Results of a Group Propagation Test Between VK6AAL and VK2, VK3, VK4 on Friday 15 September 2006
This was a most interesting exercise by combining the messaging and group activity of VK2,3,4 it enabled a very good assesment of the propagation path to VK6. It is quite obvious that VK6 has a marked disadvantage on 40m and 80m and this was proven last night on SSTV.
SSTV is a great tool for proagation testing and antenna tests combined with the SSTV Webcams you get to see the Whole Picture....
80 m is practical from VK6 if both parties are using minimum antenna requirements of an 80m Dipole at 15m facing North / South or oriented for the path.
It is really not practical with trapped Verticals to Dipole the combined polarisation effects are a breaking point for SSTV.
If both parties where running verticals with a complete ground mat in clear space this might be different but in suburbia this is not very practical.
40 m is very effective as both antennas tended to be more efficient even my Windom approaches optimum height for 40 m and this again was proven with VK3HJV pictures being almost perfect on 40m and satisfactory on 80m using a Dipole and 100w.
The largest problem VK6 has is the orientation of antennas in the East where dipoles are used and configured for working North South, the test I ran on the Dipole for Europe on 40m here showed a 6db drop on recieve and similar on Tx to the East coast over the Windom that is optimised to be directional for the east coast. Even though the Inverted V should have more Vertical content for both directions than the Windom it was still 6db down to VK2 using a vertical for recieving.
For VK6 stations an increase in power at this end will assist 80 m Tx to the East but do nothing for reception, so for SSTV this is pointless but in the RD contest it would make a significant difference in the result as it is hard to compete to be heard in group activities, a large wire array at the local club station would be a better result both ways.
In the end there is no substitute for lots of wire in the low bands and I wish I had my old location in Newman with 110 ft tower on a massive hill but at least we don't have the QRN of the North West where static crashes on 80 m are at least 10db over 9 most of the time. We had ideal conditions for the tests from VK6AAL no wind and static crashes at 5/5 with ocassional crashes to 5/9 on 80m
Thanks again guys and girls a great effort by all 73 for now see you back on the Magic Band 14.236 where we can all hear VK4