author arrive at the wire length of 165 to 175 feet?
>
>
>
> I know these are pretty basic issues/questions, but I built this antenna
> today.  I want to be sure I've built it correctly, and moreover, I want to
> be sure I understand how to tune it correctly.
>
>
>
> * Right now, I can get a minimal SWR of 3:1 at 1.810 MHz by tuning the
> variable capacitor for min SWR.
> * I don't have any radials installed at present.  The coax braid is
> grounded to my tower ground (three 8 ft rods bonded together)
> * I plan on adding some radials (laid on the ground) tomorrow.  Should
> they be of any particular length to perform optimally?
>
>
>
> I've emailed Steve Ford addressing the above, but I also wanted to see 
> what
> the folks at TT think.
>
>
>
> Thanks all.
>
>
>
> 73,
>
>
>
> Tom
>
> W8KF
>
>
>
>
>
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