Greetings fellow members,
The
VK2RCB Repeater has undergone improvements since I last spoke to you 2 weeks
ago. Since then I have done the following:-
- A Bandstop Filter has been added to remove a great
deal of FM commercial band interference. The Bandstop provides across the FM
band -40 dB of attenuation from 88 to 108 Mhz with a low insertion loss of
-1.3dB at 146.150 Mhz
- A
directional antenna with a gain of +6.8dB has been installed on the Receiver
and this provides a 120 degree radiation pattern to the south west of the
radio site. This antenna was chosen to afford an off axis attenuation of
-20dB from the commercial FM antenna systems that are located 35 Mtrs from our
radio site tower to the East.
The
combination of both these solutions along with our Band Pass Filter has
eliminated interference from all commercial FM stations and nearby Pager
systems as well.
The Directional Antenna and Band Stop Filter are
provided at no charge to the group, I have donated these items to the
group.
Critical analysis was undertaken of the receiver and
transmitter performance while on site last Friday. RF output power to the
antenna system is excellent at 42 watts and the receiver squelch is opening
at .38uV with 10dB sinad achieved at .49uV at the input to the filter
system.
The
attached Photo shows our filter arrangement inside the hut. The filter to the
far left is the Band Pass Filter and the other two are the Vari Notch Filters
that provide RX/TX isolation.
The
second Photo shows the antenna entry points to the radio hut and the
"Polyphaser" lightening protection fitted. Surge Mains Power Protection is also
fitted.
The
other two (2) photos are of the performance of the Band Stop filter as tested
prior to installation. The test frequency was 106.0 Mhz. It clearly indicates an
attenuation in the order of - 40dB.
The
repeater is operating normally and full IRLP and Echo Link facilities
are operational.
Preliminary coverage reports have confirmed all of the
Coffs Area coverage, Sawtell, Moonee, Toormina, Urunga, Snapper Beach
(south Urunga) and areas of Boggy Creek (west of Bellingen). Coverage
in Bellingen is also available in selected areas. Over 95% coverage of the
Waterfall Way is covered from the Highway at
Raleigh into Bellingen.
Coverage testes were undertaken using a standard mobile
installation of a quarter wave centre roof mounted antenna (Unity Gain) and
a RF output power set to 20.0 watts.
Further
coverage tests will be undertaken over the following weeks.
Regards,
Gary
Ryan VK2ZKT
Group
President
MNCARG
Inc
PH:-
66552990
