SOTA – 23 and 13cm from Mt Coree

Sunday 20 January 2019. Mt Coree (QF44JQ) 1421 metres ASL, Namadgi National Park, Australian Capital Territory

GPS track route is available here

“272 km via an A380 aircraft enhancement reflection en route to Sydney”

Mt Coree at 1421 metres ASL is a premier location for VHF-UHF Dx operations. Mt Coree dominates the Brindabella Ranges with it’s impressive granite structure with sheer vertical cliffs. The 360 degree view is commanding and for VHF-UHF radio purposes there are no vertical obstructions to the horizon. The summit is perfect for long distance (Dx) VHF-UHF-Microwave radio contacts out to VK2 and VK3.

Tony VK1VIC and I are undertaking a SOTA activation of Mt Coree. Tony is operating on 14 and 7 MHz and is very keen to qualify using CW mode. To qualify a SOTA summit the activator must complete valid signal report exchanges with a minimum of four unique callsigns. There is no upper limit to the number of stations worked on a SOTA summit, however for practical or safety reasons the activator has the choice to terminate the activation when deemed necessary.

VK1AD SOTA shack at Mt Ginini, Namadgi National Park

Equipment at the summit

  • SG-Lab 23 and 13cm transverters
  • FT-817ND
  • 13 volt 4S 8.4 Ah LiFePO4 battery
  • 2m/70cm dual band yagi
  • 23cm 1296 MHz Bi-Quad antenna
  • 13cm 2.4 GHz Bi-Quad antenna
  • 70cm 433 MHz flower pot antenna
  • 2 x 1.4 metre tripods
  • Lenovo 7 inch tablet
  • Flightradar24 software
  • Compass
  • Backpack, food, water, first aid kit

2m/70cm Dual Band Yagi & 23cm Bi-Quad at Mt Coree

View east to Canberra, cloud covering the summit


Cloud descends on the summit

View west over Brindabella National Park


Hombrew 13cm Bi-Quad antenna

View south-west


Homebrew 23cm Bi-Quad antenna – working VK2FLR at 272 km north-east

Extract of VK1AD SOTA Activator Log: 19 January 2019 – Mt Coree

Six unique QSOs on 1296 MHz and 2.4 GHz and seven QSOs on 144 MHz

Summit to Summit QSOs: Jim VK1AT Mt Stromlo VK1/AC-043 (QF44MQ)

Best DX long distance QSO on 23cm (1296 MHz) at 2.5 watts using the Bi-Quad antenna was with Mike VK2FLR in Sydney. The over-the-horizon path is 272 km via an A380 aircraft enhancement reflection en route to Sydney. 🙂

Time Call Band Mode Notes
22:19z VK1JA 144MHz SSB QF44NO Jason s59 r59
22:21z VK1MT 144MHz SSB QF44NM Matt s59 r59
22:22z VK1MCW 144MHz SSB QF44NN Bill s59 r59
22:25z VK1AT/P 144MHz SSB Jim s59 r59 S2S VK1/AC-043
22:32z VK1RX 144MHz SSB Al s59 r59
22:35z VK1DSH 144MHz SSB Dale s59 r59
22:38z VK1DSH 1296MHz SSB QF44MS Dale s58 r55
22:39z VK1MT 1296MHz SSB QF44NM Matt s58 r58
22:40z VK1RX 1296MHz SSB QF44NN Al s58 r59
22:41z VK1JA 1296MHz SSB QF44NO Jason s59 r59
22:44z VK1MCW 1296MHz SSB QF44NN Bill s59 r59
22:50z VK1AT/P 2.4GHz SSB QF44MQ Jim s56 r59 S2S VK1/AC-043
22:52z VK1MCW 2.4GHz SSB QF44NN Bill s59 r59
22:53z VK1DSH 2.4GHz SSB QF44MS Dale s51 r54
22:56z VK2YK 146MHz FM Adam s59 r59
23:02z VK1JA 2.4GHz SSB QF44NO Jason s59 r59
23:03z VK1RX 2.4GHz SSB QF44NN Al s58 r59
23:09z VK1KW 2.4GHz SSB QF44MT Rob s58 r55
00:11z VK2FLR 1296MHz SSB QF56OD Mike s55 r51 272 km

Photos: © Copyright 2019 Andrew VK1AD


SOTA – VK1 1.2 and 2.4 GHz from Booroomba Rocks 1382 m ASL

Sunday 1 July 2018 – SOTA activation of Booroomba Rocks 1382 metres (4537 ft) ASL, Namadgi National Park on 23 and 13cm (1296 and 2403 MHz)

To secure four unique callsigns on 23 and 13 cm, one needs to plan ahead by informing interested parties at least 2 days out, well that’s the story in VK1. It’s just as much fun organising chasers as it is hiking up the mountain. 🙂 I’m taking advantage of the well-known VK1 VHF Dx Net group who are on air from 0800h to 0900h local (2200 to 2300 UTC). For me and my plans to activate Booroomba Rocks it means a very early start at the base of Booroomba Rocks in the dark, it’s winter in this region of eastern Australia. The 240 metre vertical ascent over 2.2 km takes about 1 hour, I made the summit by 0730h local with 30 minutes up my sleeve to set up.

Looking south to Booroomba Rocks highest point. That’s my target, time is currently 7 am and the weather is looking good. I have just spent 40 minutes climbing in the dark with a headlamp. The summit is a further 20 minutes away.

Great view of the Moon

Sun just peeking over the horizon – I’m now at 1300 m ASL

At the summit and this is the view north to Canberra which is now under the clouds

90 minutes later

Rock Pools are solid blocks of ice, overnight temperature was minus 5 degrees C

VK1AD SOTA shack at the summit

Equipment carried to the summit

Yaesu FT-817 for 2m and as the IF for SG-LAB 23 and 13 cm transverters.

Extract of VK1AD SOTA Activator Log: 30 June 2018 UTC Booroomba Rocks

UTC Callsign Band Mode Distance (km) Grid Square / Notes
22:28 VK1DSH 2.3GHz SSB 37 QF44MS DALE S59 R59
22:30 VK2COW/P 2.3GHz SSB 63 QF44OX DIMITRI S59 R59
22:32 VK1RX/P 2.3GHz SSB 19 QF44NN AL S58 R57
22:33 VK1KW 2.3GHz SSB 42 QF44MT ROB S59 R59
22:46 VK1KW 1240MHz SSB 42 QF44MT ROB S59 R59
22:47 VK1MT 1240MHz SSB 15 QF44NM MATT S59 R59
22:48 VK1DSH 1240MHz SSB 37 QF44MS DALE S59 R58
22:50 VK1RX/P 1240MHz SSB 19 QF44NN AL S59 R59
23:19 VK1AT/P 1240MHz SSB 28 QF44MQ JIM S59 R59 S2S VK1/AC-040
23:27 VK1MCW/P 1240MHz SSB 15 QF44NM BILL S59 R59 S2S VK1/AC-03

As you can see from my log extract, I qualified with a minimum of four unique callsigns on each band 23 cm (1296 MHz) and 13 cm (2.4 GHz). Furthest contact on 2.4 GHz was with Dimitri VK2COW at 63 km (39.1 miles), signal reports were excellent.

Summit to Summit (S2S) QSOs included Jim VK1AT at Mt Ainslie and Bill VK1MCW at Bullen Range.

4el 2m yagi, SG-Lab 23 cm transverter and an all brass 6el 23 cm yagi

SG-Lab 13cm transverter and a 13 cm Bi-Quad antenna

Photos: © Copyright 2018 Andrew VK1AD

SOTA – 23cm from Mt Coree

VK1AD SOTA shack at Mt Coree VK1/AC-023 @ 1421 metres ASL, Namadgi National Park VKFF-0377, Grid QF44JQ

Australia’s Capital Territory (ACT) is experiencing 4 days of heatwave conditions with daytime temperatures up to 39 degrees C (102 F). To take a break from the early morning heat my wife and I headed for the summit of Mt Coree where the ambient temperature is 10 degrees cooler than the landscape below.

In the picture below, an early morning (7:30 am) inversion layer has trapped smoke from bushfires north of Braidwood in NSW.

Photos: © Copyright 2018 Andrew VK1AD

view east – Inversion layer trapping smoke from nearby brushfires. Today’s top temperature is 39C.

In close the fire watch tower, on the horizon a view north over a blanket of cloud. The summit is 1421 m above seal level

View west – Brindabella National Park. To the right of the picture is Dingi Dingi Ridge VK2/ST-004 and Webbs Ridge VK2/ST-005

Extract of VK1AD SOTA Activator Log: 20 November 2017 Mt Coree

Today’s QSO of the day on 23 cm (1296.150 MHz) was with Michael VK2FLR in Sydney Grid (QF56OD). The 23cm signal path is 272 km, my antenna is a homebrew 12el yagi.

On 23 cm I did hear Trevor VK3VG confirming a QSO with Rob VK1KW. I called Trevor two or three times without luck. Distance to Trevor’s location QF42UK from Mt Coree is 263 km.

Bands worked 2m, 6m and 23cm.

Time Call Band Mode Notes
21:24z VK1AI 144MHz SSB Greg s58 r55 144.2
21:27z VK1DJA 144MHz SSB Dave s59 r58 144.2
21:30z VK2UH 1240MHz SSB %QRA%QF45LD% Andrew s58 r56 49 km 1296
21:32z VK1KW 144MHz SSB Rob s59 r59 144.2
21:33z VK1MT 144MHz SSB Matt s59 r57 144.2
21:34z VK1BG 144MHz SSB Ian s59 r59 144.2
21:35z VK1RX 144MHz SSB Al s59 r59 144.2
21:36z VK1FWBD 144MHz SSB Wade s59 r59 144.2
21:38z VK1KW 1240MHz SSB %QRA%QF44MT% Rob s59 r59 20 km 1296
21:39z VK1MT 1240MHz SSB %QRA%QF44NM% Matt s58 r58 33 km 1296
21:43z VK1BG 1240MHz SSB %QRA%QF44MS% Ian s59 r59 18 km 1296
21:52z VK2FLR 1240MHz SSB %QRA%QF56OD% Michael s51 r31 268 km 1296
22:09z VK1CT 144MHz FM Chris s59 r57 146.5
22:13z VK1RX 50MHz SSB Al s59 r59 50.160
22:16z VK1CT 144MHz SSB Chris s58 r59 144.2
22:21z VK1DI 144MHz SSB Ian s59 r59 144.2
22:37z VK1RZ 50MHz SSB Roald s59 r59 50.160
22:44z VK1MA 50MHz SSB Matt s59 r59 50.160
22:48z VK1WX 50MHz SSB Amanda s59 r59 50.160

VK1AD SOTA shack at Mt Coree VK1/AC-023 at 1421 metres ASL

3el 2m yagi and a 23cm Bi-Quad

Mt Coree Trig Station. The telescopic pole is supporting a 6m 1/2 wave coaxial dipole

23cm Transverter – Tripod Platform and Bi-Quad Antenna Mount

At VK1AD Bi-Quad antenna construction I’ve had a hoot-of-a-time building 23cm antennas for SOTA and portable field ops. 🙂

“It’s time to cut my signal losses..”

For sometime I have used a 1 metre length of LMR195 coax feed line between the 2.5 watt 23cm transverter and my choice of antennas. Due to the feed line length this option introduces losses in both transmit and receive signals. Weak or marginal 23cm received signals are attenuated by feed line losses. In the picture below you can clearly see the feed line length, yes you are right it’s too long! (Mt Gillamatong 19 Nov 17)

VK1AD SOTA shack at Mt Gillamatong 19 Nov 17

It’s time to cut my signal ‘losses’ and move the transverter to the top of the tripod. This option permits the full extension of the tripod to a height of 1.4 metres above ground level, every millimetre gained helps.

Sunday 31 December 2017…its New Years Eve and I have nothing on my plate!  Starting with a tripod mount for the 23cm Bi-Quad antenna, also known as a double-quad antenna, I have also spent the afternoon fabricating a small platform for my SG-Lab 23cm transverter.

First let’s look at the the Bi-Quad antenna mount

Camera top plate – I purchased two standard top plates on eBay. Remove the 1/4 inch screw from the center of the plate.

Tripod head – top plate receptor in the vertical position

Mount the spare top plate to the rear of the 23cm Bi-Quad antenna. Do you like my nifty teeny-tiny G clamp?

rear surface of the Bi-Quad antenna

outline of the top plate

Top plate secure at the rear of the Bi-Quad by two 3 mm screws, washers and nuts

top plate secured to the rear surface area

Bi-Quad antenna fitted to the tripod head – it’s a neat fit.

Construction of a Transverter Platform

In the picture below you can see the tripod head locking knob has space behind the knob flange – Let’s be clever and make use of the space behind the knob and the flat surface of the head. 🙂


Homebrew double-sided copper clad PCB platform – I love fabricating stuff, useful or otherwise! You are not restricted to using double-sided PCB, you may have other materials on hand such as sheet aluminium. Go ahead explore the junk box.

Transverter platform secured by the tripod head locking knob – cool 😉

23cm Transverter and 6el Yagi antenna – LMR195 feed line is now 50% shorter at 500 mm

23cm Transverter and Bi-Quad antenna – For now ignore the feed line length, I will make up a 200 length of RG58 Cell Foil.

That’s my ‘New Years Eve’ afternoon of fun playing amateur radio antenna construction! I will test the B-Quad tomorrow from South Black Range, 40 km south-east of Canberra.

Post update: 6 February 2018

Construction and assembly of a new 200 mm feedline between the transverter RF output socket and the Bi-Quad antenna socket.


200 mm length of 50 ohm ‘Cell Foil’ terminated in male sma connectors

23cm transverter – 200 mm 50 ohm RG58 Cell Foil feedline

You have my permission to copy the design and build your own.  😉

Happy New Year to all and have a safe time playing SOTA in 2018 🙂

73, Andrew VK1AD

Published: 31 December 2017
Last Update: 12 March 2018