VK5RMG update July 2024

Following a number of visits over several weeks the repeater team have now found a workaround that prevents the trunking radio interference from taking over the system.

Maxwell has put a huge amount of effort into the problem over this time and he now has an excellent understanding of how the Philips PRF1520 operates. It should be said that this is a very complex radio as it can be used in many ways. There are dozens of configuration jumpers and they need to be just right for our particular usage.

The main change is to use the PRF1520’s internal CTCSS hardware at 91.5Hz.

In the past when VK5RPM was transmitting and mixing with two or three other transmitters the receiver would open and we would hear the interference. This was because the 91.5 decoder was inside the controller and audio (the nasties) were fed into the audio system even though the controller was not responding to the mute.

We have now activated the CTCSS detect in the PRF15 which means that if there is no 91.5 Hz tone, not only  is the mute not activated, but the audio is also inhibited.

The repeater operation is now less susceptible to the interference. It will not show up at all if communication is coming via our links but if the incoming user’s signal on 146.3 is weak, you will hear white noise in the background or may even cause the weak signal to drop out.

This is not a cure for the interference, it just means we will not be bothered by it and we’ll have some peace!

The cause of the interference is still being investigated.

Mystery at VK5RMG

The 2M repeater has an indicator if volts are getting low. A decreasing frequency set of 3 tones on the tail indicates that voltage is low at the controller (i.e. it’s working from the battery). A quick test using the telemetry remote control indicated the volts at the controller were down to 11.9V under TX load (probably about 12.4V at the battery). Strangely the beeps  would disappear and power was apparently restored after 1.00 pm and for the rest of the day.

The SA Power Networks did not indicate an outage and yet this puzzling pattern repeated for a number of days. What’s going on?

So on Wednesday 29/5/24 an intrepid group of Maxwell VK5AC, Jack VK5EBA and John VK5DJ made the trip. On site at 2:00 pm there was no sign of the beeps re-occurring. All the meters read correctly. The battery was being charged, the repeater was using the correct amps and volts from the 230V AC power supply. The mystery deepened.

Then Jack with his extra bit of height said “What’s this?” and pointed at a timer above his head that was used to shut off 230V AC and cycle the battery between midnight and 6 am.

That was it, the power outage last Sunday lasted about 7 hours and the mechanical timer stopped ticking during that time, so when power was restored following the completion of the SAPN work the timer was about 7 hours slow and thought it should cut off power between 7 am and 1.00 pm.

If only all problems could be fixed as easily.

Maxwell and Jack looking pleased with the result

Buy tickets in club lottery

The Club has again enrolled in the People First Community Lottery. All the money from your purchase of tickets goes to our club. It is their way of supporting community groups. By buying the $2 tickets you’re guaranteed to help SERG and if you’re lucky wouldn’t it be nice to have one of the cars, nice TVs or solar systems?

The link to access the community lottery is:

South East Radio Group Inc.

The prize list is pretty good and the odds are much better than Lotto.

Here’s the prize list. Click on the image for a better quality version.

Click on the image to see a better quality list

Remote station now available

The remote station (Yaesu FT991a) has been installed at the clubrooms and has 80M and 40M antennas active. It also has a dual band vertical antenna for 2M and 70cm. It is working well through the 2M repeater and also works on C4FM which will be a boon for those without a Yaesu C4FM radio.

Do not change to any other band as this could result in damage to the transmitter if you accidentally transmit.

Thanks to David VK5DG for installing the software into the Raspberry Pi Version 3B.

To access the station you only need your browser e.g. Firefox, Chrome or Edge  on your computer with a microphone and speaker (or headset). You can also use your phone. I chose this browser based operation so users did not have to install software.

In use, you access the radio by going to the website

The password will be provided at a club meeting, or by sending VK5DJ an email.

Here are the instructions on getting it working.  Copy the following URL into your browser.

Do not exceed 50% compression and ensure you set the power output to meet your licence conditions.

Questions to John VK5DJ

Naracoorte power supply issues again

From Peter VK5BE
Today, 23/3/24 Nick and I attended at the Naracoorte repeater site and found the following.
  • The standby current on the 12 volt power supply was reading 3.5 amps.
  • Switching off the mains power to the power supply resulted in the battery dropping to 11 volts when the repeater was in standby.
  • This suggested that the battery was faulty (It also felt quite warm)
  • We then replaced the 15 Amp Tait power supply with another that was not set to limit the output current.
  • The battery was then removed from circuit, resulting in the repeater running entirely off the mains powered supply.
  • We noted that the volts now remain constant under load at 13.5 volts.
  • The total load on the supply seemed quite high, reading 12 amps when both links and the 2m repeater were transmitting.
  • Site was left running on mains power only, with no battery back-up.

Note from John VK5DJ

Things misbehaved again on Sunday. Signals were passing through on the links but the Repeater itself was either not responding or weak with hum. My conclusion is that the power supply is not able to supply the 12 amps required without a battery filling in the gaps.

For the moment Tony and I have successfully turned off the VK5RNC repeater transmitter but allowed Alan VK5ZLT to continue to have access to the 2M system through the links at Naracoorte.

In the meantime Peter has found a better battery charging system and a source for a replacement battery. As it is the Naracoorte Amateur Radio Club (NARC) Repeater he will speak to Ross and propose a possible solution.

VK5RMG tower test

Due to the blocking of the 2M signals in the Mt Gambier direction at The Bluff, the club sought permission to put the 2M antenna for VK5RMG onto a different tower.

These photos show the working bee on 12  Jan 2024 when Leith (VK5FLAR), Peter (VK5BE), Nick (VK5NJS) and Col (VK5HCF) installed the twin folded dipole array on the ‘new’ tower. The tower is a guyed one and is currently used by a local FM radio station. We appreciate that the tower owners have allowed this experiment.

Our antennas are at about the 40m mark and have an excellent view towards Mt Gambier, Millicent and Naracoorte. Nick was the extraordinary tower climber while Leith provided the safety backup climber. Peter provided technical encouragement while Col was chief photographer.


Leith shouting encouragement to Nick above the second set of guys.
Ground crew: Leith and Peter
Dipoles in place

A further working bee on Wednesday 18/1/24 took place and the coax was run from the bottom of the ‘new’ tower to the VK5RMG room and connected to the cavities. Initial results in all directions are very positive and it seems to be similar to the signals obtained when we were on the Azicom tower. Mobile operation from Mt Gambier is again very usable. Reports are very welcome.

VK3RSW reconnected to network

We (Peter and John) spent a couple of hours at Mt Richmond today (6/12/23). We put a notch filter cavity in the receiver to remove the APRS. It didn’t work despite attenuating the APRS signal by 50 dB.

We put a passband cavity in the transmitter line to meet ACMA requirements.

We installed an improved FX365 tone decoder set to 91.5Hz into the controller.

By turning on the CTCSS for the repeater receiver we have been able to completely stop APRS from opening up the transmitters. This is working very successfully and it’s also stopping some occasional noise bursts from firing up the transmitters.

So the bottom line is that the repeater is now sitting there quietly. Peace at last!

The only downside is that everyone coming in on VK3RSW frequency will need to set CTCSS 91.5Hz in your transmitter. Most may already have this set because it is the standard for Australian repeaters.

VK3RSW is again connected to the SERG repeaters, we’d love to hear you come on and say “G’day”.

Interference on 2M repeater system

The interference you hear is due to APRS on Mt Richmond getting into the Portland repeater due to overload on the site.

Peter has tuned up a notch cavity and a bandpass cavity but due to the Hill Climb responsibilities we can’t do anything about it for a week or two. I’ve also modified a new board for the CTCSS to install when we go over there.

Here is a note I put on the Portland Facebook page.

We’re having trouble with the APRS getting into VK3RSW 2M repeater. This afternoon we’ll turn off the link to the rest of the system as it’s making the system over here unusable. We’re flat out with the hill climb at present so it may be a couple of weeks before we can get over there to put an extra filter in. We’ll also set up VK3RSW for the standard 91.5Hz tone access. At present a tone is not setup properly. We have a cavity filter tuned up for the receiver to try to overcome the overload situation, hopefully this will be all that is required. Another technical difficulty is that the APRS is radiating a 91.5Hz tone and this may make setting the tone on as an added precaution ineffective. If VK3 users would rather, we can turn off Mt Richmond altogether until we get over there. I’d appreciate your advice. For the Sunday broadcast we will turn on the link so people can hear the broadcast. The joys of setting up a new repeater, but I’m sure we’ll get there. Thanks for your patience.

VK3RSW installed

VK3RSW Mount Richmond 2m repeater now on air.

On October 15th, after almost 4 years of planning, negotiations and testing, the VK3RSW 2m repeater at Mount Richmond, NW of Portland, has been finally commissioned. With a RF link to The Bluff, the SE network has now been greatly expanded to include the coastal towns of Portland & Port Fairy, and inland to Heywood and Hamilton. This now extends the coverage area to over 400km from end to end.

The following are some of those that have contributed to this project.

  • Peter     VK5BE                 Project leader
  • Nick       VK5NJS                 Steelwork, fabrication, welding and painting
  • Brian     VK5VI                   Assembly of 2m repeater and link equipment
  • John      VK5DJ                   Repeater controller and cavity tuning
  • Steve    VK3ZAZ                Donation of stacked dipole antenna
  • Leith     VK5FLAR             Donation of link yagi antenna
  • Owen    VK5HOS               Donation of solar panels and batteries
  • Ron        VK5AKJ                Donation of solar controller
  • James   VK3JBM               IT support
  • Tim         VK3TIM               Site coordinator

Also, we wish to thank the following businesses

  • Multi-Metals for supplying all the steelwork
  • Aussie Broadband for the donation of the low loss coaxial cable
  • Baxter Hire for the use of their cherry-picker

Early signal reports indicate that the coverage has exceeded expectation.

We now look forward to an increase in traffic on the expanded linked network.

VK3RSW 2 metre FM repeater operational on Mt Richmond VIC