VK5RSB Maintenance Day – Battery Backup & 6m Antenna

Since the statewide power blackout last year, AREG has been assembling replacement parts for the battery backup system on our VK5RSB repeater system. Now that this last weekends excitement is over, I am now able to compile and present a detailed report on the working bee at the VK5RSB repeater site at Summertown.

Working bee members,

  • Ben VK5BB
  • Colin VK5ACE
  • Paul VK5BX
  • Adrian VK5ZBR
  • Rod VK5UDX (both Rod and Adrian were on an official task at the site in their employment but were able to spend time assisting at the site)
  • David VK5MDF (invited visitor from NERC)

The aim of the working bee was to replace the cavities on the 23cm repeater, reinstate the battery backup system for the 70cm repeater (disconnected several years ago when the repeater was replaced with one requiring 24v input) and install (finally) the permanent replacement 6m repeater antenna (delayed multiple times in the past due to weather).

Work completed successfully included

23cm Repeater:

  • 23cm duplexer fine tuned (thanks to Paul VK5BX and his Specan/tracking generator)
  • the old 23cm removed and the new one fitted, tested into the antenna and live on air, all good

70cm Repeater

  • the 12 volt to 28 volt inverter installed into rack and wired in,
  • RF power out of 70cm when on battery backup has been set to 30 watts (normally 75 watts whilst mains power is active)
  • repeater tested on battery backup, draws just on 8 amps and puts a “beep” every 60 seconds to identify unit running on battery backup.
  • whilst on site, Paul took the opportunity to “Sweep” the VK5RSB 70cm antenna, return loss was good BUT it was identified that there IS a problem, a ringing or ripple on the return loss sweep, possibly due to a faulty connection in the line. We believe that the problem is most likely the coax connector on the top end of the LDF 450 coax, as this was not serviced or replaced when we changed and fitted the new antenna a couple of years back.This means another working bee, when the weather for working at the top of the tower is conducive.

6m Repeater

  • during the above work activities, Adrian and Rod were able to swap out the old 6m repeater antenna and install the new antenna. Once the new antenna was connected, a return loss sweep was done and all looked very good.
  • with the the 6m repeater reconnected to the antenna, it was still “going nuts” keying up very regularly on “spurious” Checks of the spectrum could not identify any specific signals the could be causing this other than the high noise floor. So Adrian wound the mute setting a bit higher and this fixed the regular intermittent keying of the repeater. (subsequent observations and reports are that the 6m repeater seems to be working very well and is generally quite when not being worked)

A big thank you to everyone who contributed to the work at VK5RSB. I am sure it will improve service for all amateurs in the greater Adelaide Metropolitan area.

Horus 45 Balloon Flight for WIA Convention 2017 – Preparation Underway!

The Amateur Radio Experimenters Group is please to announce that it will be supporting the WIA AGM & Convention weekend with a balloon launch. This launch will take place from Hahndorf Oval, as part of the “Come and Try Radio” activities day to be held on Sunday 21st May.

This event is aimed at promoting the many different facets of Amateur Radio and giving people the opportunity to learn about how to get involved. AREG will be manning two complete tracking stations at the event, one a fixed ground station and the other will be one of the chase cars decked out in the equipment we use to chase balloons in.

The main aim is to get more people interested in tracking the balloons!

 

 

Flight Payloads

The payloads are still being finalized, as the jet-stream has returned and there are concerns that the flight could be carried downrange much further than planned.

Balloon Repeater Frequencies

The balloon repeater will be heard on:

  • INPUT: 145.775MHz with 91.5Hz CTCSS (+/- thermal drift of the receiver)
  • OUTPUT: 438.850MHz (+/- thermal drift of the transmitter) – 0.8W into 1/4wave omni

NOTE 1: The VHF frequency has changed this flight to avoid harmonic issues with the Wenet imaging payloads

NOTE 2: The repeater is built out of a received designed to receive Narrow FM (12.5kHz bandwidth) not the usual 25kHz wideband FM that amateurs use. Please keep your deviation down so that you can pass through the repeater without it closing it’s mute.

To transmit to the balloon at the maximum range of 800km (once the balloon reaches 100,000ft ++) you should only need approximately 10-20W and an 2-4dB gain antenna.

Receiving the balloon at 400km range in a handheld environment should be achievable, but to hear the repeater at the maximum range of 800km you should expect to need a 10dB gain Yagi for a 0.4uV capable receiver and 2dB feeder loss

This setup is much the same as the LEO satellites but without the high speed Doppler shift.

PLEASE MAKE SURE YOU CAN HEAR IT BEFORE YOU TRANSMIT!

Other Balloon Payloads

Other payloads being flown on this flight will include:

  1. our standard 100bps 7N1 RTTY telemetry transmitter on 434.650MHz, and
  2. the Wenet imaging payload which will downlink on 441.2MHz at 115Kbit/s, and which will stream HD photos during the flight.

Images can be seen (here).

Tracking will again be available via www.habhub.org

Flight Time and Launch Location

If you would like to learn more about how to get involved in tracking the balloon, take a look at the following resources on the club website, or come on down to the launch on Hahndorf Oval. Preparations will begin around 1.00pm, with liftoff planned for 2.00pm. (See the location marked “Amateur Radio Come and Try Day”.

 

WIA AGM & Convention Special Event Callsign to be Net Control on the balloon repeater

The WIA AGM & Convention special event call sign VK5WOW and VI5WOW will be heard via the balloon repeater during the event. Contacts with VI5WOW and VK5WOW through the balloon will qualify for the award certificate.

Full details of the Convention 2017 award are available via  www.wia.org.au/members/wiaawards/agm2017/

RPM200 Canoe Spotting Training Day & Picnic – Murray Bridge – Saturday May 6th

UPDATE: The event went very well and everyone who attended spotted all of the canoes as they went by in both directions. Well done team!


Each year the Amateur Radio Experimenters Group supports the Marathon Canoe Club of South Australia’s River Paddling Marathon event as it travels from Berri to Morgan, a distance of over 200km, during the 3 day long weekend in June. (Read more about this event from the 2016 event report (here).

To prepare for the event, one of the exercises AREG runs is a canoe spotting practice day in conjunction with the Back to Back canoe race in Murray Bridge. Instigated last year  as a training day for spotting canoes, we will again be venturing out to Sturt Reserve, Murray Bridge on Saturday May 6th.

The day will consist of AREG teams of two being set up with ~50m between them. The goal will be to see who can spot the most canoes (or best of all who can spot all of them). The canoe participants will be passing the location multiple times, so you will need to be good at tracking multiple moving targets.

Why are we doing this? To help you hone your skills at spotting canoes on the river. The participants of this event could be over the far side of the river, so spotting their numbers is something to be practiced so that when we have to track each and every canoe past a checkpoint at the RPM we are equipped with an understanding of the gear required to do so accurately. A day sitting beside the river isn’t exactly a bad thing either, with a sausage or two sizzling on the BBQ!

Times and Places?

Members participating in the practice day should plan to arrive in Murray Bridge  at 12:00pm. The first canoes should be past shortly after 1:30pm and the event should be over by around 4-5pm.

Things to bring:

  • Table and chairs
  • Optical Amplification (Binoculars, telephoto camera, telescope etc)
  • Pen
  • Handheld
  • BYO Food & Drink

The afternoon is as much a social get together as it is a training exercise, so even if you are not coming to the RPM, who not come down and spend an afternoon by the river having a picnic?

Where will you find us? Look in the eastern end of Sturt Reserve. Liaison up close will be on 439.025 MHz FM Simplex.