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Since everything looks to be progressing nicely, we
thought it timely to bring everyone up to speed with how the hardware is
coming along.
The Aerials
- The aerials are due to be erected sometime
next week (week commencing 21st November 2005). This work is being
performed by a professional aerial installation team, most of us in
the group are long past risking life and limb hanging from ladders
and suchlike! The installation will consist of a Diamond X200N at
the top of the mast giving approximately 3.8dBd of gain for the
repeater's receiver. The height of this receive aerial will be about
75 feet ASL, (45 feet above ground level). Approximately 8 to 10
feet below this will be a 0dB gain folded dipole that will be used
as the TX antenna. This aerial will be fed with 5W power giving
7dBW. Both aerials will be fed with Westflex W103 lo-loss coax.
The Filter Set
- We're in dialogue with the GB3DX group who
can supply us with two Aerial Facilities Ltd "Beer Barrel" cavities.
It is hoped that these filters will be installed once the aerials
are up. Since we've decided on two aerial working this makes the
filter arrangement a little easier to the point where, (it is
hoped), that two filters will be sufficient. In theory, with the low
power level, vertical separation of the aerials and the de-sense
level of the repeater's receiver, the sums work and say it should be
ok.
The Repeater
- We're lucky in that we have enough kit for
two repeaters. The backup repeater is already built and consists of
two Motorola GM300's. The repeater proper is a Tait T377 / T375
combination. Work on this is well underway, and is hoped to be
completed shortly.
The Logic
- We've decided to use an ICS controller. Their
web site can be seen by clicking
here. We have
their "Linker II" model, we need the functionality of the Linker II
for when the repeater is internet linked. This logic is already
connected to the GM300 repeater and is working very well.
Power / Batteries
- The repeater will be powered from the mains,
but a UPS will also be fitted. At this time, until we complete some
tests, we cannot predict how much time the UPS will keep the
repeater on air in the event of a power failure.
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