SOTA – 2.4 GHz Yagi failed at Mt Tumorrama VK2/SW-027

Sunday 27 May 2018 7:30 am Mt Tumorrama. My homebrew 2.4 GHz Yagi had failed at when I noticed the 2.4 GHz 2.5 watt SG-Lab transverter SWR LED had changed to RED! Hmm.. bugger that wasn’t expected.

I didn’t have time or the tools to repair the antenna so I persisted with my backup antenna a 2.4 GHz Bi-Quad (below). I was pleasantly surprised by the performance of the Bi-Quad by successfully working Al VK1RX/P for two SOTA S2S contacts at VK1/AC-023 and VK2/ST-005, Dimitris VK2COW over a 64 km path and Matt VK1MA/P S2S at Mt McDonald VK1/AC-048 along a 39 km path of multiple 1200 m ASL mountain ranges.

Back to the 2.4 GHz Yagi. Today, using a pair on 2.5 magnification glasses I took a closer look at the folded dipole assembly. This is what I found 😦

2.4 GHz folded dipole assembly

Close up – 2.4 GHz folded dipole assembly – You never know what can go wrong at SOTA summit!

Let’s crack open the soldering iron and fix that bad boy.

Wow a clean break. A stress crack between the SMA center pin and the copper dipole

Earlier photo of the assembled 2.4 GHz Yagi

Balun impedance transformer – 43 mm length of RG402

For info – 2.4 GHz Bi-Quad photo taken earlier in March 2018

March 2018 – 2.4 GHz Bi-Quad photo courtesy of VK1MIC

73, Andrew VK1AD

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SOTA – 2.4 GHz 150 km Summit to Summit

Sunday 22 April 2018 -The Peak 1230 m ASL QF43NN Snowy Mountains NSW

I have organised a S2S challenge with Al VK1RX where we will attempt a 150 km path on 23cm (1296 MHz) and 13cm (2.4 GHz) at 2.5 watts SSB.

Radio Equipment:

Profile

Path – The Peak QF43NN to Spring Hill QF44VN

Photos: © Copyright 2018 Andrew VK1AD

Video – 12 minute video starts with a couple of contacts on 2m SSB before changing to our S2S attempt on 13cm 2.4 GHz SSB.  Water condensation from the fog was a major issue.  The 13cm SG-Lab transverter is crudely protected by my ball cap!

Photos: © Copyright 2018 Andrew VK1AD

The Peak trig station identified as Hudsons Peak trigonometric station

Apart from the great success in working Al VK1RX/2 on 13cm, my best contact on 2m SSB was Dave VK2DVM in Sydney over a 355 km path at 5 watts from the FT-817.  I happy to call that QSO as ‘VHF DX’.

Extract of VK1AD SOTA Activator Log: 22 April 2018 – The Peak

Time Call Band Mode Notes
22:01z VK1FXNZ 144MHz SSB QF44NT John s58 r58 139 km
22:06z VK1JA 144MHz SSB QF44NO Jason s51 r52 114 km
22:07z VK1KW 144MHz SSB QF44MT Rob s59 r57 138 km
22:09z VK2COW 144MHz SSB QF44OX Dimitris s51 r51 157 km
22:11z VK1RX/P 144MHz SSB Al s58 r58 S2S VK2/ST-036 150 km
22:18z VK1MA 144MHz SSB Matt s58 r55 QF44MT 138 km
22:19z VK1MT 144MHz SSB Matt s58 r58 QF44NM 105 km
22:26z VK2TWR 1240MHz SSB QF43PL Rod s58 r57 13 km
22:28z VK1BG 1240MHz SSB QF44MS Ian s58 r58 133 km
22:29z VK1DO 1240MHz SSB QF44PO Chris s51 r55 114 km
22:31z VK1MT 1240MHz SSB QF44NM Matt s52 r51 105 km
22:33z VK1RX/2 1240MHz SSB Al s56 r56 S2S VK2/ST-036 150 km
22:37z VK1MA 1240MHz SSB QF44MT Matt s51 r31 138 km
22:38z VK1KW 1240MHz SSB QF44MT Rob s51 r51 138 km
22:47z VK2DVM 144MHz SSB QF56OG Dave s56 r55 355 km
22:48z VK1MIC 144MHz SSB Wade s58 r58 S2S VK1/AC-035 145km
23:14z VK1RX/2 2.3GHz SSB Al s51 r51 S2S VK2/ST-036 150km
23:21z VK1JA 2.3GHz SSB QF44NO% Jason s51 r41 114 km
23:48z VK1RX/2 2.3GHz SSB Al s52 r55 S2S VK2/ST-036 150 km
00:01z VK1RX/2 144MHz SSB Al s59 r59 S2S VK2/ST-036 150 km
00:06z VK1MA 144MHz SSB QF44MT Matt s54 r52 138 km

11 am local time, just as the fog is starting to lift, it’s time to head back to Canberra.  Next year I will visit this summit in early summer.

View from the car after leave The Peak – extinct volcano

Railway to nowhere!  Disused railway between Cooma and Nimmitabel

SOTA – Mt Ginini 13cm 2.4 GHz Activation

Saturday 31 March 2018, 2.4 GHz activation from Mt Ginini VK1/AC-008 1760m ASL QF44JL, Bimberi Wilderness

The VK1 SOTA 13cm group has organised 1.2 and 2.4 GHz SOTA activations of Mt Ginini VK1/AC-008, Mt Mundoonen VK2/ST-053 and Mt Stromlo VK1/AC-043. A small group of dedicated radio amateur microwave chasers have offered to take part. You can find signal report details at the bottom of this page. First are the direct RF path profiles:

23cm (1.2 GHz) and 13cm (2.4 GHz) RF path profiles:

  • Mt Ginini QF44JL to VK1RX at Mt Mundoonen 810m ASL, QF45ME – 82 km
  • Mt Ginini QF44JL to VK1ATP at Mt Stromlo 782m ASL, QF44MQ – 32 km
  • Mt Ginini QF44JL to VK1JA at Wanniassa QF44NO – 31 km
  • Mt Ginini QF44JL to VK1DSH & VK2COW both at Gundaroo QF44OX – 65 km

Path Profiles

Mt Ginini VK1/AC-008 – Mt Mundoonen VK2/ST-053

Mt Ginini to Mt Mundoonen path profile 82 km

Mt Ginini to Mt Mundoonen

Mt Ginini – Gundaroo QF44OX 65 km

Mt Ginini – Gundaroo QF44OX

Mt Ginini to Gundaroo QF44OX

Mt Ginini – Wanniassa QF44ON 31 km

Mt Ginini – Canberra QF44ON

Mt Ginini to Canberra QF44ON

Mt Ginini – Mt Stromlo QF44MQ 32 km. The blocking feature is Tidbinbilla Mountain Range. This may help to explain the signal attenuation between Mt Ginini and Mt Stromlo. A knife-edge path over Tidbinbilla Mountain is possible.

Mt Ginini to Mt Stromlo QF44MQ profile

Mt Ginini to Mt Stromlo QF44MQ

Equipment:

  • Yaesu FT-817ND
  • SG-Lab 23cm transverter
  • SG-Lab 13cm transverter
  • 12el 23cm Yagi
  • 20el 13cm Yagi
  • 3el 2m Yagi
  • Yaesu FT60R HT
  • 8.4Ah 4S LiFePO4 battery
  • 12 volt 4-way PowerPole distribution box
  • 2 * 1.4 metre tripods
  • Assorted cables, RG-402 and LMR-195
  • Prismatic Compass for Yagi bearings
  • 7 metre telescopic pole
  • Pole guy kit
  • HF linked inverted V antenna
  • Food and water

I qualified on 2m, 23cm and 13 cm bands with at least four unique callsigns worked on each band. Signal reports on 23 and 13cm exceeded expectations. Very happy with the outcome. The 13cm group VK1DSH, VK2COW, VK1JA, VK1RX and VK1AD experimented with SSB and FM voice modes.

What’s next? Find two or more summits each 100 km apart. 🙂

Extract of VK1AD SOTA S2S Log: 30 March 2018 (UTC) Mount Ginini

Time Call Band Mode Notes
21:07z VK1JA 144MHz SSB Jason s59 r59 Canberra
21:08z VK2DVM 144MHz SSB Dave s59 r58 Sydney
21:09z VK2COW/P 144MHz SSB Dimitris s59 r59 QF44OX
21:11z VK1MA 144MHz SSB Matt s59 r59 QF44MT
21:18z VK1RX/2 144MHz SSB Al s59 r59 S2S QF45ME
21:19z VK1ATP/P 144MHz SSB Paul s53 r53 S2S VK1/AC-043 32 km
21:24z VK1DSH/P 1240MHz SSB QF44OX Dale s59 r59 65 km
21:26z VK1RX/2 1240MHz SSB Al s59 r59 S2S VK2/ST-053 82 km
21:27z VK1MA 1240MHz SSB QF44MT Matt s59 r59 41 km
21:29z VK1ATP/P 1240MHz SSB Paul s52 r52 S2S VK1/AC-043 32 km
21:35z VK1KW 1240MHz SSB QF44MT Rob s59 r59 41 km
21:40z VK1BG 1240MHz SSB QF44MS Ian s59 r59 37 km
21:49z VK1JA 2.3GHz SSB QF44NO Jason s59 r59 31 km
21:51z VK1DSH/P 2.3GHz SSB QF44OX Dale s59 r59 65 km
22:00z VK1RX/2 2.3GHz SSB Al s58 r58 S2S VK2/ST-053 82 km
22:05z VK2COW/P 2.3GHz SSB QF44OX Dimitris s59 r59 65 km
22:44z VK1RX/2 2.3GHz FM Al s58 r58 S2S VK2/ST-053 82 km

2.4 GHz Yagi Testing

With the 20el 2.4 GHz yagi construction complete its time to test the antenna in the real world, theoretical gain is 15dB. Just to be perfectly clear, this is not a laboratory test, I don’t have expensive test instrument gear. I have taken my gear to the summit of Mt Stromlo VK1/AC-043 and my good friend Al VK1RX has assembled his 2.4 GHz SOTA station at the summit of Mt Ainslie VK1/AC-040 14 km (8.7 miles) north of Stromlo.

20180315_172252.jpg

My reference antenna is a tiny 2.4 GHz ‘Big Wheel’ antenna, 2 dB gain over a dipole. Al’s 13cm yagi is 24 elements while his reference antenna is a simple 13 cm half-wave dipole.

To reduce signal losses in the feedline, I have mounted the 2.4 GHz transverter close to the antenna. Feedline is a 150 mm length (6 inches) of 50 ohm RG402 coax terminated in male SMA connectors at each end.

For obvious reasons with yagi antennas pointing at each other signal reports were excellent, we each had line-of-sight to the target summit. Nevertheless we conducted experiments with our respective antennas opposed (back to back) and at right angles to each other. We each found a deep null in signal reception when my antenna was pointing due east and Al’s antenna pointing due west, a good result. 🙂

FT-817 signal report indicators are generally of use to the operator only and no one else. I honestly can’t provide reliable signal reports as one might measure using a calibrated s-meter. What I can say is using the ‘Big Wheel’ antenna Al’s received signal, with Al transmitting into a 2.4 GHz half-wave dipole, was 5-7 to 5-8 (uncalibrated) and later using the 20el Yagi Al’s indicated signal display was full scale on the 817, all signal blocks illuminated as S++ which if material on the internet is to be believed is somewhere in the order of 12 to 15 dB greater than S8. The popular myth of 6dB per signal block is just that, a myth.

Our practical test was fruitful to the point where we now have a benchmark to work with. Next our plan is to operate from two summits 50 km apart followed by a second pair 100 km apart and so on. Can we crack 150 km on 2.4 GHz with 2.5 watts?

SOTA – VK1 2.4 GHz S2S Party

Sunday 4 March 2018. VK1 is holding an early morning SOTA 2.4 GHz and 1.2 GHz S2S Party with VK1 microwave activators setting up on five peaks plus Bill VK1FWBK on 2m FM. It’s 7:30 am (20:30 UTC), Wade VK1MIC and I have walked 3 km to set up two stations on the summit of Mount McDonald VK1/AC-048 789 metres ASL, grid square QF44LQ. Wade has deployed a HF + 2m station and I have set up my 1.2 and 2.4 GHz SG-Lab transverters. Liaison with local VK1 stations was planned for 146.500 FM, however due to competing SOTA chaser traffic we thought it best to move to 146.525 FM. For future microwave activations the VK1 group will liaise on 146.525 FM.

So who’s on which SOTA peak?

As mentioned Wade VK1MIC and I have chosen Mount McDonald primarily as the summit is free of trees and vertical obstructions as viewed to the north, east and south. The bulk of my fellow SOTA activators are east of Mt McDonald. I figured Mt McDonald is the best strategic option.

To my east, Bill VK1FWBK was an early riser making the top of Mt Majura with a 2m HT, Matt VK1MA has set up on Mt Stromlo VK1/AC-043, Al VK1RX is ready to go on Black Mountain VK1/AC-042 with a 24el homebrew yagi while Paul VK1ATP is assembling a 2.4 GHz Grid Pack antenna plus a Cantenna on the summit of Mt Ainslie VK1/AC-040. Mt Ainslie is 20 km east of my position at Mt McDonald.

That’s five out of six activators, who else volunteered to get out of bed at 5 am? Andrew VK1DA/2 has opted to set up on his so-called local peak, Mt Mundoonen 10 km north of Yass in the state of NSW and 54 km north of Mount McDonald. Andrew has a hombrew 2.4 GHz transverter plus a SG-Lab 1.2 GHz transverter. I have line-of-sight to Mt Mundoonen, a 2.4 GHz S2S with Andrew should be a formality.

Terrain between AC-048 and ST-053 54 km north

Terrain between AC-048 and ST-053, 54 km north

So how did we go on 2.4 GHz? The group of five in Canberra; Matt, Al, Paul, Wade and myself worked each other with ease, 5-9 signal reports all round. On the other hand working Andrew VK1DA/2 at Mt Mundoonen 54 km north of Mount McDonald became a major challenge for all. Andrew was experiencing 2.4 GHz equipment problems so he set about rectifying the problem. In the meantime the group of five, including Andrew moved to 1.2 GHz, 1296.150 MHz for a second round of S2S contacts. All five summit stations worked each other with ease, 1296 MHz was a pushover.

With 1.2 GHz done and dusted, the group moved back to 2.4 GHz looking for a weak signal from Andrew at Mt Mundoonen. Finally it came, at first a weak distant voice in the noise followed by a sudden lift in signal strength for a readable report at 5-2. On Andrew’s side my SSB signal was 4-1 sufficient to confirm signal reports, exchange summit codes followed by ‘QSL’.

Success! Qualification on 1.2 GHz and 2.4 GHz plus a bonus 2m S2S with Bill VK1FWK. 🙂

Extract of VK1AD SOTA S2S Log: 3 March 2018 (UTC) Mount McDonald

Time (UTC) Station Summit My Summit Band Mode Distance (km)
20:39 VK1FWBK/P Mt Majura Mount McDonald 146MHz FM 23
20:43 VK1RX/P Black Mountain Mount McDonald 2.3GHz SSB 15
21:09 VK1MA/P Mt Stromlo Mount McDonald 2.3GHz SSB 6
21:24 VK1ATP/P Mt Ainslie Mount McDonald 2.3GHz SSB 20
21:34 VK1MA/P Mt Stromlo Mount McDonald 1240MHz SSB 6
21:38 VK1RX/P Black Mountain Mount McDonald 1240MHz SSB 15
21:43 VK1DA/2 Mt Mundoonen Mount McDonald 1240MHz SSB 54
21:50 VK1ATP/P Mt Ainslie Mount McDonald 1240MHz SSB 20
22:23 VK1DA/2 Mt Mundoonen Mount McDonald 2.3GHz SSB 54

Photos: © Copyright 2017 Andrew VK1AD

View east – sunrise from Mt McDonald

View south over Bullen Range and Namadgi National Park.

13cm Bi-Quad is facing east working stations over a short distance (20 km) to Canberra

I’m still considering the Bi-Quad mounting arrangement – for now the 2.4 GHz Bi-Quad is resting on two blocks of wood.

SG-Lab transverter IF frequency 435.150 MHz is derived from the FT817 at 500 mW. Transverter local oscillator frequency (LO) is set to 1968 MHz for 2.5 watts RF output on 2403.150 MHz.

SG-Lab 13cm 2.4 GHz transverter with a 2.4 GHz Bi-Quad resting on two small blocks of wood. Photo courtesy of Wade VK1MIC

Andrew VK1AD in his favourite position – lying in the Aussie dirt on a mountain peak 🙂

IMG_6367.jpg

Andrew VK1AD SOTA shack. The white pole is a 2m half-wave vertical. Photo courtesy of Wade VK1MIC

23cm Bi-Quad facing north to Mt Mundoonen – signal report exchange with Andrew VK1DA/2 was 5-9

20180304_084030

23cm 1.2 GHz Bi-Quad antenna and transverter mounted on a tripod

Post update: photo supplied by Al VK1RX of his 13cm transverter and 2.4 GHz yagi set up on Black Mountain

Photo courtesy of Al VK1RX

First published: 5 March 2018

Last Update: 6 March 2018

Antenna Project – 2.4 GHz 13cm Yagi for SOTA

I recently purchased a 13cm transverter from SG-Lab. I have constructed a 13cm Bi-Quad antenna for use on local suburban SOTA summits, however I will need a high gain 2.4 GHz antenna for SOTA activations 100+ km from Canberra, but not one as bulky as a Grid-pack antenna or parabolic dish. I have decided to construct a 20 element 2.4 GHz (DL6WU format) yagi. I used VK5DJ’s Yagi Calculator software to generate yagi element dimensions, tolerance is a BIG fat Zero +/- mm. Boom material is wood 18 mm square Western Red Cedar, very stable material. When finished the boom will be coated with a generous coating of Cabothane, hard wearing waterproof clear timber varnish.

I am using the same construction technique as I did for the 12el 23cm (1296 MHz) Yagi. Reflector and driven elements are 3.1 mm aluminium rod, I have a 2 metre length on hand. Drive element material is 1.6 mm copper wire folded by hand, inside diameter is 22 mm. 🙂

13cm 2.4 GHz Yagi Boom Preparation

13 cm 2.403 GHz Yagi Dimensions

VK5DJ – 2.4 GHz DL6WU Yagi Dimensions

12el 23cm Yagi and the new 20el 13cm Yagi with reflector and director elements. Folded dipole is next.

23cm yagi and 13 cm yagi

Testing my first prototype 2.4 GHz folded dipole

2.4 GHz Folded Dipole Assembly

13cm 2.4 GHz folded dipole – 137 mm length of 1.6 mm copper wire. 2403 MHz Impedance balun – 43 mm length of RG402, velocity factor = 69.5%.

13cm folded dipole and balun assembly mounted on a SMA panel mount

SMA Panel Mount

2.4 GHz folded dipole assembly mounted on 6 mm nylon spacers

Homebrew 2.4 GHz Yagi – Balun and Folded dipole assembly

20el 13cm 2.4 GHz DL6WU Yagi – reflector, driven element, D1…D18

20el 13cm 2.4 GHz DL6WU Yagi

20el 2403 MHz (2.4 GHz) DL6WU yagi antenna

First Published: 3 March 2018
Last Update: 3 March 2018

Antenna Project – 2.4 GHz 13cm Bi-Quad for SOTA

I recently purchased a 2.4 GHz transverter from SG-Lab in Sofia, Bulgaria. To get you on air the transverter is shipped with a 2.3 GHz 4el HB9CV PCB yagi which at 2.4 GHz has a VSWR 1.7:1, that’s easy to fix. 🙂

In addition to using the supplied HB9CV PCB yagi, I will construct a 22el yagi (in progress) and the Bi-Quad directional antenna mentioned in this post.

You may recall I’ve had good results on 23cm 1296 MHz with a Bi-Quad antenna, also known as a double-quad antenna, so I hope to repeat similar results on 13cm 2.4 GHz. This post describes how I constructed a 2.4 GHz Bi-Quad directional antenna. The VK 2.4 GHz narrow band SSB call frequency is 2403.150 MHz.

13cm Bi-Quad Antenna

For dimensions see: Changpuak Bi-Quad online calculator

2.4 GHz Bi-Quad Antenna Dimensions – courtesy of changpuak.ch

Materials

  • Double-sided copper clad PCB 130 * 85 mm (I had this piece on hand)
  • 50 mm length of semi-rigid 50 ohm RG402 (mini kits)
  • Female SMA socket to RG402 (solder type)
  • 300 mm length of 2 mm copper wire (junk box)
  • 2 * 15.2 mm stand-off insulators. I used 7 mm diameter plastic sprinkler riser tube
  • 2 * Cable ties
  • PCB enamel

Prepare a double-sided copper clad board 130 mm * 85 mm. Drill the center of the board staring with a pilot drill 1.5 mm followed by a 3 mm drill bit. Use a taper ream to finish the hole.

Debur the hole and edges of the board.

Prepare a 1/2 wave length (43 mm) of 50 ohm RG-402 and a female SMA. RG-402 has a velocity factor of 69.5%.

Assemble connector to RG402 feedline

Prepare the Bi-Quad driven element, 30 mm per side.

2.4 GHz Bi-Quad antenna parts – reflector, RG402 feedline and driven element

Assemble driven element and feedline

preparation for soldering driven element to RG402 feedline

preparation for soldering the driven element to RG402 feedline

Center of the driven element is soldered to the RG402 inner conductor. The two open ends are soldered to the RG402 copper shield

Bi-Quad driven element held in place for soldering

Almost finished – adjust the spacing between the reflector and driven element for a 1:1 VSWR. In this case to achieve a 1:1 VSWR the spacing is 15.2 mm, a small variation (0.4 mm) to the calculator dimensions table.

2.4 GHz Bi-Quad Antenna

2.4 GHz Bi-Quad Directional Antenna

Spacers – 15.2 mm length of 7 mm plastic riser tube, measured with a vernier caliper. Solder the RG402 shield to the PCB front and rear.

RG402 passes through the reflector. Spacing is 15.2 mm

Assembly finished, 9dB gain Bi-Quad antenna

Rear of the reflector – RG402 feedline and female SMA connector

Enjoy building your own 2.4 GHz Bi-Quad. 🙂

To finish off, below is a picture of the supplied 2.3 GHz 4el HB9CV Yagi. This antenna is designed for 2.3 GHz, at 2.403 GHz the VSWR is 1.7:1. To change the antenna’s resonant frequency to the VK SSB call frequency (2403 MHz) I trimmed 2 mm off each side of the two active elements (copper tracks). I left the director elements untouched.

2.3 GHz 4el HB9CV Yagi

20180225_102206

2mm trimmed from each side of the active elements.

First published: 19 February 2018
Last Update: 25 February 2018