Nevada Space Grant
Max Transmitting Power: 5 W
This is one of Kenwood's handhelds we bought ours for
$360. We used to use this handheld as the primary communication
payload radio because it is capable of decoding an
APRS (Automatic Position Reporting System)
signal without additional hardware.
We also use this when we are looking for the balloon after it
has landed. These radios allow you to get a signal from the
balloon on the ground. In conjunction with a handheld GPS, you can
pinpoint the exact location of the payload.
This handheld is one of the few (if not the only) with a built in TNC (Terminal Node Controller). Having a built in TNC is not required for APRS communication but it saves you from having to use an external TNC module. This is more important for the handheld sent up with the balloon than any other radio since weight is an issue.
maximum of 5 Watts transmitting power.
Battery life of ~5 hrs when transmitting, full power at the .2 min interval.
It's heavy. There are lighter radios. There are cheaper radios, but they don't transmit at 5 Watt's and don't have built in TNC.
At $363 it's a little pricey. Another mobile with an external TNC might be cheaper if cost is an issue.
Limited to 136-174 MHz (2 m) on band A [not possible to put
Band A and B on 400-480 MHz (70 cm)
We also found that the Kenwood will not transmit APRS data if
the frequency has ANY activity. This is a problem if you are trying to
transmit on the national APRS frequency. At 100,000 feet, you pick up
everything within about 400 miles (radius), so the national APRS
frequency has nearly constant traffic (i.e. the Kenwood never
transmits). Another lesson learned the hard way. This is not a problem
if you are using a frequency other than national APRS (144.390).