[OZAPRS] Trip observations ...

[Terry Neumann]

G'day Oz-aprs's,

Here are some observations on our recent trip to VK1 and nearby areas.   I
would like to start by thanking all of those who assisted in the
experiment by enabling my sigs to get onto the net through their station
facilities.   APRS - like packet - is dependent upon the generosity of
other amateurs in making their equipment available.  Thanks again to each
and every one of you.

I used a combination of 30 metres and 2 metres for the entire trip - 30
metres was used except where I anticipated that 2 metre digi's or gates
were likely to be available.   There were also brief excursions onto 20
metres to QSO with ZL friends who aren't able to operate phone on 30
metres.   The Tiny Track option of allowing two sets of parameters allows
easy switching from one band to the other - important to remember to QSY
at the same time of course.   

I was able to have a couple of  phone contacts during the trip which were
very much appreciated.   I also heard one call on 2 metres in Mildura
which I think may have been for me on the trip over, but I was somewhat
involved in driving and navigating at the time.  When I was free to
respond the caller had apparently gone.   Apologies for that, it would
have been nice to catch up.   Thanks also to Tony for his encouraging SMS
- alas the opportunity to reply took a couple of hours for a favourable
cell to come over the horizon. 

I was fascinated by the strength of the beacons on 30 metres at times.
Even with the IC-706 preamp out, the signals were strong enough to break
through a fairly high squelch setting.   It was interesting to see that
the last beacon yesterday onto FindU was almost exactly on sunset at my
then location at Renmark.   It was received by one of the ZL gate stations
- fascinating.   I stayed on 30 metres for the balance of the trip but
apparently nothing further was received. 

I'm delighted with the results of HF APRS on 30 metres, and I look forward
to an opportunity to try it out again.       

The equipment I used may be of interest:

1) Garmin GPS II+

2) Tiny Track 3.11 - built into a diecast box with filtering on all signal
leads, and some additional mods suggested by Andrew (VK5EX).   The GPS
input is also "split" with 1k resistors to allow a Rob Keskull Data Logger
to record the trip.  It also permits a second dedicated VHF only TT for
future dual band continuous operation.   

3) Icom IC-706 mark 1 - The TT is fed to the accessory socket on the back
of the 706.   The output of the TT3 was "boosted" above the standard TT3
by padding R5 with a 100 k resistor as described in the manual in order to
obtain sufficient drive to get the 706 to a useful power level on HF.   In
my experience the accessory socket requires a higher signal level to drive
the rig to a useful output than the standard mike socket(s).

I elected to settle on 50 watts as the desirable figure on HF.   This
gives less than desirable deviation on the 2 metre band, but it's enough.
The rig feeds a dedicated LDG Z-100 automatic ATU which is controlled by
the tune function on the 706 panel.      
4) The HF antenna used is one of my home-brew top load devices mounted on
the rear of the Magna - a limited description of the mounting details can
be seen at:    http://www.rbe.net.au/~tfn/Amateur/Magna/Magna.html
<http://www.rbe.net.au/%7Etfn/Amateur/Magna/Magna.html>   

5) The VHF antenna is a 1/4 wave on a magnetic base on the RH front boot
lid of the Magna - nothing  fancy here.  It would be nice to have it
somewhere else, but the options are limited.  

  Issues to work through in the future are:

1) Serious noise on 30 metres from the radiator fans on the Magna - they
come on with the air conditioner.

2) Heavy swamping of the broadcast radio in the Magna during TX of packets
- especially on the FM band, when on VHF.  This problem is also evident in
APRS installation in the farm ute.   This problem has already been
explored in considerable detail in both vehicles with no certain cure so
far.    (We both like our ABC classic FM).         

Thank you again to all who assisted with their patience and encouragement
both prior to and during the exercise.  It was a lot of fun.

Finally a cautionary note:

The return trip was around 1200 kilometres - a big one for a one day
effort, even with two drivers.  The last section of the trip was through
known kangaroo country, at night, and the blighters were out in quantity
in some hot spots.   This is not a lot of fun after 11 hours and some
1,000 km already on the road.

While I am have nearly 44 years of country driving behind me,  I
discovered that reducing speed from the daytime legal levels to around 90
kph may still not be quite enough to allow a safe stopping distance in the
worst case.

Current TV commercials about the big difference in stopping distances at
various speeds are soundly based.   

73
Terry 
VK5ATN
    

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