Topband: Inverted L off tower?

[Bob Lawson N6RW]

Jim

I put up a 70 foot tower (Tashjian DX-70) with a SteppIR DB-36 Yagi 
about 5 feet above it last year.  I hung an IAC "Double Bazooka" 
Inverted L on it with 3 to 4 foot yardarm at the top of the tower.  The 
tower is on the highest peak of my property and none of the pine trees 
are high enough to run the "horizontal" part of the L horizontally, so 
it slopes around 45 degrees.  I also run my Yagi coax and control lines 
down an 18 inch yardarm that is 120 degrees away from the Inv. L in the 
horizontal plane. Some of the radials are 135 feet long, but most of 
them are 70 feet.  The IAC "Double Bazooka" design is quite broadband 
(less than 2:1 from 1.8 to 2.0 MHz) - similar to a cage design.  It's 
SWR is lowest when I set the SteppIR DB-36 to the low end of 80 meters.

The antenna gets out pretty well.  I get good reports from Europe from 
here in Arizona (even from guys I can't hear).  I was able to work 74 
countries in my first year on 160 with this antenna - including some of 
the major DXpeditions we had this year.  I hope to have a Hi-Z 4-square 
RX antenna up in time for next season, so I'll be able to hear more 
people that can hear me, but I currently have no plans to change the TX 
antenna.

73 de Bob N6RW


On 5/23/2016 7:34 AM, Jim Miller wrote:
> Thanks for all the feedback and suggestions. My friend (not me...) is
> considering his options.
>
> 73
>
> jim ab3cv
>
> On Mon, May 16, 2016 at 7:40 PM, Jim Miller <jim at jtmiller.com> wrote:
>
>> One of my friends is thinking about installing a 70 ft. tower with a
>> 2-element shortened 40M yagi. He is thinking about installing the new tower
>> in a location where he now has a vertical used for 80M and 160M (i.e - the
>> existing radials will terminate at or close to the base of the new tower).
>> He is planning to relocate the 80M vertical to another location with other
>> radials. He would like to support an inverted L for 160M off of the new
>> tower, using the existing radials. His question is, how far must the
>> vertical leg of the inverted L be spaced from the new tower, with a view to
>> keeping it close enough to use the existing radials?
>>
>>
>> Thanks
>>
>> jim ab3cv
>>
>>
>>
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