Expense and complexity is the barrier.
30 meter SSB transceiver alone costs more than the entire VHF solution does.
At 300 baud, tuning is critical as well.
AX.25 on 2-m FM is "plug, play and forget".
Ev, W2EV
----- Original Message ----
From: David Erickson <erickson+vhf@mentis.org>
To: vhfcontesting@contesting.com
Sent: Thursday, December 27, 2007 7:29:52 AM
Subject: Re: [VHFcontesting] Use of APRS in the Rover
Why not beacon APRS 300 baud packet on HF? A quick google search will
get
you some good frequencies and bands. Plus Depending on band conditions
during the contest you'll be more likely to be heard by someone during
most of the rove.
73's
Dave W3DIO
http://www.w3dio.org/
> ----- Original Message ----
> From: Dan Evans <dan.evans@insightbb.com>
>
>
>
> So how bad do you think the APRS signal is going to be for the 2m SSB
> station? ---------------------------
>
>
> The frequency difference between 144.39 and 144.2 is only 190-kHz.
This
> is much too narrow for a filter of any sort. There are two general
> strategies to employ for APRS use in a rover:
>
> On the SSB side, use a transverter for SSB operation -- one with a
high
> dynamic range front. I use the SSB Electronics transverter on
2-meters,
> and the band is quiet within 5-kHz of a KW station only 8km from my
home
> (when they are active).
>
>
> On the APRS side, use low power (really! 300mW may be ok), poor
antenna
> (really!) and separate the antenna from the SSB antenna by as great
of a
> distance as possible. Remember, all you need to do is be heard by a
> digipeater and you'll be repeated for others to hear. You'll already
be
> on a hilltop or knoll, so probably LOS to a digipeater. Alternately,
> consider powering-on the APRS system only when the QSO rate is low,
or
> while in-transit and not on SSB, etc.
>
> As with so many other things, there are many variations of these
> strategies that can be made to work, but this can give folks a few
ideas
> to digest.
>
> Regards,
> Ev, W2EV
>
>
> PS: The advice for APRS is *opposite* that of HamIM, where high power
and
> good antennas are the norm. Why the difference? HamIM takes place
on
> 147.585 (over 3-MHz away!), and is simplex in nature. A 70-watt 1/2
> second TX is barely noticed on the 2m SSB transceiver.
>
>
>
>
>
>
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