GU4YOX - Antennas
The following antennas are currently being used at GU4YOX:
10,15 and 20 M - Triband Beam TB3 at 40-65' high
|
|
|
|
|
|
|
|
|
|
The 3 element tri-bander at full height at GU4YOX. The 160M vertical runs up adjacent to the tower. |
|
|
|
|
|
40/30M Either vertical ants (two element phased array) or single vertical
|
|
|
|
Array switching box detail |
|
|
|
40M element base detail |
|
|
|
The 2 element array with daughters trampoline in background! |
|
|
The 40M array is a two element cardioid array which I had heard about in several
journals but it was Chris G3SJJ that finally inspired me to build the two
elements. In the end I didn't fit an L-Match in the switching box but configured
it to also radiate broadside by feeding both elements in phase using some
Jennings relays I found for sale on the web. Utilising the 71 degree phasing delay
line gives about 3dB gain in either direction. The nulling of EU signals is also
of significant benefit for working US DX.
80M Inverted L at 40-65'
160M Inverted L at 40-86' high with 4500' of ground radials
|
|
|
|
|
|
|
|
160M Verical Antenna with beam removed and tower arrangement |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Inverted L Antenna wire alongside the 86' vertical tower section used in contests |
|
|
|
|
|
|
Tower Construction
With the weather in Guernsey tending to be rather on the windy side at times,
I decided to ensure that the GU4YOX tower was mounted very securely indeed. I
excavated a hole nearly 4 feet deep and 3 feet square and filled the hole with
C25 grade concrete which was also agitated such that it left no voids and was
packed into the hole well. The tower base assembly was temporarily built up
using high tensile bolts nearly 15 inches long and then half inch reinforcing
bar was formed into a cage and the entire cage/bolting assembly was welded in
situ to form a very strong sub-structure once in place. The tower base assembly
was positioned and levelled in place above the hole before the concrete pouring
exercise was undertaken. Here are some photos of the tower construction
unfolding:
|
|
|
|
|
|
|
|
|
|
Tower base assembly welded and ready for positioning in prepared hole |
|
|
|
|
|
|
|
|
|
|
|
|
I had to protect a water pipe by over lining it with pvc before the pour. This is the hole completed! |
|
|
|
|
|
|
|
|
|
|
|
|
Levelled and aligned. The structure was ready for concrete |
|
|
|
|
|
|
|
|
|
|
|
|
|
The completed tower base with a radial copper bus ring built around the edge of the tower. Slowly I added over 4500 feet of radials to the base for the 160M antenna |
|
|
|
|
|
|
|
Low Band Receiving Antennas:
2 short Beverages West and South
160M Receiving Loop 6' diameter
Home
