Determining SOTA Activation Zones in Google Earth

The Flood Tool

Google Earth is a remarkable resource. It’s free, for starters! Google Earth is embedded with altitude data. As such, a programmer called Bernard Sterzback in Germany has come up with a clever .kmz extension file that can be installed, and used to access that embedded altitude data to show ‘flood’ maps, in order to show what land projects above a user-input elevation level.

This is useful for determining the ‘within 25m of the summit’ Activation Zone for SOTA, as well as for hillwakers in determining likely paths and ridges, and the widths of such ridges.

To use the tool, first you will need to download this .kmz file link – KMZ Flood Tool for Google Earth

When it has downloaded, run it, and it will associate itself with Google Earth automatically.

Next, open Google Earth and head to a point of interest. I’ll use a SOTA summit – VK2/CW-050 – Caloma Trig Point for this example.

Caloma Trig

Next thing we need to do is determine the elevation of this summit. We can either click on the Google Earth placemarker, or move the mouse cursor to that point and read the elevation off the info bar at the bottom of the screen. Make a note of the summit altitude.



In this case, the reported elevations are pretty close, but I’ll go with the ‘official’ SOTA elevation of 774m.

Next, looking in the ‘Places’ collapsible dropdown on the left hand side of the Google Earth window, you should see your new ‘Flood’ tool you installed. Hover over it with the mouse, click the right mouse button, then left click ‘Properties’



In the window that opens, you can now edit the ‘Link’ data, which is the flood level you want to set to view. In my case, I want to see what area of land is available within 25m of the summit, so I edit the number to become 749 (ie. 25m less than 774). You must leave the ampersand ‘&’ symbol in at the end.


Then, click the [OK] button.

Now, you can enable the Flood Tool by clicking its check box, and the area will be ‘flooded’ to the level you just set, showing only the land remaining from 25m below the summit, to the summit. This is the SOTA Activation Zone. Easy, wasn’t it?! Once you’ve done it a few times, it becomes quite intuitive.


To clear the Flooded area, simply un-check the Flood tool.

See you on the summits, within the calculated Activation Zones!


VK2/CT-043 SOTA Activation

SOTA Activiation No.1 – Mount Tomah VK2/CT-043.

The weather forecast looked good. The gear was packed the day before, comprising my FT817 with external 4S LiPo, Voltage regulator, electrical power ‘Watts Up’ meter, tiny MS2 straight Morse key, 12m Spiderbeam pole shortened to 8m, and my PAR End Fedz 40/20/10 antenna. And a peg hammer!

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The radio case. (Hopefully) everything I need.

The journey to Mt. Tomah was uneventful. Not much traffic around at 7am on a Sunday! On arrival at the site, it was quite chilly – around 6°C. Fortunately I’d brought a Thermos flask of white hot chocolate to warm up with. A quick descent off the summit with the gear out of the activation zone and back to qualify. It was disappointing to see how much rubbish had been dumped down the slope. This place would be a good candidate for ‘Clean Up Australia Day’.

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Burnt out sofa frame antenna support

The pole was zip-tied to a convenient frame of a burnt-out sofa (yes, unfortunately true!), and the antenna was pegged at the far end, and a short coax run attached. I started operation on Saturday (UTC time). Spotting myself via Sota Spotter then calling CQ resulted in a run of contacts, quickly making the 4 required contacts, and going on to make many more, both before and after the UTC clock roll-over.

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Operating on 40m CW. Note the tiny MS2 Morse Key.

All my operation was on 40m. The band was in quite good shape, but with some deep QSB at points. Most operation was SSB, but with a bit of CW thrown in too. I’m glad I decided to bring the key in the end.

Calling CQ and VK4RF (Rick) replies, from Kallangur, Qld

A total of 35 QSO’s, and 9 Summit to Summit (S2S) QSO’s for 7 unique summits. Quite a productive mission! I wrapped up around midday local as I needed to get home. A shame I couldn’t stay longer and catch 20m opening for some DX.

Log for Saturday 29 Aug 2015 (UTC)
Log for Sunday 30 Aug 2015 (UTC)

Thanks to everyone for the QSO’s, and to those who activated other summits. See you next time! 73 – Rob