AREG’s HF Spectrograph shows the effects of Solar Flares

An X-class Solar Flare imaged by the Solar Dynamics Observatory in 2012.

An X-class Solar Flare imaged by the Solar Dynamics Observatory in 2012.

Solar flares from the sun can result in many different effects on High Frequency (HF) propagation. The most immediate and noticeable is when the increased solar X-Ray flux resulting from a flare interacts with the ionosphere. These X-Rays charge the ionosphere’s D-layer (responsible of the absorption of the lower HF band during the daytime), and results in higher levels of absorption extending right up to the top of the band. This has the effect of reducing signal strengths right across the band, resulting in what is known as a ‘HF fadeout’.

X-Ray Flux data from the GOES satellites, provided by NOAA

Solar flares are categorised based on the peak X-ray flux they emit, with the different levels given letters A, B and C for relatively weak flares, and M and X for stronger flares, with X-class flares being the strongest. HF fadeouts are generally caused by M and X-class flares. A live plot of X-Ray flux data as observed by the Geostationary Operational Environment Satellites (GOES) is available here:

Short Wave Frequency Coverage Prediction

HF Fadeout Coverage area for a M1.2 class flare, from the Space Weather Service website.

The Australian Space Weather Service provides a HF fadeout warning service via email, and you can also see reports of the most recent HF fadeout on their website.

AREG’s HF Spectrograph Service

AREG hosts many services at its remote HF receive site located near Tarlee, including multiple KiwiSDRs, skimmers for WSPR, FT8 and SSTV, and other higher performing receivers reserved for club members. We thank Swoop Internet for providing us with the internet service at this site, for free!

The HF receiver antenna (a broadband monopole) at AREG’s remote HF receive site.

Using software written by Mark VK5QI, AREG also generates a Spectrograph showing the state of the HF band over the last 3 days. A spectrograph is similar to the waterfall display you might have seen on other SDR receiver software, though in this case covering the entire HF band (0 – 30 MHz), and looking over a much longer timescale. Warmer colours (reds and yellows) represent stronger signals, and cooler colours (blues and greens) represent weaker ones. The spectrograph updates approximately every 30 minutes, and is available at the bottom of the Remote HF Receiver site page, or directly here.

A typical HF Spectrograph, with some features annotated.

The spectrograph gives us a ‘quick look’ at the state of the HF band. The strongest signals (red) are the bands of shortwave stations around 6, 7, 9 and 11 MHz, mostly propagating in from south-east Asia. The most obvious time-varying effect is the change in propagation conditions from day (propagation mainly at the higher end of the band), to night (propagation mainly at the lower end of the band), but we can also see other effects such as solar radio bursts, local noise issues, and of course HF fadeouts.

In the above figure, a number of HF fadeout events over the 18th through 20th May 2023 period have been marked, showing the X-Ray flux event they correspond to. The HF fadeouts can be seen as a sudden reduction in signal strength right across the HF band, followed by a slow return to normal. Note that we don’t see the effects of X-ray flux events occurring during our local night, due to the Earth sheltering us from those X-rays.

So, next time you think the HF band seems a bit dead, maybe go take a look at the AREG HF Spectrograph to see if there’s a HF fadeout in progress!

73 Mark VK5QI

AREG’s VK5RSA Adelaide CBD repeater – supported by KernWi-Fi

One of the services that the Amateur Radio Experimenter’s Group provides is a network of repeater stations that cover the Adelaide metropolitan and surrounding areas. These systems operate on the 6m-23cm bands from 3 sites in and around Adelaide.

One of the first repeaters conceived by AREG was the Adelaide CBD repeater. Inspired in the 1990s by the original 438.025 VK3RCC repeater in Melbourne (which was located atop one of the hi-rise towers in Melbourne CBD), the intention was to reach the deep CBD buildings and the Adelaide foot hills shadowed by the existing repeaters atop the Mt Lofty ranges.

The AREG repeater in Adelaide was originally established on top of the original Angas Street police station building – then 11 stories high in Victoria Square. When that building was subsequently demolished, it was moved to another building off Flinders Street, where it ran for many years before finally developing a terminal fault.

Today, VK5RSA is back on what now is one of the best communications sites in the CBD. This is all thanks to the support AREG receives from KernWi-Fi, who are sponsoring access to Westpac House on King William Street in the heart of the Adelaide CBD.

VK5RSA operates on 438.025MHz TX -7.0MHz RX with 91.5Hz CTCSS

The repeater also received a major coverage boost when it was restored,  as we were able to connect it to the new central SA repeater network. This enhanced coverage for hand held users deep within the Adelaide CBD and extended it right across across central SA to places as far afield as Pt Wakefield, Yorke Peninsula, Victor Harbor and east as far as Tintinara.

AREG offers it’s sincere thanks to Phil Kern at KernWi-Fi for his support for the project to re-establish VK5RSA – it is fantastic to have been able to restore this service for the amateur radio community in Adelaide – and from such a fantastic site too!

About our Sponsor

KernWi-Fi supply FibreNBN, Fixed Wireless Internet, VoIP, Event Wi-Fi and Radio Communications to residential and businesses all over Adelaide.  They also specialise in servicing the black spots of Adelaide.  To learn more, visit their website!

They are 100% Adelaide based and owned Licensed Carrier and work with many local communities to provide high speed internet services. They also sponsor various community groups across the state.

VK5 WIA QSL Bureau News – April 2021

6+ kg of cards sorted waiting distribution

AREG is pleased to announce that the next load of cards has arrived from the WIA National Inwards QSL bureau and is in the process of being sorted. Over 6 kg of cards are waiting sorting in the bureau at this time.

Over the next 2-3 months opportunities to collect cards will be made available at the North East Radio Club Buy’N’Sell in Adelaide on Saturday April 17th, as well as at the AREG General Meeting Friday June 18th.

WIA members will have their cards posted to them by the end of June as their yearly card mail-out. Should you want your cards sooner, please email: and we can see what arrangements can be made.

Members of affiliated clubs will start to receive their cards in early July through their local radio club. Non members will need to contact Grant VK5GR at the VK5 inwards QSL Bureau and make arrangements to send a self addressed and stamped envelope or mail bag (check beforehand as some people have LOTS of cards waiting).

Cards will be stored for 12 months before being disposed of so if you are not a member of the WIA or an affiliated club, you need to make arrangements to either collect in person or send a mailbag for return postage.

Adelaide CBD 70cm Repeater returns to service! (UPDATE)

After several years off air and/or operating from a temporary site in the western suburbs, the Amateur Radio Experimenter’s Group is please to announce that we have been able to negotiate a new home for the club’s VK5RSA Adelaide CBD 70cm repeater!

AREG has entered into a sponsorship agreement with KernWi-Fi, who are supporting the club by facilitating access to one of the premier communications sites in the Adelaide CBD atop Westpac House. At 134m high, this site is on one of the highest buildings in the city! AREG wishes to express it’s sincere thanks to Phil Kern (VK5ZEY) for his support of the VK5RSA repeater. It has been a dream of the club to gain access to the site for nearly 20 years and it is great to see it finally come to fruition.

The repeater itself has been rebuilt by Paul VK5BX & Dean VK5HMV, and was installed by Dean VK5HMV and Shane VK5NRV over this past weekend. This was the culmination of 9 months of discussions and planning by the AREG Committee, members on the repeater sub-group and the KernWi-Fi team.


VK5RSA operates on

438.025MHz (-7MHz input)

with 91.5Hz  CTCSS


NOTE: The repeater input frequency was changed Monday night due to un-resolvable interference from the co-sited commercial operators. VK5RSA is now operating according to the new 70cm band plan, with a repeater receive frequency of 431.025MHz. This is a -7MHz offset instead of the old -5MHz offset that was in use previously.

But Wait – there’s more!

In addition to being installed atop one of the highest buildings in Adelaide, VK5RSA is now part of something much bigger. It has now joined the growing Central South Australian repeater network, which provides coverage over most of central SA.

The repeaters in the network are:

Location / AreaCallsignOutputInputCTCSS
Adelaide CBDVK5RSA438.025MHz-7MHz91.5Hz
Adelaide RegionVK5RAD439.925MHz-5MHz
Adelaide NEVK5RKW438.050MHz-7MHz
Lobethal / Adelaide HillsVK5RAH146.775MHz-600kHz
Mt Bevor / Murray BridgeVK5RMB146.875MHz-600kHz
Victor HarborVK5RVH147.100MHz-1.6MHz

NOTE: With the network access comes a change in mind set for operators too. For all 6 repeaters to operate together, it is important for users to leave at least a 1 second gap after the repeater tails before transmitting. This will give sufficient time so that all of the transmitters and receivers can sequence correctly thus preventing one or more repeaters from being locked out.

The nominal best areas to access each repeater are shown here:

Strongest Serving Repeater Map (Note Victor Harbor not shown)

The coverage of the system is expected to be second to none in this part of the state. AREG hopes by making VK5RSA part of this network that it will help bring amateurs together on VHF/UHF and will drive new activity on these bands!

We look forward to hearing you on VK5RSA and the link network! Come and give it a go….

AREG Remote HF Receive Site – Now Open to the Public

AREG is pleased to announce that we can finally open ports on our HF Remote receive site to the general public.

The AREG HF receive site, located ~100km north of Adelaide, in South Australia, is now operating a publicly accessible KiwiSDR 4 channel receiver. This is the first active public service that the club is offering from the site. The system is currently using a broadband mono-pole vertical antenna.

AREG members also have access to much, much more, including dedicated members only KiwiSDR receiver channels, band by band high performance SDRs (Airspy HF+ Discovery, via SpyServer) on 160-20m, APRS-IS HF RX gateways and Weather Stations. If you are interested in joining the club to experiment with these other services, please (click here).

The site, which has been in development now for approximately a year, has other member services planned into 2021. Stay tuned as we continue to experiment and expand our capabilities at the site, including potential Reverse Beacon nodes, FT8 skimmers, WSPR skimmers and VHF monitoring services.

How to Access the Public KiwiSDR?
You can access the public service from the following web address:

Thanks Beam Internet!

AREG wouldn’t have been able to make this possible without the support of Sam from Beam Internet, who have sponsored our internet feed at the site.

Beam provide wireless internet connectivity to communities right across the Barossa Valley and northern Adelaide Plains.

Thanks team for your support of experimental Amateur Radio!

Using the KiwiSDR
For first time KiwiSDR users the following notes should be considered

  • Windows: Firefox, Chrome & Edge work; IE does not work.
  • Mac & Linux: Safari, Firefox, Chrome & Opera should work fine.
  • Open and close the panels by using the circled arrows at the top right corner.
  • You can click and/or drag almost anywhere on the page to change settings.
  • Enter a numeric frequency in the box marked “kHz” at right.
  • Or use the “select band” menu to jump to a pre-defined band.
  • Use the zoom icons to control the waterfall span.
  • Tune by clicking on the waterfall, spectrum or the cyan/red-colored station labels.
  • Ctrl-shift or alt-shift click in the waterfall to lookup frequency in online databases.
  • Control or option/alt click to page spectrum down and up in frequency.
  • Adjust the “WF min” slider for best waterfall colors.

WIA VK5 QSL Bureau Sort underway for 2020

The yearly WIA VK5 QSL Bureau sort for 2020 is now underway. Considering the reduced opportunities to meet in person, this sort will be followed by the once a year mail-out to WIA members of their cards (as included in your WIA membership). It is hoped to send all current VK5 WIA members your QSL cards in the next 4 weeks.

Non-members who are members of a WIA affiliated club should make sure their details have been passed to the VK5 QSL Bureau Manager, Grant VK5GR, via your club secretary so that your cards can be included in the mailing to your club.

If you are not a member of the WIA or an affiliated club, but still want to receive your cards, please email to make suitable arrangements. Cards can be collected in person by arrangement, or can be mailed if a self addressed pre-paid satchel is provided. If you wish to inquire as to whether you have cards waiting you can also contact us at the above address.

Operation of the VK5 WIA Inwards QSL Bureau is carried out on behalf of the WIA by the Amateur Radio Experimenters Group Inc!

If you wish to send outbound cards via the WIA bureau and are a member of the WIA please use the national Outwards bureau address:

WIA Outwards QSL Bureau
PO Box 66
Boolaroo NSW 2284

WIA VK5 Inwards QSL Bureau – New Operational Details Announced!

The Amateur Radio Experimenters Group is wia-logo-image_1_hirespleased to announce that it has finalized the new arrangements for the WIA VK5 inwards QSL bureau. Grant VK5GR is the current volunteer VK5 bureau manager from AREG. The club will be following the existing WIA QSL policy and will continue to encourage all amateurs that use the QSL Bureau to join the WIA.


Specifically, the arrangements will be:

Outgoing QSL BureauAustralia_Post_box-small

  • All outgoing WIA member QSL cards are to be sent to the national outgoing QSL address (the AREG will not be handling outbound cards):
    WIA Outwards QSL Bureau
    P.O. Box 66
    NSW 2284

Incoming QSL Cards to the VK5 Bureau

  • Incoming cards for WIA members are to be sent to the national incoming QSL address (not the AREG PO Box as previously advised by the WIA)
    National Inwards QSL Bureau
    P.O. Box 2040
    Bayswater Vic
    3153 Australia

Information for VK5 WIA Members

  • VK5 WIA members will continue to receive cards in the mail once a year to their registered WIA membership address. To update this address, please contact the WIA National Office
  • VK5 WIA members can nominate an affiliated WIA club to receive their cards for distribution on their behalf. This will likely increase the frequency that cards will be distributed.
  • VK5 WIA members can also arrange an off cycle collection of their cards at an AREG club meeting by prior arrangement (please give at least two to three weeks notice so that we can ensure that your cards are at the meeting for collection). Email if you wish to pick up your cards at an AREG meeting this way

Information for WIA Affiliated Club members

If you are not a WIA member but you are a member of an affiliated WIA club in VK5, you can still receive your QSL cards via your club secretary.

The individual club secretaries are responsible for keeping the VK5 QSL Bureau manager up to date with your club membership status. Every time a club mail out is planned, the bureau manager will check with the secretary for their latest membership lists.

Information for non-members

Non members of the WIA or an affiliated club who have QSL cards arrive here at the bureau need to make sure they are collected at least once per year, or they will be destroyed. Once a year, cards will be taken to an AREG meeting in Adelaide for non-members to visit and collect them. Cards will also be made available at the yearly AHARS Buy’n’Sell event.

If non members wish to have their cards posted to them, they must forward a self addressed pre-paid 5kg mailing satchel or if there are less than 20 cards in the bureau, they must send a self addressed heavy letter stamped ($3.30 at time of writing)  envelope. No other form of non-member collection is accepted by the VK5 bureau. Email the bureau manager first to confirm the volume of cards to be collected.

Ideally, non-members are encouraged to become members of the WIA to help cover the cost of their incoming use of the QSL bureau.


Andrew VK5XFG, Sharon VK5FSAW, Gary VK5FGRY and Andy VK5AKH sorting cards with Chris VK5CP and Grant VK5GR


AREG to manage VK5 QSL Bureau

QSL cards come in to the VK5 QSL Manager from the WIA National QSL Bureau around every 3 months. Upon arrival, they require some sorting and then forwarding out to the various VK5 clubs. Stephan VK5RZ has been admirably performing this role for a number of years. He has, however, had to resign from the position due to commitments he has with study. AREG commends Stephan on the effort he has put into the bureau and wishes to express our appreciation for the work he has put into the role.

AREG Accepts the Challenge!

The members of AREG, many of whom have an active interest in HF DX operating and QSL cards, decided that this was a function that the club ought to take on as a service to the VK5 amateur radio community. As a result of a motion at the last AREG general meeting, AREG has indicated it’s willingness to accept the task to the WIA board.

Please note: as soon as the administrative tasks are completed to effect the transfer, new details for the bureau will be announced here and in all relevant amateur media. Until then, please hold off making inquiries as we are not yet in a position to respond.

AREG QSL Gallery

As VK5ARG itself gathers more cards, the club is maintaining a QSL gallery of cards it has received on it’s website for members to see the results of their  handywork! Why not go and check out the AREG QSL Gallery while you are here?