Assisting in the maintenance of VK6RAV
repeater tower and the installation of the antenna..
VK6RAV -
Avon
Valley Repeater
Maintenance 2014
The installation of the 2 metre band antenna was only
part of the overall work carried out at the VK6RAV repeater site in 2014. The largest activity was in
fact the replacement of all 36 tower guy wires. Below is an edit
collection of progress email report issued after each
activity.
Saturday
15/02/2014
The
working bee on Saturday 15/02/2014 has replaced the lowest group of
guy wires successfully. The work was a little slow as we were still
refining our techniques’ with last guy wire of the group taking
less than 20 minutes. See photos of guy terminations.
Newly installed
guy wire
Saturday 22/02/2014
The working bee on
Saturday 22/02/2014 continued replacing the lower guy wires with a
significant improvement in productivity. The lowest guy wire group
was replace on the previous visit and an additional three guy wire
groups being replaced on the on this visit. My rough estimation
suggests that this is approximately 25 – 30% of the project
completed. All members of the crew were happy with the productivity
and safety of the techniques.
Antenna
inspection
The
locals
Saturday 29/03/2014
The
working bee on Saturday 29/03/2014 was intended to continue
replacing the remaining guy wire; however work was slow as we are
encountering logistical challenges now that we are work near the top
of the mast. The first issues was the entanglement of the haul rope
in a newly attached guy wire that finally forced the ground crew to
un-attach the ground end of the guy to untangle the rope. Finally
despite an ideal start to the day winds picked to an unacceptable
level resulting in aerial activities being cut short.
The
day achieved some early essential retentioning work on the guy wires
and the tower was checked for straightness and verticalness with the
theodolite, which surprisingly showed that the top of the tower was
only out by 3” (75mm). The aerial work achieved the installation
of three guy wires at the Guy Wire Group 10 level.
Looking serious at
25m above the ground
Checked for straightness and verticalness with the
theodolite.
Saturday
05/04/2014
The
working bee on Saturday 05/04/2014 installed the final guy wire;
that is all 36 guy wires have now been replaced with 18 of the
original guy wires to be cut away at a future working bee. The
decision to stop removing existing guy wires are went was made at
the half way level to provide additional tower stability for the
higher tower work as there is quite a bit of disturbing movement and
twisting in the tower’s upper levels.
The
final 6 guy wire installed on the 05/04/2014 working bee were
obviously the longest and we had selected a heavier 5mm diameter
wire as compared with the 4mm used on all the lower guys, this
created a significant handling issue so we determined that it would
be more efficient to cut and terminate all the guy wires on the
ground and haul them up the tower in quick succession to be attached
to the tower. The ground attachments would be made once all guy
wires were attached to the tower. As the roll of wire was an unknown
length there was a possibility that we did have enough and so it was
crucially important that the pre-cut guys didn’t use much
additional wire beyond what was actually needed. Norm Fox and I had
independently calculated the precise wire lengths of the proposed
guy wires and despite a bit of doubt and a lot of pressure from Jim
Nicol and Peter Hackett we stuck to our calculations and were proven
to centre metre accuracy; well 30cm accuracy.
Guy
wire group
Distance
from tower base to ground attachment (Mtr)
Tower
attachment above ground (Mtr)
Guy
wire length (Mtr Rounded up to 3 decimal place)
Guy
wire length plus 5m termination tails (Mtr Rounded up to 1
decimal place)
1
20.22
4.790
20.780
25.8
2
20.22
9.280
22.248
27.3
3
20.46
13.770
24.663
29.7
4
20.46
18.260
27.424
32.5
5
20.72
22.750
30.772
35.8
6
20.72
27.240
34.225
39.3
7
30.16
31.730
43.777
48.8
8
30.16
36.220
47.133
52.2
9
30.4
40.710
50.809
55.9
10
30.4
45.200
54.473
59.5
11
30.66
49.690
58.388
63.4
12
30.66
54.180
62.254
67.3
Guy wire
cutting and terminating
Guy wire tensioning
Wednesday
23/04/2014
A
working bee of opportunity was carried out on Wednesday 23/04/2014
to remove the existing commercial antenna at the top of the mast and
install the new 2 metre band collinear antenna. Despite similar rope
hauling problems that have plagued previous work at and near the top
of the tower I’m am extremely pleased to report the new antenna is
now installed and functioning perfectly. Checks around the district
including the
Perth
suburbs have confirmed radiation pattern modelling. Peter Savage
(VK6YV) reported a 2 to 3 ‘S’ point improvement in the repeater
signal strength at Wanneroo and we have had other signal reports
suggesting similar strength improvements’.
We
are all very keen to hear any signal reports from various locations
and comments about the repeater’s performance in general, so
please send to this email address and enjoy Western Australian’s
best coverage 2 metre band repeater.
Video of the removal of the unused
commercial antenna array and the installation of the new 2m collinear
antenna.
VK6RAV coverage foot
print based on typical mobile radio set up.
Saturday
10/05/2014
Working
bee carried out on Saturday 10/05/2014 to cut the existing guy old
guy wires off a the ground attachments and carry out tensioning of
the new guy wires now that they were carrying the full load.
Initially all 36 guy wires were checked and adjusted to achieve a
10% of the wire breaking load. The tower was then checked for
straightness and various wires were slackened while others had there
tension increased until the tower was acceptably straight and all
guys were at the desired tension of 10% WBL.
With
the lower half of the old guy wires having been removed early in the
project the remaining upper guys were to be cut free and removed
however as I climbed towards the half way level a rain cell moved
across the site resulting in the aerial activities being call off
for the day after a hasty and wet retreat from the tower. All good
clean fun……
