All posts by Waratah Swinton


Australia’s Highest DSTAR Repeater is now operational

439.300MHz -5MHz VK4RBM B

The Blue Mountain repeater site is without any doubt Central
Queensland’s best amateur radio repeater location. Surrounded by
thick tropical rainforest slopes and standing at 1040m, this truly is
a remarkable site.

Having such a picturesque, high elevation site does not come without other
challenges, the main one being access. The answer
is the help of a Jet Ranger helicopter and some superb piloting skills.
Once the weather cleared, we jumped into the chopper and cruised up to
the site. As we approached the site, the tower could be seen poking out above
the thick rainforest. The landing site is a small rocky area with

a tiny patch of grass. As we started to land, the view disappeared and we were
surrounded by trees, then we touched down, unloaded the gear, and the
chopper departed.
We had a short time on site to install the new DSTAR,
APRS, 3G modem and solar regulator. The work was completed in
record time, and the chopper came and picked us up before the clouds
rolled back in.
vk4rbm-tower2-final 20170609_084012

Blue Mountain Site

Our antennas

Our antennas

Check out VK4RBM-3 on


The Blue Mountain DSTAR repeater is running on test, ready to be taken up to site. We are using APRS telemetry data to monitor and control the DSTAR repeater using the WX3in1 APRS modem. The analog inputs are being used to measure:

  • Battery voltage
  • Transmitter cooling fan current
  • Raspberry Pi and DVRPTRv1 current
  • DSTAR transmitter temperature.
(see VK4RBM-3 on
The fan current and transmitter temperature is particularly handy as it shows equipment utilisation. When the repeater is active with users talking on it, the transmitter temperature rises, so the fan cycles in. Another benefit of monitoring the temperature on the transmitter is that a sudden spike in temperature will indicate a fan failure. Our design includes two fans, a main and backup that are both temperature controlled. These fans can be turned on and off independently.
The wxbits output module is being used to control some repeater functions. The repeater transmitter can be disabled using the transmit inhibit function. The repeater output power can also be controlled. The transmitter radio channel table has two channels programmed in; one at 25 watts and the other at 5 watts. The wxbits output module allows the radio transmitter channel to be changed remotely between high and low power. The low power channel uses less current than the high power channel. This is handy when the site battery level falls because you can keep the site operational for longer by changing the transmitter to low output power.
We have also included a selcall activated relay. The 12V bus that supplies the Raspberry Pi is fed via the relay in its relaxed state. When a selcall is sent to the transmit radio the relay is energised, disconnecting the 12V bus for 5 seconds. This feature is used to remotely power cycle the Raspberry Pi in the event that it locks up and becomes unresponsive.
A 3G modem is being used to provide internet access for the Raspberry Pi. The 3G modem has serial ports. These serial ports have been setup to provide a serial tunnel so that we can monitor and control the Plasmatronics solar regulator. The advantage here is that we can closely monitor the solar and battery condition. This also provides yet another method to hard reset the equipment as the load control from the solar regulator can be controlled remotely.
The 3G modem also provides additional functionality using its controllable dry contacts. Each piece of equipment can be individually turned on and off using text messages or the web interface. The benefit of this is that it provides an additional tertiary power cycling feature, should a hard reset of the Raspberry Pi or APRS modem be required. It also allows enabling either the main or backup fan.
vk4rbm_tx_radio1  vk4rbm_tx_radio2

As you may be aware our VK4RBY Black Mountain site was broken into a few months back and some gear was stolen. We are now backup and running on DCS028Q with a 70cm DSTAR repeater. Work is underway to install a 2m multimode repeater at this site in the coming months. Historic data usage shows we use about 1.5GB per month. We are testing a prepaid Optus simcard to provide internet access. The Optus deal is good value, $130 for 22GB with a 2 year expiry.

RBY70cm-3 RBY70cm-2

Alright, get your head out of the sand. Stop questioning why we should do one digital mode over the other. Multimode repeaters are here. It is with great excitement that we can announce the Mackay area multimode repeater is now operational. This really is a great achievement by all the volunteers who helped this get off the ground. We encourage all other clubs to follow a similar direction and put up a multimode repeater that can fulfil the needs of just about every digital voice mode there is. There really is no excuse to not put up a digital repeater. We have been mainly testing our repeater on DSTAR and P25, and by all reports it is working great. Our setup is using a Tait TB8100, and Odroid XU4, and MMDVM modem. We also have the added bonus of a DVRPTR v1 modem also connected to the Odroid CPU. The DVRPTR v1 runs a standalone 70cm repeater and our 2m frequency runs as a multimode repeater. The modes supported on our 2m repeater are DSTAR, P25, DMR, and YAESU C4FM.

147.075MHz +600KHz

rpt 1 VK4RSA C

rpt 2 VK4RSA  G


vk4rsa-rack2 vk4rsa-rack1 vk4rsa-towermmdvm_vk4rsa

VK4RBX – The Knobby, Ipswich has now been upgraded to a mmdvm based multimode repeater. DSTAR, C4FM, p25 and DMR  are all supported. DSTAR allows connection to a reflector for 10mins before timeout disconnect.

VK4RBX  C          146.7875MHz             -600KHz

This repeater is not linked to the closed DMR MARC system. The DMR side is using brandmeister network. This network supports most DMR radio’s and allows remote DMR hotspots such as dv4mini’s to connect to the 4805 reflector.



The Mackay area multimode repeater is another step closer. This afternoon we commissioned the multihop microwave link that provides internet access to our remote repeater site. This microwave system links VK4RUS at Sarina beach Rd to VK4RSA Jordan Creek Sarina and provides internet access to both sites. The network access links DMR, P25, DSTAR and C4FM to internet reflectors and also allows us to remotely monitor system performance. Weather camera CCTV will be added in the coming weeks with both sites having a great view of the Sarina area. Local hams are reminded to program the new frequency into there radios 147.075MHz +600KHz.

vk4rusp2p1 vk4rus2vk4rsa