SOTA Bowning Hill 2m and 23cm

Sunday 28 July 2017.  Bowning Hill summit VK2/ST-042 is on private property.  During the week I called the property owner seeking permission to get access to the summit.  Bowning Hill is 6m km north-west of Canberra GPO near the township of Yass, NSW.  Marino sheep graze on the property, evidence of the activity is abundant, sheep poop pellets (manure) are everywhere!

Interest in 23cm SOTA activations is growing around VK1.  Today Al VK1RX has plans to activate Livingstone Hill while a team of three activators led by Tony VK1VIC inluding Andrew VK1DA and Matt VK1MA are heading to Mt Foxlow also with 23cm gear.  ๐Ÿ™‚

Livingstone Hill VK2/SM-093 is 111 km south while Mt Foxlow VK2/ST-010 is an even 100 km south-east.

Around Canberra (VK1) and the nearby NSW (VK2) mountain peaks it’s rare to find a summit that one can drive up!  On this occasion I took advantage of a 4wd maintenance trail by driving to the summit and deploying a small folding table to operate from.  My car is 30 metres away from my operating position.   If not for a small table, the other option is to sit on the ground in a thick film of sheep poo  ๐Ÿ˜ฎ

Station gear:  Yaesu FT-817ND, SG-Lab 23cm transverter, Yaesu FT-60R HT, dual band 2m/70cm yagi, 12el 23cm yagi.    Batteries; 2.4 Ah 3S 12 volt LiPo and a 4.2 Ah 4S 13 volt LiFePO4.

As you can see in the photos the sun is shining yet the temperature on the summit is a chilly 1.8 degrees C with a cold westerly dropping the feels-like to sub-zero.

For a ‘warmer’ my first chaser was with Rob VK1KW on 2m 144.2 MHz followed shortly by a 2nd QSO on 23cm.  One down three to go!   It wasn’t long before Al VK1RX called on 1296.150 MHz only to report a strange high VSWR reading from his HB9CV 2el PCB yagi.    Al mentioned ice, that’s right frozen-H2O ice had formed on the leading edge of his antenna as a blast of cold moist air descended on Livingstone Hill.  See phots.  Al went QRT for a couple of minutes while he de-iced the antenna by placing the PCB in his warm pocket.

Five or so minutes later Al was back on air however by this time ice had formed on the coax feedline and the casing of his 23cm transverter.  Meanwhile I grabbed a 23cm chaser QSO with Ian VK1BG.   Rod VK2TWR followed Ian with a huge 5-8 signal report over a 200 km path from Nimmitabel.   Great that’s 4 QSOs on 23cm, summit qualified!

On 2m 144.2 MHz chasers included Matt VK1MT, Lawrence VK1LLW, Mike VK2AFW and Dave VK2DVM in Sydney.  While listening to Rob VK1KW calling CQ, I heard Jim VK3II 500 km south-west (near Phillip Island) responding to Rob.   Rob worked Jim with ease at legal power.  I quickly check FlightRadar24 on my iPad for aircraft between Jim’s position and Bowning Hill.  Two commercial aircraft in close proximity to each other were heading south along the Sydney – Melbourne flight path.  I mentioned to Rob VK1KW two aircraft would be midway between Bowning Hill and Jim’s radio shack in about 5 minutes.  With my paltry 5 watts I asked Rob to pass a message to Jim asking Jim to stick around for 5 minutes which thankfully he did.  As the aircraft approached the midway position I called Jim VK3II and to my delight he responded with a weak signal report, yep that’s right, a 5 watt 2m 144.2 MHz signal from a 3el beam, using aircraft enhance over 500 km.  Jim’s signal to me was 5-5, readable and well above the local noise floor. I have since shared the audio recording of my contact with Jim, with the VK1 group.   It’s moments like this where the efforts of going portable are all worth while!   ๐Ÿ™‚

15 or so minutes later at 23:35 UTC Andrew VK1DA called CQ SOTA on 23cm 1296.150 MHz from Mt Foxlow 100 km south-east.  Andrew is also using a 2.5 watt SG-Lab 23cm transverter, feeding an all-brass 4el yagi.  Andrew’s signal from Mt Foxlow was peaking 5-9 at Bowning Hill.  See photo and Google Earth profile.

Keen to bag Bowning Hill on 23cm, Tony and Matt both called in quick succession.  After working the Mt Foxlow team on 2m FM 146.500 simplex, I stuck around for UTC day change to complete a 3rd 23cm summit to summit (S2S) QSO with the crew at Foxlow.  ๐Ÿ™‚

VK1AD SOTA shack at Bowning Hill beaming south to Canberra

VK1AD 23cm yagi

Maps showing the radio signal path

Signal path – Bowning Hill to Livingstone Hill

Livingstone Hill to Bowning Hill terrain profile.  Courtesy of Google Earth

Signal path – Bowning Hill to Mt Foxlow

Mt Foxlow – Bowning Hill terrain profile.  Courtesy of Google Earth

Al VK1RX at Livingstone Hill.  Ice has formed on the leading edge of the HB9CV PCB 2el yagi.  Moisture on the PCB tracks is giving rise to a high VSWR. Photo courtesy of Al VK1RX.

VK1RX ice formed on the PCB antenna leading edge

Al’s frozen 23cm transverter and ‘iced’ coax feedline.  Photo courtesy of Al VK1RX

VK1RX at Livingstone Hill. Ice forming around the RG213 coax

Andrew VK1DA operating position at Mt Foxlow.  Photo courtesy of Andrew VK1DA

VK1DA’s 4el 23cm yagi antenna resting against a folding chair at Mt Foxlow

Extract of VK1AD SOTA Activator Log:  28 July 2017 Bowning Hill VK2/ST-042 on 23 cm 1296.150 MHz

Time Call Band Mode Notes
21:49z VK1KW 144MHz SSB Rob s59 r59 QF44MT 144.2
21:51z VK1KW 1240MHz SSB %QRA%QF44MT% Rob s59 r59 1296
22:13z VK1RX/2 144MHz SSB Al s59 r59 S2S QF44NG 144.2
22:14z VK1BG 144MHz SSB Ian s59 r59 QF44MS 144.2
22:15z VK1BG 1240MHz SSB %QRA%QF44MS% Ian s59 r59 1296
22:19z VK1RX/2 1240MHz SSB Al s59 r58 S2S VK2/SM-093 1296 111 km
22:22z VK1MT 144MHz SSB Matt s59 r59 144.2
22:25z VK2TWR 1240MHz SSB %QRA%QF43PL% Rod s58 r58 1296 200 km
22:39z VK1LWW 144MHz SSB s52 r53 144.2
22:43z VK2AMF 144MHz SSB Mike s57 r57 QF44PU 144.2
23:17z VK3II 144MHz SSB Jim s55 r51 QF21RN 500 km at 5 watts
23:18z VK2DVM 144MHz SSB Dave s58 r58 Sydney
23:35z VK1DA/2 1240MHz SSB Andrew s59 r59 S2S VK2/ST-010 1296 100 km
23:36z VK1VIC 1240MHz SSB Tony s59 r58 S2S VK2/ST-010 1296
23:40z VK1MA/2 1240MHz SSB Matt s59 r59 S2S VK2/ST-010 1296
23:42z VK1DA/2 1240MHz SSB Andrew s59 r59 S2S VK2/ST-010 1296
23:50z VK1MA/2 144MHz SSB Matt s59 r59 S2S VK2/ST-010 146.5
23:53z VK1VIC/2 144MHz SSB Tony s59 r59 S2S VK2/ST-010 146.5
00:01z VK1DA/2 1240MHz SSB Andrew s59 r58 S2S VK2/ST-010 1296
00:02z VK1MA/2 1240MHz SSB Matt s59 r59 S2S VK2/ST-010 1296
00:02z VK1VIC/2 1240MHz SSB Tony s59 r59 S2S VK2/ST-010 1296
  • 23cm Awards:
    • 23cm Summit to Summit (S2S) 111 km, working Al VK1RX at Livingstone Hill
    • 23cm 200 km working Rod VK2TWR at Nimmitabel
  • Personal best:
    • working Jim VK3II on 2m 144.2 MHz SSB over 500 km with 5 watts
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SOTA – 23 cm S2S – Livingstone Hill to The Peak 78 km

Sunday 23 July 2017.  During the week I pushed an email to the VK1 SOTA group seeking interest in a 23cm SOTA activation planned for Sunday 23 July 2017.  Al VK1RX called me Saturday evening suggesting we try a 23cm 1296.150 SSB Summit to Summit (S2S) contact between Livingstone Hill and The Peak, that’s 78 km (48 miles) as the crow flies, locator QF44NG to QF43NN.   Al was very keen to activate The Peak (1230 m ASL) for 11 points and thought that a 23 cm SSB S2S contact whilst achievable, would present a good challenge @ 2.5 watts output.  We discussed expected signal reports over a 78 km path to which we pondered the possibility of achieving a S2S contact, we agreed a 5-3 signal report would be a satisfactory outcome at 2.5 watts.  Little did we know…

Livingstone Hill is a 40 minute drive south of Canberra near the country township of Michelago.   The Peak is a 1.5 hour drive south of Canberra along the Monaro Hwy via Cooma and Rock Flat.  Both summits feature in the New South Wales (NSW) Snowy Mountains region, of course Al is much closer than I to the actual Snowy Mountains Alpine region.

Livingstone Hill near Michelago township

beautiful chilly morning at Livingstone Hill Trig Station

8:52 am – One hour in to the activation the temperature is a cool 3 degrees C at (22:52 UTC)

VK1AD 23cm SOTA station – Yaesu FT-817 IF on 144.150 MHz into a SG-Lab 23cm transverter.  Antenna feedline is a 1 metre length of LMR195 coax cable.   FT-817 is powered by a 12 volt 3S 2.4 Ah LiPo battery while the SG-Lab 23cm transverter is powered by a 13.2 volt 4S 4.2 Ah LiFePO4 battery.  The transverter draws 80 mA on receive and 800 mA (0.8 amps) on transmit.

VK1AD 23 cm SOTA Shack at Livingstone Hill.  My 23cm PCB antenna used later in the activation  is sitting on a plastic container.

VK1AD beaming south to The Peak VK2/SM-068

VK1AD 23 cm SOTA station.  View east Tinderry Range at 1560 m ASL

VK1RX SOTA Shack at The Peak beaming north to Livingstone Hill over a 78 km path.  Al is using an ICOM IC-706 IF at 144.150 MHz SSB mode feeding a SG-Lab 23cm transverter for output on 1296.150 MHz SSB.  Al’s transverter and antenna are both mounted above the tripod pan head.  You can see the IC-706 sitting on the concrete pad (trig point) below the tripod.  His 23 cm antenna feedline losses are negligible.

Al reported strong winds at the summit.  In the photo you can see AL gathered a few rocks to stabilise the tripod in the face of a strong north-westerly wind.

I started my SOTA CQ calls at 2155 UTC with the antenna beaming south to Nimmitabel.  At 21:59 Al responded to my call with an unexpected 5-9 signal report, a huge signal, way beyond our expectations.  ๐Ÿ™‚      You know what that means, that’s right we need a new 23cm S2S challenge with two summits 100 km+ apart working our way up to 200 km+.

Having over achieved with 5-9+ signal reports later in the activation we decided this 23cm S2S challenge would not be complete without one attempt at using PCB yagi antennas at our respective summits.  Did we make the distance, we sure did!  Signal levels were peaking 5-9 each way.  ๐Ÿ˜‰

On 23 cm Al and I went on to work Rob VK1KW, Ian VK1BG, Rod VK2TWR and Matt VK1MA.

VK1RX 23cm SOTA Shack at The Peak

Extract of VK1AD SOTA Activator Log:  23 July 2017 Livingstone Hill VK2/SM-093 on 23 cm 1296.150 MHz

Time Call Band Mode Notes
21:59z VK1RX/2 1240MHz SSB Al s59 r59 S2S VK2/SM-068 1296 78 km
22:08z VK1KW 144MHz SSB QF44MT Rob s59 r58 61 km
22:11z VK1MT 144MHz SSB QF44NM Matt s59 r59 30 km
22:15z VK1KW 1240MHz SSB %QRA%QF44MT% Rob s58 r58 1296 61 km
22:16z VK1BG 1240MHz SSB %QRA%QF44MS% Ian s59 r59 1296 56 km
22:26z VK2TWR 1240MHz SSB %QRA%QF43PL% Rod s59 r57 90 km
22:34z VK1RX/2 144MHz SSB QF43NN Al s59 r59 S2S 144.2 78 km
22:39z VK1BG 433MHz SSB QF44MS Ian s59 r58 432.15 56 km
22:39z VK1KW 433MHz SSB QF44MT Rob s51 r55 432.15 61 km
23:02z VK2NSS 144MHz SSB Steve s55 r55 45 144.2 86 km
23:18z VK1MA 1240MHz SSB %QRA%QF44MT% Matt s51 r31 1296 61 km

VK1AD 23cm 12el Yagi.  The mountain range to the right is Clear Range spanning 1300 m to 1500 m ASL.

looking down the barrel of a 23cm 12el yagi – Al VK1RX is well over the horizon 78 km south

23cm 12el yagi

23 cm signal from Livingstone Hill to The Peak bearing 180 degrees south over a 78 km path

SOTA – Microwave Award 300 km at 23cm

SOTA Microwave Awards โ€“ Simplex Operations on 23cm

Today I received a SOTA 23 cm Microwave Certificate Awards from Barry GM4TOE, SOTA Awards Manager, UK.

8 July 2017 – SOTA 300 km 23 cm Microwave Award โ€“ Operating on 23 cm 1296.150 MHz SSB from Big Badja VK2/SM-059, I worked Dave VK2JDS locator QF46PV, over a 322 km path at 2.5 watts output. ๐Ÿ™‚

SOTA 300 km 23 cm Microwave Award โ€“ 8 July 2017

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.ย  Travel time to Bald Mountain is 2 hours.ย  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.ย  At Anembo turn right on to Anembo Road and head south to intersect Slap Up Firetrail.ย  Follow Slap Up Firetrail to the summit of Bald Mountain.ย  Slap Up Firetrail passes directly over the summit.ย ย  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.ย  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.ย  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! ย  For Al and Andrew this event was their first shot at a 23cm SOTA activation.ย  We were grateful for Rod joining us on 23cm, thanks Rod.ย  ๐Ÿ™‚

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.ย  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. ย If not for 80m, we wouldn’t have qualified before UTC midnightย  ๐Ÿ™‚

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.ย  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.ย  Two layers of warm jackets, beanies (head and ear warmers) and glovers were the order of the day.ย  Yep the local temp was bloody cold!ย  ๐Ÿ˜‰

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

Andrew VK1MBE operating on HF 80m 3.605 MHz.ย  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.ย  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 ๐Ÿ˜‰

Tools:

  • 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

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. ๐Ÿ™‚

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! ๐Ÿ™‚

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! ๐Ÿ™‚

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. ๐Ÿ™‚

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 havenโ€™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 ๐Ÿ™‚

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. ๐Ÿ™‚

Photos: ยฉ 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