Dayton Ham Convention 2019 17th to 19th of May

Hello from Eric KJ4YZI reporting from Dayton Ham fest with some interesting new Ham gear for us all. Attached a few new items that us hams might be interested in and were not able to make this Ham Fest.


Once again thanks to Eric KJ4YZI for his informative information and update on some new ham gear whats available hope you enjoyed just some of the highlights from this three day ham fest.

Cheers and 73’s Tom VK5NFT

Activities late April early May

The Heywood Rally will require us on Saturday 27th April only. It’s an early start at 7:00AM. Peter VK5BE is managing this event.

Communication will be via the Portable repeater which operates on the Willalooka frequency 147.350 (your receiver) and 147.950 (your transmitter). Peter and Colin will have checked out communications the week before (20/4/19) and it is expected that the repeater will cover the required area.

The repeater has a 1 second tail but no beep. It has a 10 minute timeout.

The repeater is running on two antennas – both folded dipoles with the receiver on top so it’s expected that a handheld should get in okay.

The Generations in Jazz event is on from 3,4,5 May. Andrew VK5KET is managing this event. Volunteer times to be advised.

The portable repeater is being placed approximately 1km from the Generations in Jazz site and will provide rock crushing signals to the area. Again the frequencies are 147.350 (listen) and 147.950 (transmit).

Well now you want to Setup a Hotspot ?

Well now you know all about D-Star, DMR, C4FM, Reflectors and talk groups and you want to go about setting up your own hotspot. So you to can be able to access these various talk groups with ease for yourself. Well please enjoy the following you-tube video once again presented by Eric KJ4YZI where he shows you what you need to get started and how configure the the device and get you on the air using it.

Thanks again to Eric KJ4YZI from HamRadioConcepts

Cheers and 73’s from Tom VK5NFT

DStar/DMR/C4FM, What Are Reflectors And Talkgroups

Ever wanted to know what they mean by a reflector?, What is a talkgroup?, Dstar or C4FM when it comes to Amateur Radio.
These words are always flying around, and a lot of people have no idea what they are. Hopefully in this video presentation it will help you to understand the very basics and explain to the terminology and how it all works. Hope you enjoy and get something out of this video.

Once again thanks to Eric KJ4YZI for his youtube presentation and explanation into DStar/DMR/C4FM, What Are Reflectors And Talkgroups

Cheers and 73’s from Tom VK5NFT

Amateur radio – a 21st Century hobby

Whether you enjoy writing software, getting hands-on with practical equipment, developing new technology or simply want to use what’s already there to communicate with others across the world, you’ll find all of this – and more – within amateur radio. It is also great fun.

21st Century Hobby for all

Why not try it, click onto to the link below to go to WIA and find a Amateur Radio Club under Radio Clubs and hopefully their is one near you.

Cheers and 73’s from Tom VK5NFT

Did I hear you say CB RADIO?

I started originally from the old days on 11 metres, known as the CB Radio Band, I know quite a lot of Amateurs of today started there too.  Well I found this video on the net and guess what, it’s all about CB Radios and probably a lot of us out there can relate to this video. Why did I put this on the listing to view, well anyone coming to our website and who doesn’t have a amateur licence could use this as a stepping stone into the hobby. I hope we can use this as an introduction from CB Radio towards Amateur Radio.

I hope you enjoy this video as there is some good reference material towards amateur radio.

If you are interested in getting a Amateur Radio Licence then click the link below:

Willalooka Repeater visit -17/2/19

On Sunday Tom VK5NFT, Alan VK5ZLT and I (VK5DJ) travelled to the Willalooka site. An 8:15AM departure was a bit much for DJ but he managed it. Tom drove and we arrived on site at 10:20AM. We were pleased to have a police escort for a little while – most appropriate for such an important visit.

The aim was to find the cause of the mixing product from 3WV, identify the changing signal strength on the Willalooka transmission and fix the noise that occasionally opens the Willalooka mute and propagates around the whole network. Not a bad list.

What did we find? Not much.

With the aid of his antenna analyser Tom checked the two repeater antennas, viz. the main one near the top of the tower and a temporary test antenna lower down. Both tested with an SWR of 1.2 at the TX frequency but about a MHz higher the SWR was 1:1. So the SWR favoured the RX rather than the TX. The sweep was broad so we decided that the antennas were near enough for government work.

One possible problem found was the antenna coax going into the cavities. It seemed to rotate within the plug. Further examination revealed threads of outer that may have been shorting out to the inner. Tom re-terminated the coax and tightened the nut, we felt much better about that. We checked all plugs for firm connections. Next John got out his DSA815 spectrum analyser/tracking generator and used it to sweep the cavities. The passband and notches checked out and when the cavities were reconnected to the TX and RX no receiver de-sense was evident. VK5ZAI at Kingston reported favourably on access.

Alan VK5ZLT and John VK5DJ discuss the cavity display

The repeater was re-assembled, connectors tightened and put on the original antenna. The mute was tightened a whisker to avoid noise opening the mute. It may be a little tight and cause chopping but better than noise holding up the network. We left the site about 1:30PM.

Tom VK5NFT and Alan VK5ZLT before closing up for the day

We thank Tony VK5ZAI for providing test signals during the day’s exercise. It makes a big difference having a distant station.

How to Tune a Band Pass Cavity using a DSA 815 Spectrum Analyzer

The above Youtube clip provided by Tom doesn’t apply to our cavities as ours are passband with a notch. Ours are more critical to tune, however it does give an idea about what is necessary for passband only.

Our cavities have a passband for the RX and TX but they also have a notch in their response 600kHz away. TX cavities have a notch on the RX frequency to remove transmitter noise, while receiver cavities have a notch in their response to remove the carrier. The video does show how to adjust the impedance match of the links and I haven’t done this in the past just adjusted the links for least loss. It might mean the same but in the short term I’ll practice this before next having to do this at a site. Never too young to learn.

Standing waves and SWR

At the meeting on 1/2/19 I described how we might use the club’s antenna analyser to best effect.

An important part of using the analyser is to understand the idea of standing waves.

I found this good illustration on youtube:

Hang in there, it’s a little slow moving but the illustration towards the end gives a really good visualisation of standing waves when there is a correct load and an open circuit.

How to tell if your SWR bridge is misleading you.
Have on hand an extension length of coax. It should be a ¼ wavelength long for the band you are experimenting with. After measuring your SWR, insert the extra length in the line – this moves your testing point 1/4 wave along the coax to a different point on the standing wave.

Here are some useful lengths:

6M band use a length of 1 metre, 2M band use 340 mm,70cm band use 13cm.

It’s not too critical. Now if your two SWR readings are similar (e.g. 1.2 and 1.3 then you probably don’t have a big problem but 1.2 and 2 would be unacceptable and require more investigation.

To actually calculate the length of the 1/4 wave section the formula is:
75*0.67/freq in MHz and the answer is in metres.

e.g. for 2M it’s 75*0.67/144.0 = 0.348 metres

I’ve used 0.67 as the velocity factor, this is true for many coax cables. Heliax is more likely to be 0.8.

John VK5DJ

Chasing Weather Balloons

Recently a number of South East Radio Group members have been tracking weather balloons here in South East South Australia.

A balloon is released automatically from the Mount Gambier Airport each Monday and Thursday morning at 10.45 a.m. local time and if some unusual weather conditions are expected, at any time.

We watch the predicted flight path on Hab Hub Predictor and then track the actual flight path on Hab Hub Tracker. Sometimes the two plots agree and others not very well.

The prediction for yesterdays balloon originally had it landing somewhere near Hamilton but this was revised to a spot just East of Strathdownie in Victoria.

Charles, VK5HD rang me at about 11 a.m. and asked if I was going to chase it or if I might be interested in doing so. As it was not going to be very far from the Mount I suggested that I ring Tom, VK5EE, and invite him as well. Charles agreed and Tom and I met up with him at his home in Mt. Gambier at 1 p.m. and off we went.

After crossing the border on the way to Casterton we turned right onto West Strathdownie Road and then turned right onto McGrath’s Road. We travelled along McGrath’s Road for a short time until our GPS indicated that we were getting close to the landing area.

Charles had his hand held on and tuned to 401.500 Mhz. and right on cue we started to hear the signals from the Sonde. It had landed pretty much exactly where the tracker had placed it. We turn off McGraths road and drove a few hundred metres up along the Western edge of a stand of pine trees and parked.

After climbing over the fence into the paddock Charles thought he could see the Sonde but it turned out to be the wool from a sheep carcass.

Col, VK5HCF thought that he saw it just a bit to the North and so we changed direction and carried on walking. Bingo. There was the Balloon, (in tatters of course), and the parachute. Col traced the flimsy line from the tangled mess of the Balloon back to the actual sonde. The line was surprisingly long, maybe 30 metres or so.

All good. Charles coiled the whole mess up and we carried it all back to the car pretty happy with such an easy recovery.

We were only away for about an hour or so which meant minimal disruption to our day.