SOTA – 6m Challenge Sporadic E from Booroomba Rocks

Sunday 13 December 2015.  I’m at the summit of Booroomba Rocks, Namadgi National Park VKFF-0377 to operate my amateur radio gear for the Summits on the Air (SOTA) 6m (50 MHz) and 10m (28 MHz) Challenge.  The ‘challenge’ is to work as many unique amateur radio callsigns on 50 MHz or 28 MHz from any country in the world and from as many unique SOTA summits you can get to.  The method of scoring is the number of unique callsigns worked by the activator (me) on 6m or 10m or both bands, multiplied by the number of unique SOTA peaks activate in two defined periods:

  • 1st period – 15 May 15 – 14 Aug 15 inclusive; and
  • 2nd period – 14 Nov 15 – 13 Feb 16 inclusive.

The 1st period closely aligns to the northern hemisphere spring/summer while the 2nd period closely aligns to the southern hemisphere spring/summer.  Both challenge periods are open to amateur radio operators in both hemispheres.   Why chose a segment of spring/summer in each hemisphere?  You can work it out, keep reading.

I’m hoping for a 10m DX opening and a chance to work unique callsigns in North America and Japan.   If 10m propagation is good, I may hear local amateur radio stations in the regions of Western Australia, Northern Territory, South Australia and Queensland.  Victoria, NSW and Tasmania are considered by most radio operators as too close for reception on 28 MHz, although there is a chance of short skip Sporadic E propagation or backscatter.  Secondly I will be listening on 50.110 MHz for VK stations taking advantage of Sporadic E.

Booroomba Rocks is a formation of three distinct granite knolls with a total footprint bigger than three MCGs, Melbourne Cricket Grounds combined.  The highest point above sea level at 1382 m ASL is marked by a stone cairn on the south knoll.  For the ease of identification lets call the highest point Knoll 1 (southern end), Knoll 2 in the center and Knoll 3 at the northern end.

On the horizon Booroomba Rocks Namadgi National Park

Booroomba Rocks VK1/AC-026

Booroomba Rocks VK1/AC-026 (photo taken in 2013)

How do you get to the rock?

The ascent starts from the Booroomba Rock car park following a well defined walking track which starts out easy but changes rapidly to a steep rocky stair climb, climbing 240 metres over 2.2 km taking 75 minutes.

Booroomba Rocks GPS track log

Booroomba Rocks GPS track log

Booroomba Rocks track profile

Booroomba Rocks track profile, Knoll 2 is the hump at 1.5 km

Section of the track below Knoll 2

sample of the track to the middle knoll - stair climb 101

section of the track leading to a saddle between Knoll 2 and Knoll 3 – stair climb 101

Two wild flowers observed during the ascent

wild flower

wild flower

wild flower

wild flower

Standing at the highest point on Knoll 2 looking south across to Knoll 1, my destination.  🙂

view from the center knoll to the summit of Booroomba Rocks

view of the summit of Booroomba Rocks from Knoll 2 or the center Knoll.

From the saddle or lowest point between Knoll 2 and Knoll 3, the track is marked by a variety of stone cairns.  Below is a sample of three cairns.

large stone cairn guides

stepping onto a massive granite slab forming Knoll 1 – a stone cairn marks the route ahead

small stone cairn

small stone cairn on Knoll 2

stone cairn with direction markers

stone cairn with directional markers indicating the direction to the next cairn

At Knoll 1 a dry rock pool, a good thunderstorm combined with a heavy downpour will fill the rock pool.  Water drains from higher points into a series of rock pools formed on shelf 20 meters below the summit.

Rock Pool (Dec 15)

Rock Pool at Knoll 1 (December 2015)

Same rock pool in August 2015.  August was a wet month in Canberra.  Each pool was teeming with tadpoles.

Rock Pool (Aug 15)

Same Rock Pool in August 2015.

Rock Pools at Booroomba Rocks (August 2015)

Rock Pools at Booroomba Rocks supporting local wildlife (August 2015)

Standing on Knoll 1 (summit) looking back (north) to Knoll 2

view of the center knoll from the summit

view of Knoll 2 from the summit Knoll 1.  Behind Knoll 2 is Knoll 3 at the northern end.

360 panoramic view – no obstacles therefore no additional attenuation of radio signals

view north to Canberra and beyond

view north to Canberra and beyond

Equipment carried to the summit:

VK1AD SOTA shack on Booroomba Rocks

VK1AD SOTA shack adjacent to Booroomba Rocks stone cairn

10m J-Pole Antenna

10m J-Pole Antenna kindly donated by Herbert OE9HRV

VK1AD SOTA shack at the summit of Booroomba Rocks

VK1AD SOTA shack at the summit of Booroomba Rocks.  Left to right DX-Wire telescopic fiberglass pole supporting a 10m J-Pole antenna, stone cairn (highest point @1382 metres ASL) supporting a 6m 1/2 wave vertical coaxial dipole fixed to a 5 metre elchepo telescopic fiberglass pole.

SOTA Activation

Possible local summit to summit contacts: Matt VK1MA has been at Mt Ginini VK1/AC-008 overnight, Andrew VK1DA/2 will be at Spring Hill VK2/ST-036 and Adan is planning an activation of One Tree Hill VK1/AC-035.  Further afield in Victoria Tony VK3CAT has plans to activate VK3/VC-037 (unnamed) and Gerard VK2IO operating in Sydney has plans to activate VK2/SY-001 Canoelands.

Started the SOTA activation 2130 UTC (8:30 am local) on 28.485 MHz working 18 chasers in 45 minutes.  This first session on 10m netted two S2S contacts (Adan VK1FJAW at One Tree Hill and Matt VK1MA at Mt Ginini) plus 8 unique callsigns for the 10m challenge.

Time Call Band Mode Notes
21:28z VK1ATP 28MHz SSB Paul S58 R58
21:30z VK1FJAW/P 28MHz SSB Adan S2S VK1/AC-035 S59 R59
21:40z VK1VIC/P 28MHz SSB Tony S59 R59
21:41z VK1WX 28MHz SSB Amanda S59 R59
21:46z VK2XZ 28MHz SSB S59 R59
21:47z VK1MA/P 28MHz SSB Matt S2S VK1/AC-008 S59 R59
21:49z VK1AMG/M 28MHz SSB Brett S59 R59
21:52z VK1MT 28MHz SSB Matt S59 R59
21:54z VK4DI 28MHz SSB S59 R59
21:55z VK4KW 28MHz SSB S59 R59
21:57z VK1XP 28MHz SSB Peter S59 R58
21:58z VK1NS 28MHz SSB Nick S59 R59
22:02z VK5PAS 28MHz SSB Paul S55 R51
22:04z VK2FSAV 28MHz SSB Brett S58 R53
22:06z VK1XYZ 28MHz SSB Michael S59 R59
22:08z VK2HJ 28MHz SSB Dom S59 R58
22:13z VK1KW 28MHz SSB Rob S59 R59
22:15z VK5FDLK 28MHz SSB Mike S59 R51

Time to try 6m.  Moved to 50.149 after hearing Matt VK1MA at Mt Ginini working Jim VK3II near Philip Island (Victoria).  Matt called me in and to my surprise I worked Jim using the 6m Flowerpot antenna @ 25 watts.  My signal to Jim was weak, I suspect Jim’s massive antenna array was doing the heaving lifting.  Signal reports were Jim 5-1 myself 4-1.  🙂

After the excitement of working Jim and gaining a new unique on 6m, Matt and I discussed a tag-team approach to working other stations on 6m.  Next on 6m was Rod VK2TWR 5-5 each way, then another surprise, Glenn VK3YY was calling me from his home QTH in the outer south-east suburbs of Melbourne.  Glenn suggested my signal had the characteristic of backscatter, although my signal was weak the signal level was constant and readable. Glenn and I successfully exchanged signal reports, Glenn 5-1 and myself 4-1.  I called Matt VK1MA in unfortunately Matt was experiencing a local source of interference (QRM) and didn’t hear Glenn even though I considered Matt’s location and height ASL to be superior to my position at Booroomba Rocks.  20 minutes passed by with no contacts before Gregg VK1AI in Canberra called in for a chat.  After Gregg a nice Sporadic E opening provided propagation north to Far North Queensland (FNQ).  The Europe equivalent is Budapest to London spanning 4 countries.  In order, Matt and I worked Bruce VK4BOO, John VK4JMC, John VK4FNQ at Charters Towers 1740 km due north and a special event station VI4ANZAC operator Glenn.  Signal reports at Booroomba Rocks were 5-9, each of the VK4s reported my signal between 5-5 to 5-9.    During the 6m session I made a quick dash to 10m to work Andrew VK1DA/2 at Spring Hill, while on 10m Andrew offered me a quick signal report exchange with Brett VK2VW, thanks Andrew.

6m Contacts prior to UTC midnight.  5 new callsigns for the 6m Challenge  🙂

Time Call Band Mode Notes
22:26z VK3II 50MHz SSB Jim S51 R41
22:27z VK2TWR 50MHz SSB Rod S55 R54
22:29z VK1MA/P 50MHz SSB Matt S2S VK1/AC-008 S59 R59
22:32z VK3YY 50MHz SSB Glenn S51 R41 backscatter to Melbourne
22:51z VK1AI 50MHz SSB Gregg S59 R59
22:54z VK4BOO 50MHz SSB Bruce S56 R56
23:04z VK1DA/2 28MHz SSB Andrew S2S VK2/ST-036 S59 R59
23:04z VK2VW 28MHz SSB Brett S55 R53
23:07z VK4JMC 50MHz SSB John S59 R59
23:10z VK4FNQ 50MHz SSB John S59 R56  Charters Towers 1740 km
23:15z VI4ANZAC 50MHz SSB Glenn Special Event station S59 R55

As expected the Sporadic E on 6m didn’t last so back to 10m to seek out new callsigns.  As luck would have it, at 23:35 UTC 10m opened to VK5 (1100 km) and VK6 (3500 km) and although not classified as a DX contact VK6NC is further west from Canberra than London is from Moscow.

Stations worked before UTC midnight were Steve VK6NC, Nev VK5WG and Ian VK5IS.  Post UTC chasers were Nev VK5WG, Ian VK5IS and for a 4th S2S Matt VK1MA/P nearby at Mt Ginini.

My time at Booroomba Rocks is coming to end, a last ditch effort netted no additional callsigns on 10m.  In the meantime SOTA Goat (iPhone app) bleated after Tony VK3CAT posted a spot on 10m CW.  I knew I had no chance of working Tony on 10m SSB (voice), so I posted a spot for 10.130 MHz SSB (30m band).  On 30m chasers were Steve VK7CW, Peter VK3PF, Tony VK3CAT making a quick band change at the press of a button on his KX3 combined with a Doublet Antenna.  Tony is activating an unnamed summit VK3/VC-037 in Victoria’s central region.  Last but no least on 30m was Adam VK2YK near Newcastle in the state of NSW.

On 40m, 7.090 MHz chasers were limited to Ray VK3YAR, Ken VK3UH, Peter VK3FPSR, Adam VK2YK and Brett VK2VW.   Adan VK1FJAW/P had moved summits to Spring Hill operating with Andrew VK1DA/2.  Last and final contacts on 10m were Andrew VK1DA/2 and Adan VK1FJAW/2 plus a new unique Tim VK4VI/P.

Gerard VK2IO and I spent five minutes listening for each other on 28.445 MHz, unfortunately the 10m opening didn’t favour our locations both well inside the propagation skip zone.

Time Call Band Mode Notes
00:03z VK5WG 28MHz SSB Nev S51 R51
00:04z VK5IS 28MHz SSB Ian S51 R51
00:05z VK1MA/P 28MHz SSB Matt S2S VK1/AC-008 S59 R59
00:11z VK7CW 10MHz SSB Steve S59 R59
00:13z VK3PF 10MHz SSB Peter S59 R55
00:14z VK3CAT/P 10MHz SSB Tony S2S VK3/VC-037 S59 R59
00:18z VK2YK 10MHz SSB Adam S59 R53
00:28z VK3YAR 7MHz SSB Ray S59 R56
00:30z VK3UH 7MHz SSB Ken S58 R53
00:31z VK3FPSR 7MHz SSB Peter S59 R58
00:32z VK2YK 7MHz SSB Adam S58 R45
00:34z VK2VW 7MHz SSB Brett S58 R55
00:38z VK1DA/2 28MHz SSB Andrew S2S VK2/ST-036 S59 R59
00:47z VK4VI/P 28MHz SSB Tim S59 R59
00:53z VK1FJAW/2 28MHz SSB Adan S2S VK2/ST-036 S59 R59

Summary.   3.5 hours at Booroomba Rocks netted 19 unique callsigns, exhausting one 16 volt 4S 5Ah LiPo and a 4S 3.6 Ah LiPo.  Both 16 volt LiPo batteries are regulated by passing the current through a 30A Bridge Rectifier.  The silicon diode’s forward bias drops the battery potential by 0.7 volts per diode.  With 2 active diodes in the circuit the voltage drop is 1.4 volts from 16.8 volts (when fully charged) to 15.4 volts.  15.4 volts is within the 15% tolerance of the Yaesu FT-857D operating range centered at 13.8 volts.  Below is a photo taken at Mt Taylor.  In the photo the DC power-train in order is:  16 volt 4S 3.6 Ah LiPo > Watts Up meter > Bridge Rectifier > In-line Fuse Block > Radio FT-857D.  The fuse block should be inserted before the Bridge Rectifier not after.  All DC plugs are 30A Anderson PowerPoles.    When the LiPo operating voltage drops to 15.4 (as indicated on the Watts Up meter) I remove the Bridge Rectifier from the supply train.  At 13.2 volts, 3.3 volts per cell the 4S LiPo is considered to be exhausted and ready for recharging.

16 volt LiPo regulated by a 30A Bridge Rectifier

16 volt LiPo regulated by a 30A Bridge Rectifier

Reference / Links
Herbert OE9HRV (n.d) In Flickr from  (accessed 23 Dec 15)


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