VK5RMG

UHF filters top, PRF1520 2M repeater with UHF Links below to Mt Benson and Naracoorte. VK5DJ three channel controller centre of link panel.
The cabinet for VK5RMG. No, the building doesn’t lean, the photographer does.

VK5RMG, located between Millicent and Mount Gambier is our main hub two metre repeater. It is located on The Bluff, approx. 200m ASL. We recognise the support of Gambier Electronics for the use of the hut and tower. Their help is much appreciated.
Lat.  37deg 43min 52secS     Long.  140deg  34min  12secE

The input is on 146.300MHz and the output is on 146.900MHz at 25 watts.

Although the repeater can be set for CTCSS control, it is normally open. A transmission on VK5RMG is relayed to VK5RNC, VK5RKN, and VK5RBT through UHF links.

UHF Link to Naracoorte on 442.375 MHz
UHF Link to Mt Benson on 430.475 MHz

The latest three channel controller has enabled us to go without the old audio bridge that served us for many years but proved difficult to set consistent audio levels across repeater and links.
Below the link transmitters are the cavities – six of them, three for the receiver with a notch at 146.900MHz to remove the transmitter signal, and three for the transmitter with notches on 146.300MHz to reduce noise from the transmitter entering the receiver.

The repeater has good coverage of the Lower South East of SA and some distance across the border into Victoria.

An early working bee to install antennas (Circa 2005)

The 2M transmitter runs 25 watts while the link TAIT transmitters run 4W into 10 element yagis pointing at Naracoorte and Mt Benson.

The main repeater antenna consists of two commercially made vertically stacked folded dipoles.

The new controller allows remote functions that include the transmission of a tune up tone of 1kHz tone at 3kHz deviation. This is invaluable for adjusting remote receivers for consistent levels across the network. In addition the new controller also has a better CTCSS decoder that may be activated or even changed in frequency if necessary.

Col VK5DK, Charles VK5HD and Andrew VK5KET make a happy picture at one of our working bees on site. Photo: VK5DJ

Generally CTCSS will not be in use but when there is persistent interference (usually from unstable TV preamplifiers in Mount Gambier) we will be able to lock the interference out and yet facilitate communication in the normal way.

Currently the CTCSS frequency is set for 91.5 Hz. It is good practice if users have 91.5 Hz tone activated on their transmitters at all times so they won’t be caught out when CTCSS is activated.

The Mk2 VK5DJ controller and ancillaries.

At top the main interface contains a PIC18F4620 providing level output on LED and status leds.

Centre the voice recorder (ISD1760 chip) driven by the interface board.

Bottom is the controller itself providing all control functions, audio amplifiers, DTMF and CTCSS.

All connections via I2C to front panel devices.

Three DB15 plugs on rear of chassis feed the two link devices and the main repeater.

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