[aprssig] HF APRS ?

Stephen H. Smith wa8lmf2 at aol.com
Fri Mar 11 10:11:58 EST 2016

On 3/10/2016 1:34 PM, Clay via aprssig wrote:
> Any one still left on the old 30mtr APRS freq.?
> Clay AA3JY
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I just finished a 4300-mile (6900 km) road trip to southwest Texas and New 
Mexico beaconing on 30m with both classic AX.25 packet and the newer 
APRS-over-MFSK16 mode generated by the "APRS Messenger" soundcard program.

I even had several two-way text conversations on 30M in the vast emptyness of 
far west Texas.   (Part of the reason for the trip was to visit the McDonald 
Observatory at Ft Davis, TX. While there I did an NPOTA activation of Ft Davis 
National Historic Park.)

You can see live 30M activity as heard off-the-air in central Michigan, on both 
modes, mapped on my HF UI-webserver at:

.   <http://WA8LMF.net/map>

This map shows what I am hearing off-the-air (not the Internet) with my 
homebrew magloop antenna, a Kenwood TS-50 and the UZ7HO Soundmodem soundcard 
software TNC.

(I was shocked how much MORE I hear off-the-air from my mobile while on the 
road at more southerly latitudes.   Michigan seems to be a black hole for 30M 
HF propagation. There seems to be some sort of magic hop "pipeline" between me 
and KB0WZI-11 in Branson, MO who I hear nearly 24/7.)

This year, for the NPOTA (National Parks On The Air) operations,  I have TWO 
Yaesu FT-857s in the car.  One is mounted in the trunk and dedicated to 30M 
APRS using a 30M Hamstick.  The other, up front, is on a screwdriver for 
simultaneous use on other bands for mobile SSTV "LIveCAM" operations.

A TinyTrak III set to 300 baud HF mode is connected to the 30M FT-857's mike 
jack, while my Panasonic Toughbook through a homebrew soundcard interface is 
connected to the 6-pin mini-DIN "data" port for the MFSK16 mode.  Since the 
customary operating frequencies of the two modes are only 400 Hz apart, both 
can be beaconed through the same passband of the SSB rig without retuning.   I 
even successfully get both modes side-by-side through a 500-Hz CW filter.

I have the primary mode of the TinyTrak set to beacon the usual red car icon 
while the secondary mode transmits the campsite/tent icon commonly used for 
Field Day and similar events with the comment field loaded with "NPOTA - 
National Parks On The Air!".  Enroute I beacon the primary mode. Once I am 
on-site and setup, I just flip the TT3 to the secondary mode.

As far as I know, the TinyTrak is the only device that can generate a Mic-E 
format packet on 300-baud 200-Hz shift HF packet.   The success rate being 
heard on HF was significantly greater for the Mic-E TinyTrak than the 
longer-format position packets generated by PC-based APRS applications.

The mobile whips are so narrowband, I didn't have the slightest problem with 70 
watt APRS beacons desensitizing the other rig on other bands (mostly 40, 20 and 
15 meters).  (The two antennas are only about 3 feet apart.  The screwdriver is 
hard-mounted in the middle of the trunk lid of my Jetta TDI, while the Hamstick 
is mounted on a Breedlove Mounts mini split-ball mount on the left-rear fender.)

I will be conducting further operations of this type later this year.....

Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

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