18 April 2015

06 SOTA Activation: Mt. Stromlo VK1/AC-043

Mt. Stromlo VK1/AC-043 (17 April 2015)

I had a few days of leave up my sleeve and decided to go for a few activations. Mount Stromlo is the site of the ANU's Research School of Astronomy & Astrophysics which lost all their telescopes in the 2003 Canberra bush fire. A new main building and telescopes have since been put up. Mount Stromlo is also a part of the Mount Stromlo Forest Park, used for mountain biking and other outdoor sports.

Mount Stromlo Rd. becomes Oddie Way, which terminates at this car park.

Taking advice from Andrew VK1DA about RF noise at the Trig Point, I walked further up the hill, past the Trig Point to the north, first going down a footpath and then up the other side on a dirt road. There I found a perfect spot to set-up.

Go past the Trig Point, up the dirt road on the next hill.

This was only my second solo activation but I was already finding a good, efficient unpacking and set-up rhythm. I could see a water pipe sticking up out of the ground but decided not to use it as anchor point for the squid pole. Instead I wanted to try a 3D-printed guy rope sleeve that slips over the squid pole, coming to a rest just above the junction between the lowest and second telescopic segment. Have a look at the red object around the squid pole in the picture below. I originally wanted to have the guy set-up slightly higher, around 2 or 3 meters from the ground but heard from Andrew VK1DA that this lower mounting point works really well for Andrew VK1NAM. I tried it and I like it. To simplify setting up the pole, ideally one would want the squid pole inserted into a fishing rod holder, or something that fixes the base to one spot.  I have come across the perfect rod holders from K-Mart, for $5.

Ham Shack on Mount Stromlo with the Antenna Domes and Brindabella Mountains in the background.
On the squid pole, I had the 40 meter link dipole antenna at the top and the 2 meter Fold-up Moxon mounted horizontally about 4 meter from the ground. The Moxon's red central doughnut slips over the squid pole and slides all the way down until the doughnut's inner diameter matches the squid pole's outer diameter.

2 Meter Fold-up Moxon

The link dipole is simply two pieces of wire, each one quarter wave length of the 40 meter band. In other words, they are approximately 10 meters apiece, and jointly 20 meters long. The wires have been chopped up into 5 pieces, each piece terminated in a RCA plug. By connecting all the plugs, I have a dipole antenna that is resonant on 40 meters (7.1 MHz). By decoupling the outer two RCA plugs, I have an antenna that is resonant on the 20 meter band, and so on, all they way up to the 6 meter band. To switch frequencies, all I need to do is to pull the squid pole down and change the configuration of connected RCA plugs. This takes no more than 2-3 minutes.

The dipole's two wire elements (with RCA plugs) are joined in the middle, not directly to each other, but to a BNC Antenna connector, so that the one connects to the centre conductor of the BNC connector and the other to the outer conductor.

The dipole and Moxon are fed by stock RG58 50Ohm coaxial cable, terminated in BNC connectors.

How to Get There

Access to the summit is pretty straightforward. Mount Stromlo Road turns out of Cotter Road and can be followed to to a car park that is about 50 meters from the summit.

Mount Stromlo Road turns out of Cotter Road

Special Permissions or Arrangements

None required. Access is via a public road, but according to the VKSOTA site, the road to the summit is closed at night. Reference: VKSOTA.

Summit Information

Mount Stromlo’s summit is 782 meters above mean sea level and it is worth 1 SOTA activation point. Its Maidenhead locator is QF44mq. The summit is open with great views all round. There are a few Mountain Bike tracks, so take care when you set up that you don't run your dipole or guy ropes across a track. The summit is exposed so the wind and sun can be a nuisance.


I finally settled my feud with Rucksack Radio Tool and it logged me into Sotawatch at last, so I could spot myself. In fairness though, I was using the wrong username all the time. My bad, not RRTs!

It was a great start to the morning, with 30+ contacts. This was off course helped along by the activation time that coincided with the UTC rollover from 8 to 9 April, allowing Chasers to gain points for the summit on the 8th and the 9th of April.

Useful Links

 SOTAWATCH Summit Information: http://www.sotawatch.org/summits.php?summit=VK1/AC-043


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