23cm on 23rd #2 – 23 March 2019

Saturday 23 March 2019. I have organised a VK1 SOTA ’23 on 23′ event where SOTA tragics, that’s like minded SOTA activators, have the opportunity to join others for a local Summit to Summit (S2S) fest on 23cm 1296 MHz, SSB, CW and FM modes.

Today’s SOTA activators include:

  • Compton VK2HRX/P at Mt Gibraltar 163 km north-east
  • Jim VK1AT/2 at Mt Cowangerong 43 km east
  • Andrew VK1DA/P at Mt Mundoonen – 70 km north
  • Al VK1RX/2 at Spring Range – 40 km north
  • Bill VK1MCW at Mt Stromlo – 17 km north
  • Chris VK1CT at Mt Majura – 24 km north-east

Our local VK1 23cm enthusiastic chaser group is just as impressive which includes: Rob VK1KW, Jason VK1JA, Ian VK1BG, Matt VK1MT, Chris VK1DO/VK2DO, Rod VK2TWR, Dale VK1DSH and the occasional contact with Dimitris VK2COW. In Sydney 276 km north-east Mike VK2FLR and Compton VK2HRX take an interest in the hunt for 23cm signals emanating from VK1.

Today my plan is to activate Tuggeranong Hill VK1/AC-038, 855m ASL in grid square QF44NN. I left home at 6:30 am, yep it’s dark outside, for a 20 minute drive to Callister Crescent, Theodore at the base of Tuggeranong Hill. From the car park the walk to the summit takes 30 to 35 minutes to cover 1.5 km along a fairly steep gravel fire trail. See below screen shots.

Tuggeranong Hill GPS Track Log

Tuggeranong Hill GPS Track Log

Tuggeranong Hill track Profile

Tuggeranong Hill track Profile


Sunrise 7 am local

23cm equipment:

To drive a 23cm transverter one needs an IF source, conveniently SG-Lab’s 23cm transverter is designed to operate with a 144 MHz IF input between 0.5 to 5 watts all mode. What is the most common portable QRP SOTA rig around and ideal to work as a low power IF on 2m and 70cm, yep the Yaesu FT817! The rear SO239 antenna port is driving the 2m yagi while the front BNC port is driving the 23cm transverter.

You can of course drive the 23cm transverter with a 2m HT operating on FM, as I did last month from the summit of Mt Taylor.

Map courtesy of SOTA Maps. Furthest contact is Compton VK2HRX at Mt Gibraltar VK2/IL-001 162 km north-east, next is Rod VK2TWR 120 km south at Nimmitabel.

VK1AD 23cm QSO 20190322

VK1AD 23cm QSO around VK1 20190322

Extract of VK1AD SOTA Activator Log: 22 March 2019 UTC (23 March 2019 local) – Tuggeranong Hill QF44NN

Time Call Band Mode Notes
20:41z VK1FXNZ 144.2MHz SSB QF44NT John s59 r59
20:45z VK1JA 144.2MHz SSB QF44NO Jason s59 r59
20:46z VK1DO 144.2MHz SSB QF44PO s59 r59
20:47z VK2HRX/P 144.2MHz SSB Compton s34 r34 S2S 162 km
20:49z VK1DO 1296MHz SSB QF44PO Chris s59 r59 18 km
20:50z VK1AI 144.2MHz SSB QF44MP Greg s59 r59
20:51z VK1KW 144.2MHz SSB QF44MT s59 r59
20:53z VK1KW 1296MHz SSB QF44MT s59 r59 30 km
20:54z VK1JA 1296MHz SSB QF44NO Jason s59 r59 4 km
20:58z VK1DSH 1296MHz SSB QF44M Dale s58 r59 26 km
21:01z VK2TWR 1296MHz SSB QF43PL Rod s55 r55 120 km
21:04z VK1AT/2 1296MHz SSB QF44IS Jim s56 r58 S2S VK2/ST-001 43 km
21:06z VK1DA/2 1296MHz SSB QF45ME Andrew s58 r58 S2S VK2/ST-053 70 km
21:09z VK2HRX/P 144MHz SSB QF45FM Compton s57 r57 S2S VK2/IL-001 162 km
21:12z VK1MCW/P 1296MHz SSB QF44MQ Bill s59 r59 S2S VK1/AC-043 17 km
21:24z VK2HRX/P 1296MHz SSB QF45FM Compton s58 r55 S2S VK2/IL-001 162 km
21:26z VK1BG 1296MHz SSB QF44MS Ian s59 r59 26 km
21:30z VK1RX/2 1296MHz SSB QF44NV Al s59 r59 S2S VK2/ST-036 40 km
21:35z VK1CT 146.5MHz FM Chris s59 r59 S2S VK1/AC-034
21:45z VK1KW 2.3GHz SSB QF44MT Rob s55 r55 30 km
21:47z VK1RX/2 2.3GHz SSB QF44NV Al s59 r59 S2S VK2/ST-036 40 km
21:52z VK1AT 2.3GHz SSB QF44SI Jim s51 r41 S2S VK2/ST-001 43 km
21:55z VK1JA/P 2.3GHz SSB QF44NO Jason s59 r59 4 km
22:10z VK1MCW/P 2.3GHz SSB QF44MQ Bill s59 r59 S2S VK1/AC-043 17 km
22:13z VK1AT/2 2.3GHz SSB QF44SI Jim s52 r51 S2S VK2/ST-001 43km
22:15z VK1AT/2 144.2MHz SSB Jim s59 r59 S2S VK2/ST-001 43 km
22:23z VK1DA/2 144.2MHz SSB Andrew s59 r59 S2S VK2/ST-053 70 km
22:27z VK1CT/P 144.2MHz SSB Chris s59 r59 S2S VK1/AC-034 24 km

SOTA – Bobbara Mountain on 23cm 212 km to Nimmitabel

Sunday 10 March 2019 – Bobbara Mountain grid square QF45HI, 753 metres ASL is 86 km north-west of Canberra GPO, near the sleepy hollow township of Binalong, NSW.

I left home at 5:30 am for a 1.5 hour drive from Canberra heading north-west to Binalong. Access to the summit is via a public gravel road within a private property.

The summit hosts an air navigation facility en route radar, mobile phone and commercial radio services. The Trig station and summit surrounds are covered by a dense cover of dead thistle plants, it’s not a place to visit at the height of spring. To prevent your legs turning into blood soaked human pin cushions one needs to wear long pants. Seriously a field of dead thistle spikes crack a major ‘punch’ on soft human skin! 😦

My aim for today’s activation is to work 2m, 23cm and 13cm chasers in Canberra 86 km south-east on voice SSB and FM. To my great surprise Chris VK2DO located on the NSW south coast 188 km east (116 miles) and Rod VK2TWR 212 km south-east (136 miles) at his home QTH in Nimmitabel, NSW, popped up on 1296.150 SSB. That’s right 212 km on 1296 MHz at 2.5 watts, pretty good if I do say so myself. 🙂

At the conclusion of the 23cm activity I tested my new homebrew telescopic 2m 1/2 wave dipole. I sent a message to Wade VK1MIC via WhatsApp seeking his assistance. Wade called on 144.2 MHz using 2.5 watts QRP into a 2m 1/2 wave vertical located at his home in north Canberra (QF44NT). Signal reports were S52 and R51 over 76 km with mixed polarisation, that’s a good resul. 🙂

On 13cm 2.403 GHz Jason VK1JA and I attempted a contact over 97 km via aircraft enhancement. We failed to make the distance.

On 2m 144.2 MHz SSB all contacts were made at 5 watts using a 2m 3el yagi antenna.

During the descent my friend Andrew VK1DA suggested I drop in at his property near Yass. Thanks Andrew I was grateful for a nice cup of tea.


Sunrise 7:15 am


View east at 7:30 am


Bobbara Mountain Trig Station 753 metres ASL Latitude: -34.6393 , Longitude: 148.5903


Dual band 2m/70cm yagi and 13cm yagi. 23cm yagi is leaning against the tripod


SG-Lab 23cm transverter and a homebrew 12el DL6WU yagi beaming south-east towards Canberra. Operating frequency 1296.150 MHz


2m dipole mounted on a lightweight telescopic pole


close up view – 2m 1/2 wave dipole

Homebrew telescopic 2m dipole construction and assembly

Extract of VK1AD SOTA Activator Log: 9 March 2019 UTC – Bobbara Mountain QF45HI

Time Call Band Mode Notes
20:58z VK1KW 144MHz SSB QF44MT Rob s58 r55
20:59z VK2COW 144MHz SSB QF44OX Dimitris s57 r58
21:01z VK2DO 144MHz SSB QF54CH Chris s58 r55
21:03z VK1JA 144MHz SSB QF44NO Jason s55 r55
21:04z VK1MT 144MHz SSB QF44NM Matt s52 r33
21:14z VK1MIC 144MHz SSB QF44NT Wade s52 r51
21:15z VK1MA 144MHz SSB QF44MT Matt s51 r51
21:17z VK1FXNZ 144MHz SSB QF44NT John s55 r52
21:18z VK2TWR 144MHz SSB QF43PL Rod s52 r52
21:21z VK1JA 1296MHz SSB QF44NO Jason s55 r53 97 km
21:23z VK2DO 1296MHz SSB QF54CH Chris s55 r52 188 km
21:26z VK1BG 1296MHz SSB QF44MS Ian s58 r52 77 km
21:27z VK2TWR 1296MHz SSB QF43PL Rod s52 r51 212 km
21:28z VK1KW 1296MHz SSB QF44MT Rob s59 r59 74 km
21:32z VK2COW 1296MHz FM QF44OX Dimitris s59 r59 FM 71 km
21:37z VK1BG 1296MHz SSB QF44MS Ian s59 r59 74 km
22:11z VK1MIC 144MHz SSB QF44NT Wade s52 r51 75 km – 2m dipole

Photos: © Copyright 2019 Andrew VK1AD

SOTA – 23 cm action at Bald Mountain and Big Badja

Saturday 8 July 2017. Thee enthusiastic SOTA activators Andrew VK1MBE, Al VK1RX and myself have plans to activate three summits Bald Mountain, Big Badja Hill and Dampier in the Gourock and Deua National Parks, 2.5 hours south-east of Canberra.

Our plan is to rotate two SOTA stations between Bald Mountain VK2/SM-052 and Big Badja Hill VK2/SM-059 then take a convoy of two vehicles over to Dampier VK2/ST-007, 45 minutes south-east of Big Badja.

Left home at 6:30 am with Andrew VK1MBE, we met Al VK1RX 15 minutes later on the Monaro Hwy east of Calwell township.  Travel time to Bald Mountain is 2 hours.  Fastest route from Canberra is via the Monaro Hwy south to Bredbo. At Bredbo leave the Monaro Hwy and head east on Jerangle Road to Anembo.  At Anembo turn right on to Anembo Road and head south to intersect Slap Up Firetrail.  Follow Slap Up Firetrail to the summit of Bald Mountain.  Slap Up Firetrail passes directly over the summit.   One alternate route is via Cooma and Numeralla taking an extra 30 minutes.

Andrew VK1MBE and I set up at Bald Mountain while Al continued along Slap Up Firetrail to Big Badja Firetrail.  Al established his station at Big Badja for S2S contacts with Andrew and I plus Tony VK1VIC at Mt Cowangerong, Captains Flat Wx Radar installation.  Al at Big Badja, Andrew and I at Bald Mountain worked Rod VK2TWR at Nimmitabel on 23 cm for 5-9 reports each way, not bad for 2.5 watts output!   For Al and Andrew this event was their first shot at a 23cm SOTA activation.  We were grateful for Rod joining us on 23cm, thanks Rod.  🙂

Photos: © Copyright 2017 Andrew VK1AD

23cm action from Bald Mountain VK2/SM-052 at 1469 metres ASL, Grid Locator QF44SB

on the summit of Bald Mountain – 12el yagi beaming north-west to work VK1KW in Canberra over a 94 km path

I completed three 23cm QSOs including Rob VK1KW, Rod VK2TWR and Al VK1RX for a 23cm S2S QSO between Bald Mountain and Big Badja.  Tony VK1VIC/2 checked in for a 2m HT S2S QSO on 146.5 FM from Mt Cowangerong, 32 km north of Bald Mountain. Meanwhile Andrew worked one chaser Nev VK5WG on 40m. 40m band conditions were so bad Andrew was forced to set up his 80m antenna extensions.  If not for 80m, we wouldn’t have qualified before UTC midnight  🙂

Extract of VK1AD SOTA Activator Log: 7 July 2017 Bald Mountain

Time Call Band Mode Notes
23:15z VK1KW 1240MHz SSB %QRA%QF44MT% Rob s51 r51 1296.150 94 km
23:23z VK2TWR 1240MHz SSB %QRA%QF43PL% Rod s59 r58 1296.150 70 km
23:33z VK1RX/2 1240MHz SSB Al s59 r59 S2S VK2/SM-059 1296.150
23:47z VK2IO 3.5MHz SSB Gerard s59 r35, summit qualified
23:49z VK1MA 3.5MHz SSB Matt s59 r59
00:02z VK1RX/2 1240MHz SSB Al s59 r59 S2S VK2/SM-059 1296.150
00:13z VK1VIC/2 144MHz FM Tony s53 r51 S2S VK2/ST-001 146.5 2m HT 32 km

After 1 hour at Bald Mountain Andrew and I moved to Big Badja Hill.  En route we met Al halfway for a short break and a hot brew. Although the sun was visible through scattered clouds the feels-like temperature at 1400 metre ASL was closer to zero degrees C brrr.  Two layers of warm jackets, beanies (head and ear warmers) and glovers were the order of the day.  Yep the local temp was bloody cold!  😉

23cm action from Big Badja VK2/SM-059 at 1362 metres ASL, Grid Locator QF43SX

Andrew VK1MBE operating on HF 80m 3.605 MHz.  Antenna apex is a short 6 metres.

VK1MBE operating on 80m SSB

At Big Badja my best 23cm SSB contact for the day was a short QSO with Dave VK2JDS 322 km north near the townships of Orange and Bathurst NSW. The signal had a recognisable audible flutter, a characteristic of multi-path aircraft enhancement.  Midway along the 23cm signal path are the main Melbourne-Sydney and Sydney-Canberra commercial flight path corridors.

Extract of VK1AD SOTA Activator Log: 8 July 2017 Big Badja

Time Call Band Mode Notes
01:28z VK2TWR 1240MHz SSB %QRA%QF43PL%Rod s59 r59 1296.150 70 km
01:35z VK1RX/2 1240MHz SSB Al s59 r59 S2S VK2/SM-059 1296.150 8 km
01:36z VK1RX/2 1240MHz SSB Al s59 r59 S2S VK2/SM-059 1296.150 8 km
01:57z VK1VIC/2 144MHz FM Tony s57 r57 S2S VK2/ST-001 39 km using 2m HT
02:28z VK1MA 3.5MHz SSB Matt s59 r59
02:53z VK2JDS/P 1240MHz SSB %QRA%QF46PV% Dave s51 r51 1296.150 322 km

FT-817 IF 144.150 MHz SSB feeding a SG-Lab 23 cm transverter for output on 1296.150 MHz

23cm yagi beaming north to work VK2JDS over a 322 km path

Homebrew 23 cm 12el Yagi

three 23cm 1296.150 MHz SSB contacts, VK2JDS 322 km, VK1KW 94 km and VK2TWR 70 km

8 July 2017 – 23cm 1296 MHz SSB contacts

SOTA – Homebrew 23cm 12 element Yagi Antenna

Sunday 18 June 2017. I recently purchased a new 2.5 watt 23 cm transverter from SG-Lab in Sofia Bulgaria. The package includes a 2el HB9VC PCB yagi which has turned out to be a great addition for portable work, particularly from a hilltop with a good uninterrupted view of the horizon. Today from the summit of Mt Taylor VK1/AC-037 locator QF44MP, I worked Rod VK2TWR in Nimmitabel over 130 km, not bad for 2 watts in to a tiny PCB antenna.

While the PCB antenna is a great addition to the SOTA kit, be it for local summits or perhaps on a long hike 10 km or more, what I really need is an antenna with a fair amount of ‘oomph’ that’s non-techo speak for antenna gain, whilst keeping weight and size or length within reasonable limits.

For SOTA purposes, keeping antenna construction as simple as possible is a key attribute to a successful activation. When Murphy’s Law bites and it will, simplicity in design and construction is the key to a quick recovery.

I have decided to build two 23 cm (1296 MHz) 12 element Yagi antennas (DL6WU format) one with ‘handle’ space behind the reflector and the second to mount on a camera tripod. I figure two antenna options are better than one, plus phasing two in a stack would make for an interesting option!

To simplify the construction and to keep weight down I am using 18 mm square Western Red Cedar as the antenna boom. I am using Yagi Calculator, written by VK5DJ to generate the element lengths and spacings. At 1.2 GHz accuracy in element lengths and spacings are equally important. My spacing tolerances are +/- 0.5 mm while reflector and director element lengths are within 0.01 mm. Design details are shown at the end of this post.

Inputs to the Yagi Calculator software program include:

  • Frequency
  • Parasitic element diameter
  • Element mounting arrangement
  • Boom cross-section type
  • Boom cross-section dimension
  • Driven element cross-section type
  • Driven element cross-section dimensions and gap spacing
  • Non-metal boom
  • Number of director elements
  • Velocity Factor of RG316 69.5%

Materials list:

  • 2 * 1 metre lengths of 18 x 18 mm Western Red Cedar
  • 1.2 metre length of 3.1 mm aluminium rod purchased from Alucom. (Sufficient for one set of elements)
  • 100 mm length of RG316 for an 80 mm balun
  • 1 * RF N Type panel mount socket
  • 1 * 6 mm sprinkler riser (spacer)
  • 2 brass wood screws 25 mm long
  • Araldite or an epoxy resin to protect the feed point/balun
  • PCB Lacquer
  • Cabots Cabothane clear timber varnish
  • Sense of humour and patience 😉


  • Vernier caliper capable of measuring 0.01 of a millimetre
  • Marking Gauge
  • Square
  • Coping Saw
  • Pedestal Drill
  • 2.5 and 3.3 mm drill bits
  • Hobby knife
  • Scribe
  • Sharp pencil
  • Steel Rule 150 mm (6 inch)
  • Tape measure
  • Hand File fine-cut
  • Needle File
  • Soldering iron

Photos: © Copyright 2017 Andrew VK1AD

Boom Preparation

I used a marking gauge to mark the center line on opposite faces of the wooden boom.

marking the center line on opposing faces of the boom

Marking out element positions on each boom is a lot of fun, measure twice and mark once. I used the tip of the scribe to mark the hole positions. Make sure you mark the position of the driven element, you will need a reference point later.

Marking out Reflector, Driven and Director element positions on each boom

Two antenna booms – left boom will have space behind the reflector as a hand-held antenna. Right boom will have a tripod mount arrangement

Reflector and Director Elements

The 3.1 mm aluminium reflector and director elements are cut with a fine hacksaw then filed to their specified length. Each element is measured with a vernier caliper to within 0.01 mm. For the time being the elements are stored in a blank section while I continue work on the boom and the driven element.

Reflector and 10 director elements stored in a blank section

Folded dipole driven element

I marked out each of the folded dipole point-to-point measurements. I had a practice session at folding a driven element of 1.7 mm soft copper wire around a short length of 23 mm dowel. This is not the intended finished driven element, however it will serve me well for a shorter 5el yagi.

1st attempt at folding a 1296 MHz folded dipole by hand.

After three attempts at folding the driven element I have the finished product. As mentioned above the top element in the picture is 1.7 mm soft copper wire. Middle and bottom driven elements are each 2 mm solid copper wire found in the junk box. After cleaning the bottom element I will mount it to a female N Type panel mount socket. I will make good use of the spares. 🙂

thee 1296 MHz folded dipoles

Drilling the boom. I started with a 2.5 mm pilot drill followed by with a 3.3 mm drill bit. All holes were drilled using a drill press.

view down the length of the 23cm yagi, I’m pretty pleased with the alignment of each element, my eyesight hasn’t failed me yet! 🙂

Reflector and Director elements fitted to the non-handle version

Reflector and Director elements fitted to the handle version. I plan to cut a second set of parasitic elements

Back to the driven element..

I used emery paper to remove tarnish from the folded dipole which is now ready for a drop of solder. You will note the socket pin is soldered to one end of the open loop. This offsets the N Type socket by 3 mm to the left or right of the imaginary center line. It is important to remember the 3 mm offset when mounting the socket/dipole assembly to the boom, else the folded dipole will not be centered to the axis of the boom. Next fabricating the RG316 1/2 wave balun and cutting a garden sprinkler riser to make a pair of spacers to fit under the N Type socket.

Folded dipole and N Type socket ready for soldering. Use a small needle file to remove the socket plating and expose the brass.

Oh dear (or other choice words not suitable for this blog), working with RG316 takes a lot of patience, cutting and trimming the coax is as Andrew VK1DA explains ‘character building’. On my third attempt, that’s right 3rd attempt, I managed to not cut through the very fine multi strand center conductor. Phew, time for a stiff whisky! 🙂

If you know the secrets of working with RG316 particularly the center conductor, I’m all ears. BTW, I am using quality 316 (silver plated copper wire with a Teflon (PTFE) dielectric) from Mini Kits in South Australia, which isn’t the copper coated steel (CCS) variety. Now I know why the CCS version is popular with radio hobbyist like me, it’s difficult to cut through the center conductor. Ha ha..

RG174 may be a practical alternative. Remember to adjust the length based on the cable’s velocity factor (vf).

Next is the tricky part. Without destroying the integrity of the balun with an overzealous soldering iron, carefully solder the ends of the balun center conductor (I put so much effort in to that bloody balun!) to the driven element ends, plus solder the outer braid of each end to the N Type flange. This will test your spirit and endeavour to finish the project. Make sure you leave space around the flange mounting hole to accommodate a spacer. Good luck!

Folded dipole and balun (RG316) secured to a N Type panel mount. I will replace the ugly green tape with a section of heat-shrink

As mentioned earlier mounting the N Type socket requires a 3 mm offset due to the 5 mm spacing in the loop ends, if not the driven element will not be centered to the axis of the boom. Use the marker gauge to mark the offset line.

Feed point, folded dipole and balun assembly

Accurate spacing of the assembly above the boom will ensure the driven element is spaced evenly top and bottom. As best as you can have the center of the folded dipole in line with the reflector/director elements. Align the driven element to the markings on the side of the boom.

I cut two 13 mm lengths of 6 mm garden sprinkler riser tube. I am thankful the metal support screws have little to no influence on the VSWR reading. Before tightening the screws check the driven element is perpendicular to the boom. You can measure the spacing of the driven element between the tips of the 1st director and the tips of the reflector.

N Type flange mount and driven element assembly perfectly aligned to the first director and reflector elements.

Finished after 7 days of part-time construction work. You could easily build this antenna in a day. 🙂

Finished 12el 23cm Yagi ready for SOTA action!

To help protect the copper driven element from tarnish I applied a generous coating of PCB lacquer. To help prevent movement of the reflector and director elements, I applied a small amount of Araldite glue to each rod and mounting hole.

I haven’t decided whether to treat the wood with a coat of varnish or leave it as is.

Post update: 1 July 2017, mastering RG-316 1/2 wave balun.

Practice makes perfect, I’ve constructed a 3rd 1296 MHz folded dipole assembly. Best attempt thus far. Best approach to the 316 center conductor is to peel off small amounts of the Teflon dialectric until you expose the fine silver coated center conductor 🙂

Latest update: small wooden block glued to the boom

small wooden block to help protect the folded dipole and to prevent unnecessary movement

top side

Although not shown in the above picture, the boom now has a generous coating of Cabots Cabothane clear timber varnish. 🙂

Photos: © Copyright 2017 Andrew VK1AD

Published: 29 June 2017
Last Update: 5 July 2017

Output of VK5DJ Yagi Calculator

Balun design

RG316 1296 MHz 1/2 wave balun