At 18:21 8/13/98 , Ed Koch wrote:
> anybody use an different measurements on a hygain 2ele 40m beam than
the manual
>calls for? i have set mine for low cw and at 7.05 i have a 1.6swr. at
7.000 i have a 2.9 and at 7.1 ihave a >2.0. all is set by original
specs. antenna is mounted at 85 ft.
=============================================
Ed,
I went up and down the tower for this antenna many times back when I
was younger, and came up with quite a few modifications to this antenna
for the original 2 element design and as a 3 element array.
I documented the work I did, and still have the data all in a nice
folder, but have just never gotten around to re-typing the info into
the computer. I still owe this data to others that have requested same
of me. Now that I am prompted, I think I will try to get it into the
keyboard over the course of next week.
HERE IS A LITTLE KNOWN FACT....................
There are two (2) sets of "assembly and design dimensions" for this
antenna.
A set of dimensions from a 1976 assembly manual has different values
than a later 1984 assembly manual.
Use the later dimensions, which make for a longer set of elements for
the antenna.
Also, if you can lengthen the boom out to 18 1/2 to 20 feet, the
antenna will have a lower Q for bandwidth improvement.
For an almost flat SWR at 7.10, the element lengths I used were.
42' -2 1/8" for Driven Element
47'-3 1/2" for the Reflector
These dimensions allowed me to go to low SSB and CW with an acceptable
SWR.
In making the antenna into a 3 element array, I used 37'-2 1/8" for the
Director.
The Reflector to Driven Element spacing I used was 18'-6"
The Driven Element to Director spacing I used was 20'-11"
The antenna is now up at my shack as a 3 element array, using Mosley V
blocks as element supports, getting away from the Hy-Gain clam shell
type holders.
Unfortunately, I failed to take into consideration the fact that the
black insulators and clam shell holders act as capacitors, and function
as a part of the tuned circuit of each element. That is another story
completely.
73,
N5RP
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