AREG’s New 160m/80m Contesting Portable Antenna – Progress

Update – July 12th: Mounting of the tuning capacitor and motor drive is complete. Just a few more things and we will be ready for final assembly and tune up!


A group of members inside AREG, inspired by Steve VK5SFA’s success with his transmitting magnetic loop antennas have banded together to construct for the club it’s own 160/80m TMLA, specifically designed to be portable. It is able to be knocked down into components that can be packed into the back of a station wagon.

Significant progress was made today in assembling the antenna as we had hoped to have it ready to try at the IARU HF contest next weekend. We didn’t quite make it unfortunately, running out of daylight before we completed construction. However, we are now planning another session next weekend with the goal being to have the antenna finished and ready to run for the Trans Tasman Low Band Challenge contest the following weekend.

The club’s version of Steve’s antenna is using LCF78 coax instead of the wave-guide, with the vacuum capacitor mounted inside a water proof ex-camera case (great for transport and moisture proofing). The frame is made out of laminated bamboo broomsticks and a timber hub arrangement with the frame held together through compression provided by 8 ratchet straps. The aim is for the antenna to be suspended from a tree (or trees) at least 1 loop diameter above the ground (to increase it’s efficiency). It has been designed to accept 400W input power as well to overcome the efficiency issues these antennas can have.

Today’s construction efforts were led by Steve VK5SFA, Grant VK5GR and Scott VK5TST. The project wouldnt have been possible without generous donations from Steve VK5SFA, Peter VK5KX and Trevor VK5YFR.

The next steps are to complete mounting the motor tuning drive, do some structural adjustments to the frame, assemble the coupling loop and then test the antenna. This work will be completed next weekend, so keep an ear out for us during the TTLBC Contest on July 15th on 160 and 80m using our Transmitting Magnetic Loop Antennas!

AREG operating WIA HQ Station VK5WIA in IARU HF Championships

UPDATE: Over night crew working hard, band conditions difficult as usual…


AREG is pleased to announce that it will be fielding the operators to again run the WIA

VK5WIA in 2016

Headquarters Station for the 2017 IARU HF World Championships. The station will be run from the QTH of Chris VK5CP in the Murray Mallee region of South Australia. It is planned to have 2 transmitters on the air continuously at least. This year we are also hoping to get a 160m antenna and a couple of options for 80/75m antennas working from the site as well.

So look out for VK5WIA during next weekend and work us for headquarters station multiplier points! The Contest Rules are available from the ARRL Website.

Horus 44: Flight Report – Riverland BRL Field Day

On April 22nd 2017, the Amateur Radio Experimenters Group conducted an Amateur Radio focused balloon launch from the Riverland Radio Club’s VK5BRL Weekend event at Overland Corner Hotel in the Riverland. This launch was carried out to bring some interesting amateur radio based experiments to a new audience, and also to encourage more tracking stations to take part in Project Horus from the Riverland region (which is often a landing ground for the flights from the Adelaide Hills).

Ground Control

The launch campaign began at 9.00am with Bob VK5FO and Ray VK5RR helping Ivan VK5HS set up the balloon ground control station at the BRL Weekend event.

Horus 44 was the first flight of a new 2m/70cm voice repeater so we also were making contacts through the balloon using the VK5WOW special event callsign throughout the flight, promoting the Wireless Institute of Australia’s AGM which was being held in VK5 a few weeks later.

Launch Crew

Meanwhile the ground crew started preparations to launch the payloads. AREG members Matt VK5ZM, Mark VK5QI, Grant VK5GR, Darin VK5IX and Kim VK5FJ worked on assembling the payload train and filling the balloon with helium.

The predicted flight track was to take us east, to land tot he north west of Renmark. We certainly hoped is would follow that track, as there were many inaccessible obstacles in the Murray River marshlands area.

Lift Off

We were going to find out soon enough! Lift off was a text book effort, and straight away people were accessing the repeater, able to make contacts with VK5WOW. The only issue noticed early on was that the repeater’s receive filters were very narrow, enough to cause the mute to shut if you spoke to loudly. Even with that issue, contacts streamed through think and fast.

Once in the air, the repeater ran hot. The following stations made contact with VK5WOW via the balloon:

VK5WOW Log via Horus 44
Call Date-Time Mode
VK5ZD 2017-04-22 03:28:00 2M PH
VK5SFA 2017-04-22 03:26:00 2M PH
VK5GR 2017-04-22 03:25:00 2M PH
VK5APW 2017-04-22 03:19:00 2M PH
VK5DJ 2017-04-22 03:14:00 2M PH
VK5ZEA 2017-04-22 03:08:00 2M PH
VK5KC 2017-04-22 03:01:00 2M PH
VK5PJ 2017-04-22 02:59:00 2M PH
VK5ST 2017-04-22 02:55:00 2M PH
VK3BQ 2017-04-22 02:50:00 2M PH
VK5LOX 2017-04-22 02:40:00 2M PH
VK5AKH 2017-04-22 02:39:00 2M PH
VK5FDJW 2017-04-22 02:38:00 2M PH
VK5DF 2017-04-22 02:37:00 2M PH
VK5SFA 2017-04-22 02:35:00 2M PH
VK5QI 2017-04-22 02:33:00 2M PH
VK5KX 2017-04-22 02:32:00 2M PH
VK5FANA 2017-04-22 02:30:00 2M PH
VK5MTM 2017-04-22 02:29:00 2M PH
VK5SA 2017-04-22 02:25:00 2M PH
VK5ZTJ 2017-04-22 02:24:00 2M PH
VK5TS 2017-04-22 02:23:00 2M PH
VK5ZEA 2017-04-22 02:22:00 2M PH
VK5DJ 2017-04-22 02:21:00 2M PH
VK5ZX 2017-04-22 02:20:00 2M PH
VK5GR 2017-04-22 02:18:00 2M PH
VK5ST 2017-04-22 02:16:00 2M PH
VK5DF 2017-04-22 02:15:00 2M PH
VK5ZAR 2017-04-22 02:13:00 2M PH
VK5BB 2017-04-22 02:12:00 2M PH
VK5OI 2017-04-22 02:10:00 2M PH
VK5AW 2017-04-22 02:09:00 2M PH
VK5ZK 2017-04-22 02:08:00 2M PH
VK5SFA 2017-04-22 02:06:00 2M PH
VK5ZTJ 2017-04-22 02:04:00 2M PH
VK5FANA 2017-04-22 02:01:00 2M PH
VK5LOX 2017-04-22 02:00:00 2M PH
VK5NE 2017-04-22 01:57:00 2M PH
VK5ZT 2017-04-22 01:55:00 2M PH
VK5DJ 2017-04-22 01:52:00 2M PH
VK5MRE 2017-04-22 01:50:00 2M PH
VK5FD 2017-04-22 01:50:00 2M PH
VK5PAS 2017-04-22 01:49:00 2M PH
VK5FMAZ 2017-04-22 01:48:00 2M PH
VK5LA 2017-04-22 01:47:00 2M PH
VK5AW 2017-04-22 01:46:00 2M PH
VK2EF 2017-04-22 01:45:00 2M PH
VK5ZAI 2017-04-22 01:44:00 2M PH
VK5FO 2017-04-22 01:43:00 2M PH
VK5PE 2017-04-22 01:42:00 2M PH
VK5AHZ 2017-04-22 01:41:00 2M PH
VK5FTAZ 2017-04-22 01:40:00 2M PH
VK5FBJC 2017-04-22 01:39:00 2M PH
VK5RR 2017-04-22 01:38:00 2M PH
VK5TRM 2017-04-22 01:37:00 2M PH
VK5ZM 2017-04-22 01:36:00 2M PH
VK5GR 2017-04-22 01:35:00 2M PH

The repeater footprint continued to expand, and just reached Melbourne before the balloon burst.

WENET brings Superb Pictures

In addition to the voice repeater, the WENET camera payload also flew collecting stunning images of the Riverland region from the air.

This slideshow requires JavaScript.

Chase & Recovery

Meanwhile the chase teams had driven to Renmark and were watching intently as the balloon progressed along its path.  The two AREG teams were joined this time by Peter VK5PE and a crew from the Riverland Radio Club. The local knowledge they brought to the chase was invaluable!

At one stage we became quite nervous as it appeared it may actually land in the marshes. However, the winds once again became favorable and the landing zone looked very good indeed.

Recovery occurred after a short hike into a local conservation park, but not before we watched the balloon descend gracefully from about 1500m elevation!

Flight Statistics

The fight track for Horus 44 shows that there were fairly light high altitude winds on this day. Once clearing the ground winds the flight profile was remarkably vertical.

The detailed flight statistics are:

Horus 44 - BRL Weekend Amateur Radio Launch - Flight Statistics
Metric Result
Flight Designation: Horus 44 – BRL Weekend
Launch Date: 22/4/2017 01:36:17 UTC
Landing Date: 22/4/2017 04:25:41 UTC
Flight Duration: 2 Hours 49 Minutes
Launch Site: -34.153467 140.339623
Landing Site: -34.107695 140.651783
Distance Traveled: 29.1 km
Maximum Altitude: 29,953 m

This time we saw major contributions from many of our ground stations too. The following pi-chart shows who collected telemetry for this flight.

Conclusion

It was a very successful flight! A huge thank you again to everyone who was involved, and in particular to the Riverland Radio Club for the invitation to come and fly from their back yard. Thanks also to the AREG members who traveled and stayed in the Riverland to fly Horus 44, with a special thanks to Sharon VK5FSAW who once again helped with logistics through catering the lunches for those chasing the balloon!

LilacSat-1 HowTo

Mark VK5QI, and I have recently documented the set up and use of a receiver for LilacSat-1.

This cubesat has a 2m FM uplink and a 70cm digital down-link that uses a custom modem and Codec 2.

Our documentation is targeted at anyone with a laptop running Ubuntu 16.04 (though other versions may work too), a RTLSDR, LNA, UHF antenna, an Internet connection, and a few hours of time.  We have written several scripts that help install and build all of the software you need – in particular GNU Radio.

You can find everything you need here.  LilacSat-1 will re-enter in August, so time is of the essence!

73, David VK5DGR

AREG Members go Fox-Hunting at SERG Convention

This year, Adrian VK5ZBR again went down to Mt Gambier to participate in the South East Radio Group Convention with his family and Mike VK5AGI. The highlight of the convention is the annual round of the Australian Fox-Hunting Championships. Here is their story….

Hi All
I thought I would share our weekend at SERG Australian Fox Hunting Championship 2017.
 
Team Moose (aka VK5ZBR) had 4 members:
  • Mike VK5AGI – driver, ARDF
  • Adrian VK5ZBR – DF & ARDF
  • Kerry (XYL) – navigator & ARDF
  • Alayna (harmonic) – ARDF, navigator and playground critic
 Kerry now with last year’s hunts under her belt is the navigator. This year, a child seat was also fitted to the team Moose car, with Alayna a full time member this year!
There were two other VK5 teams also participating:
  • VK5TV Bevan and his wife and
  • VK5FAB (Ken and Paul Burns with extended family).

The FAB team this year was competing in all hunts.

Our equipment
This year we were not sure how we would go with one navigator as its quite a
difficult task. Kerry would be dealing with paper maps, Ozi Explorer and Google
Map Pro for the first time.
I also decided to try the SDR play on my new 12inch Chuwi tablet, this was a carry on from last years 10in tablet. The SDR was only used for detecting the fox when we were in close proximity. I had no antenna on the SDR so the signal had to be extremely strong. Again the SDR is not very useful for direction finding because of the processing delays. It’s great to identify the signal your listening to though.
 
I again used my Icom R10 and trusty ammo box home brew DFing radio I built in 1994.
 
Saturday
 

Adrian and Alayna Hunting Transmitters

Event 1

This event was the 10 Leg ARDF in Marist Park (crater), very hilly and great to hide foxes. Our team split up into 2 groups, Mike then Kerry, Alayna and I the other. I was teaching Alayna and Kerry ARDF. We had two hours
to complete the hunt. We did the hunt at a pace Alayna could do. Surprisingly we got as many foxes as I did last year on my own.
 
Event 2

The 4 leg CW FM transmitters on the same frequency with CW ID’s in any order. They come up at 30sec intervals. We learnt our lesson last year and Mike made two timer boxes with 4 colour LED’s on it. We would know each fox by its

Teams at the start of event 2

colour. This hunt is in the Caroline Forrest near Hells hole. We finished all the legs just on time. The last leg being the yellow colour took us nearly 1hr. It was located very high and clear giving a massive signal that always appeared to be closer than we thought. Yes we got bogged once on the blue leg but we recovered in 5min with a shovel.

 

One of the fox transmitters in Event 2

Event 3

This was the famous Wayne Kilpatrick Night Hunt (5 Legs) this will be Alayna’s first night hunt. She was a bit scared of the forest at night. This hunt is fun and can break you or your car (both which has happened in past years). Just to finish the night is a success. This year we saw plenty of kangaroos, and even a wombat. No UFO’s this year, however.
 

Leg 1 the 2m fox was surprisingly

Kerry & Alayna on the night hunt

easy, Kerry had a bit of an orientation problem for the first 5 minutes but got her bearings after that. Remember she’s using a topographic map and driving a PC with Oziexplorer and Google maps pro. We actually drove straight to the fox, which was just over the border in Victoria, with only one way in.

 
Next was Leg 2.  Oh damn, we can’t hear the signal! We switch to SSB and I can just make out something and head in the general direction. Lots of radio chatter about the fox not transmitting. After quite a few km the signal went from in the noise to s9 plus.
The fox announced his coax was faulty, NO JOKE! Lucky we were heading in the
right direction. Thank you again R10 in SSB mode!
 
Leg 3 we could hear with no problem but when we got closer we had issues with
many reflections. I was becoming a bit concerned so began to get-out the car with the sniffer antenna to get bearings. This took a lot longer but it all made sense when we found the fox hidden in a bush. The railway line was next to him and re-radiating his signal. I hate railway lines!!
 
Having found Leg 3 it was on to Leg 4. This is a nasty 6m band hunt! I had fixed up the loop days before and re-calibrated it. I was amazed how well it was working again. I could work out the direction with in 10deg. The trick that worked was stopping in line with the road and taking bearings. Kerry would plot this on the paper map and we drove nearly right up to the fox. The time was 9.30pm and I thought wow were doing very well with one leg to go. Alayna, however, checked out for the night so Mum lost her helper.
 
Leg 5 10m. One of the most difficult bands to hunt on in a pine forest! Why, oh why didn’t I check the loop before we left!! We could here the piccolo signal and I was having issues determining the direction. This loop has a better peak in one direction, and it didn’t feel right! So we did some driving to determine which way was
correct. Kerry plotted my directions and we ended up in Piccaninnie Ponds
Conservation Park near the beach. Kerry said how far do you think it is, I said far.
She said well it’s not in the ocean. We realized my bad gut feeling my DFing was 180 deg out had come true. So, back the other way north through to the township of Donovans.
 

This is when it got interesting, some

Mike VK5AGI in the drivers seat

nutter in a car coming the other way drove down the center of the road with his high beams on. This car then proceeded to come over to our side and Mike had to drive off the road not to hit him. This woke us up and we forgot about the hunt for a while.

Eventually, we got to the location that Kerry wanted to get to far north on the intersection of the princess highway. The signal was still north but not getting stronger. I made up my mind something is still wrong. I got my test transmitter out and tested the loop. Sigh, it was still wrong! When I looked up the loop had slipped 45deg at some stage. Damn! A bit of bending and the loop was re-aligned. The direction was now pointing back towards Mt Gambier….
 
Kerry determined this was logical for the last leg and I knew it was high up after all
these km’s. So we just drove back that way and quickly the signal got stronger and
stronger. It ended up being at Potters Point. I wish I checked the loop on the start
of this leg. It was now 11.30pm and time to get back to the room for a hard
Scottish drink. We were wrapped we finished and we weren’t the last team
either, although we would have finished at 10pm I think, if that loop was aligned. Poor Alayna was dead to the world.
 
Sunday
 
Event 4
This is a 10 leg ARDF event hunted on foot. Hmm, we tried but Mike and Alayna had issues with waking up after Saturday night’s effort. It started to drizzle too, and we didn’t like the idea of getting wet. So, off to the SERG hall for breakfast and bargain hunting instead.
 
Event 5
This was another Triple leg Hunt – another tough one. This hunt is fast, you need to change antennas fast, the first leg 70cm was straight north, driving past the airport to Telford Scrub Conservation Park. All the teams were very close.
 
The next leg was on 2m, but  none of us could hear it! Oh no, what now. We drove back out to the Riddoch Highway and headed north. The signal then finally comes up. Bugger its bearing is 9 o’clock, so we dive for the next main track to the left. We all follow each other and this fox is tricky. We find him but only after driving on both sides of his location to discover a track in-between. If we waited longer before we started this leg Kerry said we could have driven nearly straight to him saving many km.
 
The next leg was 70cm again. Kerry got a bit confused and we ended up following our Yagi for a while. This leg we got close and I did the rest on foot with the sniffer. We found it.
 
Event 6
This was another triple leg hunt, but this time with a twist. This hunt requires quick antenna changes again. 2m and 70cm we can do with a switch but the inclusion of 80m in this event means a manual antenna change to the loop antenna mid charge. The 80m loop is Rod VK5UDX’s and I’m not familiar with. Its not set up for my side of the car. 
 
Leg 1 – 2m fox was quite straightforward, we ended up behind a quarry on west side of the Mt Gambier forest, and it was so close half the teams were within seconds.
 
Leg 2 – 70cm this again was straight forward as we drive North West to a forest near Glencoe West.
 
Leg 3 – 80m this is when it got interesting, our in car 240volt power supply decided to put up noise on the fox frequency. It never does this normally! Each time I needed to stop for a bearing we had to kill the 240volts in the car. Because of this and the loop being very vague we drove around all over the place just trying to work out which direction the signal was. I got quite confused and Kerry could not get any clear direction of where to go. I tested the loop with my test signal and I found the car body was really affecting the pattern of the loop. In the end, we pulled out, as we had not much time to get to the next hunt. Bummer! Should have used my original loop that was back at the house.
 

Getting Ready for the 23cm hunt

Event 7

This is the 23cm hunt and is another favorite as the fox can do tricky stuff with reflections. They use a tin can radiator and can beam the signal to appear in totally different places. However, our Yagis are like a torch, nice and sharp and are great to DF with so we were in with a fighting chance.
The hunt started at the top car park near the caravan park on the lake. We headed off and I could not hear anything. I was on SSB 1296MHz, tuned down to 1295.996 and there was the fox very weak and fluttery. Not good as I didn’t get a decent direction, the next signal was a bit better and I determined the direction. Kerry got a line out of town possibly on the edge of the Myora forrest. We still didn’t not know how far it could be. We got to the round about near the show grounds and the bearing was not changing much. I determined with Kerry’s navigation the signal was far away. So we broke from the pack and head east to get into the 80km zone sooner. First left we headed north to get to Kerry’s bearing line. The signal stared to really pick up and getting much cleaner. We had a give way sign to deal with then a near straight run. What do we see, the hound pack leaders approaching the same intersection as us. We ended up having to
give way to them. A sharp right hand turn onto a track and there is the 23cm fox
lying in the tall grass out of sight. We got 4 th position. So close! And we were very
happy with this result.
 
Back to our rooms to clean up and relax then back to the SERG Hall for David’s WENET talk and fox hunt presentations. VK3FAST won the weekend again. SERG put on a great dinner again and we sat down with the VK3AI team. We had a great time talking about the action over the weekend. We even got tips on the next 80m loop design to try, I will try and build it for 2018.
 
The use of Google earth pro was invaluable. The old topo maps are so far out of
date and you need Google photos to get the real story. The GPS server soft
ware work flawlessly. Next year we may get another tablet PC and have both map
system running together. Two new GPS as the one I had stopped working on windows 10, long story ! Mike had to write some code and got his Auduino GPS bits going the day before Mt Gambier. Well-done Mike. The commodore did well and nothing broke this year. Alayna bottom still has feeling. Kerry wants a pencil holder and I want to make more room in the car. We also want to log our track with signal strength. Time to get coding!
 
We had lots of fun and did better than we thought. Alayna has plenty of things to talk about and I’m not sure if she had any wow moments. Only time will tell. This year we had plenty of people asking what we were doing and we explained its ham radio hobby looking for hidden transmitters.
 
Regards Adrian VK5ZBR

River Paddling Marathon 2017 – Community Safety Comms Event

The River Paddling Marathon 2017 has come and gone, and once again AREG in conjunction with the Riverland Radio Club and a number of interested radio amateurs who approached us asking to participate was successful in providing three radio networks covering 200km of the River Murray through the canyon country of South Australia’s Riverland district. There was a 2m voice network for canoe tracking traffic, a 2m APRS network for tracking the safety boat locations, and a VHF commercial network for the safety boats and medics.

The following report from Matthew VK5ZM, AREG President, sums up the weekend:

“I just wanted to say a big Thank you to all the volunteers that came and assisted us with the RPM again this year.  Without your support and assistance there is no way the AREG could assist with this event.

This year I saw flexibility and professionalism being displayed across the board as small hiccups occurred people came with solutions and simply got on with the jobs and tasks.  With this many willing hands a vast amount of difficult work got done in a very short time.

To the checkpoint operators my profound thanks.  For some of you getting out of bed between 4-5am, driving for up to an hour to sit by the banks of the Murray in chilly temperatures and watch the sunrise makes for a very long day.  I truly hope that our volunteers enjoyed themselves and had fun.  This year I’d also like to note that both Scott VK5TST and I observed our accuracy in reporting boat numbers was far higher this year, this made the job at the Bus significantly easier.

I’d also like to thank Sharon VK5FSAW, Irene, Colleen & Nonna for packing the lunches, preparing dinner on Saturday night, kicking Sharon out of her kitchen for a bit and keeping the troops fed and dishes done.  With 31 people on ground that is not an insignificant number of sandwiches, slice, cake and fruit to pack each day.  There will be much swapping of recipes this year I think…

Again I’d like to personally thank Peter VK5KX for the use of his Bus each day for net control, without the Bus and Peters preparation of the net control radio  systems the Comms team manning net control wouldn’t have anywhere near as much fun.  I know this year with the increased number of people at the Bus, Peter spent a much larger time running around making coffee and keeping people ticking over, for which I am personally thankful and likewise all that attended the Bus.

I’d also like to thank Grant VK5GR (and team: Andy VK5AKH, Kim VK5FJ, Darin VK5IX, Scott VK5TST, Mark VK5QI and Marcus VK5WTF) for piecing the radio network together.  This year was a challenge and seemed like a war of attrition at times as equipment hiccuped within the network.  However the network and tech teams kept the beast running, cracking the whip when required or threatening to send it to Darin VK5IX for a reprogramming/tuning it would never forget.  This year, at least, Darin frightened the Tait 2000s’ into submission, not a single one gave a problem out on the water, unlike previous years.

Another monumental task is checkpoint planning and notes preparation.  So a big thank you to Andrew VK5XFG and Kim VK5FJ for stepping up this year.  I know that your help reduced the workload on Grant and I significantly.  It takes a good week to just prepare and print the materials necessary.  I’m waiting on Andrew to tell me how many pencil sharpeners we got back this year.

Lastly I’d like to thank Scott VK5TST for his work at the Bus and on the software/database that we use to track the paddlers.  Scott has worked in the background on this software over the past year (ok last two months prior to event *grin*), taking suggestions from bus operators last year and tweaking the GUI/HMI to suit.   The improvements in efficiency was huge, I often amazed at how quickly he could come back with answers to common questions, closing of checkpoints and reconciling of paddler numbers when asked.  Entering the data was fast and painless, better yet it assisted operators with keeping within the procedure which was fantastic.

At the presentations on Monday afternoon the Race Director Martin Finn and all paddlers thanked the AREG (led) Comms Team for a job well done to the applause of the entire crowd.  I think the comms team this year should also pat themselves on the back for a job well done.”

AREG Next Meeting: Introducing LF and MF by Doc VK5BUG – 16th June

The next meeting of the Amateur Radio Experimenters Group Inc will be held on Friday June 16th, starting from 7.45pm at the Reedbeds Community Hall, Phelps Crt, Fulham.

The topic for this evening will be introducing LF and MF communications techniques, presented by David (Doc) Wescombe-Downs, VK5BUG. Doc is a pre-eminant authority on everything LF and MF in Australia, and is one of the modern pioneering amateur experimenters of these bands today. If you have ever wondered how on earth you can start using the 630 and 2200m bands from home, then come on down and hear Doc talk about whats possible.

Doc will also have a limited number of his books available to purchase for those taken with enough interest in the subject.

LowBand Book Promotion Flyer

After the presentation, there will be a short business meeting plus time to socialize and hear more about what happened at this year’s River Paddling Marathon (being run over the June long weekend and being supported by AREG and RRC).

You will find the clubrooms at the following address! We hope to see you there!

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.