[aprssig] APRS and RF data modules
jdw at eng.uah.edu
Thu Apr 28 07:52:55 CDT 2005
On Apr 28, 2005, at 7:23 AM, Andrew Rich wrote:
> can u get just 2m tx ?
I haven't seen any. There is a 70cm ISM band that coincides with the
70cm ham band (at least in the US), and that's why we see these little
I've seen several variations - AM, FM, etc - on several different
frequencies: 315MHz, 433MHz, somewhere in the 900MHz range, and maybe
1.2GHz (I could be hallucinating that last one). I think these
correspond to ISM (Industrial, Scientific, Medical) device frequencies.
The only thing I've seen on 2m is the Ramsey Rocket beacon (almost as
much $$ as an HT) and a few fox transmitters that are as much or more
than an HT.
I'd think that a simple low power 2m transmitter, either crystal
controlled or even a direct synthesis DAC type arrangement would be
doable for fairly cheap, but I haven't seen one. I don't have the time
or experience to try it myself.
I have thought about building a circuit similar to the Ramsey. but add
support for a PIC so it would be a useful 2m tracking beacon. Maybe a
DC-DC converter, so the thing would run off a single 1.5V AA lithium?
It would need 3 or 5 volts for the PIC and 9 or 12 for the transmitter.
I think maxim has a beastie that does both. Yet another project for
my copious spare time...
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