[aprssig] 433 MHz operation

Scott Miller scott at opentrac.org
Wed Feb 15 15:43:52 CST 2012

They're frequency-agile so it's not so much a matter of pre-setting the 
frequency, but the reference crystal will control exactly what part of 
the band they can cover.

There's also a version of the transceiver that covers the whole 33 cm 
band (the US allocation anyway) and would be a drop-in replacement 
requiring only a couple of minor code tweaks to set the frequency right.

I figure I should be able to sell the transceivers themselves for not 
more than $20 each.  And my prototype tracker, less antenna and battery, 
weighs 30 grams so I'm eager to try it out on a balloon.


On 2/15/2012 11:17 AM, Andre wrote:
> Op 15-2-2012 19:12, Scott Miller schreef:
>> Hi all,
>> I've been playing with some half-watt 70 cm data transceivers lately.
>> I'm currently testing at 434 MHz, and with the standard crystal they
>> should cover about 430 to 439 MHz. I'm not really familiar with the 70
>> cm band plan and figured I'd check here and see if people consider
>> that a reasonable part of the band to be working in.
> I asume you are looking for frequenties to pretune the radios to.
> Europe has a number of aprs frequenties on 70 cm because it's a very
> regionaly planned band.
> the first used 70cm aprs frequentie is 430.5125 but not every country
> has the full range so a seccond frequentie is sugested but websites are
> conflicting on what it is, I have seen 432.500 and 433.800
> At any rate never put it between 435 and 438 because that is sattelite
> usage.
> Also above 440 and below 430 is not usable in europe
> 73 Andre PE1RDW
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