Are you sure 433Mhz are covering indeed 30miles even LOS?
I've translated into Km and (if I didn't mistake ) it's about 48Km.
So what power (EIRP) has your transciever?

greetings,
Vasile

On 9/24/06, Art <KY1K@verizon.net> wrote:
> I need a very low cost wireless thermometer to cover 30 miles (near
> line of sight). I have a ham license, so I can legally boost the 433
> MHz part 5 wireless remote units that come with low cost Atomic
> Clocks that have facilities for monitoring temperatures from several
> wireless remote sending units (provided I can figure out how to key
> the transmitter to make it ID with my callsign).
>
> Needs to be low cost.
>
> It occurred to me that boosting one of these very low power
> transmitters and feeding it into a real antenna might piss off lots
> of nearby users tho, so I'd really prefer to roll my own system.
>
> Has anyone hacked into these wireless remote temperature sensors such
> as the Oregon Scientific THR138? Changing the frequency of the
> receiver and transmitter slightly (to move it off the commonly used
> 433 Mhz channels),  is probably practical.
>
> Thanks,
>
> Art
>
>
>
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