Portable Operations of
VK3BJM – Part
II.
As mentioned on the
"Portable Operations of VK3BJM” page, western NSW isn't the only remote
area that I've attempted VHF, UHF and SHF contacts from, utilising Aircraft
Enhanced Propagation. One of my
favourite spots on the continent is the Flinders Ranges; it was an area that
held a fascination for me as a child. I
read about it, and admired the photos, but actually visiting the place didn't
occur until August 1989. That first
trip, of 8 days duration, was as near a perfect trip as I could have imagined;
and it was the first of many. In fact,
I've just about lost track of the number of times I've been back in the last
(gulp!) 21 years, but it is around 14 or 15 times.
And the last few have
incorporated some degree of radioactivity, sorry, radio activity...
The distance between the
southern Flinders Ranges and the eastern suburbs of Melbourne, at 900+ km, is
pushing right to the limit of what can be achieved via AEP using common or
garden-type passenger jets running regular routes at their peak altitudes (up
to 41,000 feet).
But the recent addition of
ADS-B receivers to the arsenal has pushed predicting when to expect
"openings" out of the realm of black magic, guesswork and good-old
"cross you fingers and hope".
For stations in the Greater
Melbourne / Central Victoria area, AEP opportunities come mainly via the flight
paths between Adelaide and Sydney, and to a lesser extent those between
Adelaide and Brisbane, and Sydney to Perth.
There are a couple of flight paths from Melbourne to SE Asia (Singapore,
Hong Kong, Indonesia) that have looked as though they could be usable, but to
date attempts using them have not borne fruit.
Some of these paths cannot be relied upon, as they pass over the Woomera
Rocket Testing Range in SA, and when testing is taking place the flights are
diverted well outside the area - changing the geometry of the AEP footprint
entirely.
So far, greater success (or
near success, perhaps) has been achieved with flight paths that cross the beam
alignments, rather than those that "fly along" them.
My first foray into the area
was as a sideshow to a four-day trip to the central Flinders Ranges area
(around Blinman) in June 2001. At this
stage, I was focussed on the trip rather than thinking about whether AEP had
potential; consequently contacts were made via bog-standard tropo-scatter down
to Adelaide, and unsuccessful attempts were made via Meteor Scatter with Ron,
VK3AFW, in Melbourne.
My second foray into the area
was an attempt to work from the southeastern corner of PF97 in April 2002. This time AEP was the focus, as my aim was
to attempt to use the Singapore-bound Boeing 747's of the QANTAS and Singapore
Airlines fleets, which flew northwest from Melbourne each afternoon. Again, this was a long weekend trip. The first location was not ideal; it was on
a ridge (good) just along from the Mount Edward Radio Terminal, between Manna
Hill and Yunta. The radio terminal was
source of a large paging signal just above 148 MHz, which caused severe
desensing to my receiver (bad). The
next day we looked elsewhere, and found a far quieter spot on the ridge
overlooking the ghost town of Waukaringa.
However, success back into Melbourne still proved elusive, despite
having at least one aircraft come up the route, passing overhead.
Ahh; to have had an ADS-B
receiver back then...
The next few years saw my focus shift into western NSW, as previously described. It wasn't until 2008 that I decided to take myself away for a few days, in order to try activating a couple of new grid locators (QF04 and PF98), and to meet a friend in Quorn - Peter Whellum, VK5ZPG. Peter had contacted me after the publication of my article about AEP in western NSW, with an aim to trying to make such contacts. One of the flight paths to SE Asia passes over Quorn, and Peter had observed the regular contrails overhead.
Being a local, Peter had a
few suggestions for operating sites.
One was Mount Arden, a few kilometres (well, 22) NNW of Quorn. At 813 metres ASL, it was a significant
mound of dirt. Peter contacted the
owners of the property on which Mount arden resides - Argadells station, owned
by Malcolm and Judy Juett - who kindly allowed me permission to camp up on the
mount overnight.
From my site on the ridge,
signals on 144 MHz were heard from David, VK3HZ in Melbourne, courtesy of a
conveniently located aircraft. Sadly,
the high local noise floor in Melbourne prevented David from hearing me. At that time my station was running about
150 watts into a 10 element DL6WU style Yagi.
I also operated from the
Stokes Hill Lookout, near Wilpena Pound, for one night before returning to
Victoria. Conditions were not so
favourable here, but the overall experience suggested a return for another go
was warranted.
An article fully describing
the trip appeared in "Amateur Radio" magazine in the December 2008
edition. With thanks to the editor for
permission, it is available here as a PDF for viewing.
After a year of preparation,
a return trip was made to Mount Arden in October 2009. Sadly, despite sizable improvements to my portable
station, the attempt to work back into Melbourne was once again thwarted by the
high local noise floor. Too many RF-filthy
gadgets in the suburbs these days...
The trip wasn't a complete
loss, by any means. Due to a
self-imposed single band focus, I tried incorporating some of the digital modes
available via the WSJT program in addition to SSB contacts. Contacts via meteor scatter and tropo
scatter, using FSK441 and JT65, were made to VK2, 3, 4 and 7, in addition to SSB
contacts to VK5.
Another article fully
describing this trip appeared in "Amateur Radio" magazine in the
January/February 2011 edition. Again
with thanks to the editor for permission, it is available here as a PDF for viewing.
The issue of high local noise
is of serious concern for weak signal operators. Signals from David VK3HZ were easily readable via AEP on both my
trips to Mount Arden, for more than enough time to have made a contact. David does run the VK legal limit power
output, but only has a single Yagi station; there is no enormous antenna array
at his place! But the AEP signals were
large enough that he could have been running 6 dB less output and I would have
still been able to hear him at a readable level. So, the path and propagation mode is potentially good enough to
support a 100-watt / single Yagi station.
The plethora of RF-noisy gadgets is the problem to overcome.
In a side note, not long
after my return from the 2008 trip, I worked Peter VK5ZPG via AEP, courtesy of
an aircraft I could track on my ADS-B receiver, flying from Sydney to
Adelaide. Whilst Peter can run 300
watts from his AM-17 PA, his antenna is again a single Yagi - a VK3ATN design -
mounted only about five metres above the ground, and two metres above the metal
roof of his house. Peter's station is
on a flat next to a creek just north of Quorn - he has very little altitude, and
the ranges around him to contend with.
Though I might have a large array, his is not a super-station! Having a low noise floor at both our station
locations makes these contacts possible.
A change in tactic may be
required for future trips to the edge of the AEP footprint, if stations in Melbourne
are to be worked...
And in appreciation of the
kind assistance provided by Malcolm and Judy Juett: have a look at their website, especially if
you are considering a trundle around the Flinders Ranges in the future!
A Google Earth view of the signal paths between myself and VK5ZPG (green line); and VK3HZ and my two portable operating sites at Mount Arden and Stokes Hill Lookout (yellow lines). The red circle highlights the area where the enhancement takes place. The pink lines are the high-level aircraft tracks, or routes.
Updated 25/5/2011
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