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| The A3S at the place where now the LP7 rotates | The D3W as vertical dipole on the wooden mast |
I have small directional antennas on the roof of my house since 10 years. First a HB9CV for 10m which was set up from the no more required TV antenna material (22mm aluminum square hollow profile) in the spring of 1991. This antenna played very well, I succeeded to work my last, then still missing DXCC entities - XQ0X and VP8SSI. As the conditions became worse on 10m, the antenna emerged from a 10m antenna to one for 15m. However, the desire came up for more and so emerged a small 2 element homemade triband beam of Diemo - DL4LQM. It was then complemented by the WARC rotary dipole D3W by Cushcraft on the same mast. The mutual influences kept in boundaries, although both antennas were mounted only in an approximate distance of 50cm of each other.
In 1997, I however have increased to 3 elements and built a A3S in lieu of the 2 ele antenna. However there arose problems then in form of an influence between the D3W and the A3S, because both radiators were situated even more densely together. A way out above was not possible and so I did not succeed to achieve half-way bearable resonances on the bands. Whether I liked it or not, I had to remove the WARC antenna from the mast on the roof and have finally mounted it as a vertical dipole on my wood mast. This made a bit of a hard job of it on the WARC bands, but on 17 and 12m wishes were however left open.
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| The A3S at the place where now the LP7 rotates | The D3W as vertical dipole on the wooden mast |
In the
last years I have however thought again and again about it, how
the bands from 20 to 10m could be covered completely with one
directional antenna. It stood however in the foreground that no
larger load momentums could be induced into the roof timbering
and that the assembling possibility on the walking board of the
roof had to be taken into consideration as well. With these
guidelines in mind the choice was taken for the LP7 by TITANEX. Weight and wind load differed only
slightly from the A3S. The problem consisted only therein, how to
assemble it on the roof. After a brain storming with Tom - DL5LYM, who had already gathered abundant
experiences with the LP5, we realized that an installation must
be possible on the narrow gangway of the roof.
And so lay the LP7 then in form of a 6m long cardboard tube on
the court of my house on a beautiful day in March 2001 and had to
be brought onto the roof yet!
The March and also still the April presented bad weather. The
spring was a long time in coming this time. About an installation
was not to be thought. The time was used to assemble the
individual elements. After that followed a sample installation on
ground level. Corresponding marks were placed on the boom where
the individual elements were fastened. Everything fitted and the
mounting technology well thought-out that it could go off at
suitable weather.
On April 25, 2001 we've finally made it. After dismantling the A3S,
the assembled elements and the boom were lifted at the western
gable and taken off on the roof. After that the boom was screwed
on the mast and the individual elements fastened one after the
other on the boom. Everything worked as I have had it in my mind
and the installation preceded drafty. However, the most difficult
part was yet to come - the installation the auxiliary boom with
the placing of the clamps and the cable connections to the
even-numbered
elements.
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| The first elements are mounted at the boom... | |
Thereby it showed that the included clamps are unsuitable for the installation under these conditions. One needed then three hands, because not only the clamps have to be placed, but simultaneously the cable connectors had to be placed below and everything had to be pressed together with the grip. And this all freely standing on the narrow walking board. Despite safety belt and rope apparently impossible.
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| DL3XM working freely standing |
I have
therefore used regular hose clamps in the kind like they are used
at Cushcraft or also in the car industry (stainless steel version).
There were no problems in putting on and tightening of the clamps -
details see here.
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| All elements are mounted on the boom now | |
After all elements were joined with the auxiliary boom, the prepared stub and the cable to the station were fastened. The LP7 was ready for action! It now had to be proved whether the expectations were fulfilled.
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| The LP7 now in its full splendor |
The first attempts
yielded the expected results on 12m and 17m. The vertical dipole
was still at disposal as a comparison antenna. When switching
from the beam to the vertical, almost incredible differences
emerged on these bands up to 5 S-units. The VSWR looks likewise
very well, on both bands generally between 1.1:1 and 1.25:1.
There is naturally no direct comparison possible to the beam on
the other bands but purely subjectively I can say that the LP7 is
in any case better on 10 and 15m than the 3ele beam and on 20m at
least equally well. I can shore up my subjective estimate over
detours in comparison with my Lazy Delta Loop, because the
differences of the A3S to the Delta Loop are still a little in
memory.
I have recorded here a WAV file where V51AS can be heard on 12m in CW. I have
switched repeatedly from the LP7 to the vertical during his CQ
call. The difference can clearly be heard. The file was recorded
on May 28, 2001 at 08.00UTC on 24.895 MHz. I had one more QSO
with him in the evening of the same day on 12m SSB. To document
that also in SSB, I have recorded a part of the QSO with
switching between the LP7 and the vertical. Here now V51AS in SSB on 24.942 MHz at 16.10
UTC. The difference between both antennas is impressive!
I hope that I now still have long delight with this antenna and
that I will be spared by storms. A first test in this regard has
been given already. There were short blasts in a storm front with
approx. 90 km/h, whereby there were no problems.
The antenna is rotated by hand. I have therefore set the
standpipe on a portable-like fixture. The internal tubing sits on
the roof timbering and can be turned by means of a lever under
the standpipe fixture. The brake for ascertaining is not yet
matured. I have to think of something better, although the
temporary arrangement holds now already for 10 years! The antenna
is locked in the park position (direction south) with a bolt, so
that a sure hold at storm is guaranteed.
Thanks to Bernd - DF3CB for translation and final design!
