[aprssig] CNSP-18 now 30m HF APRS transmitter

Matti Aarnio oh2mqk at sral.fi
Wed Dec 5 03:48:20 EST 2012

On Wed, Dec 05, 2012 at 08:23:14AM +0000, Chris Moulding wrote:
> About 4 years ago I made a 10W transmitter for 30m with AX.25
> frequency shift keying of a crystal oscillator.
> It worked really well.
> I'd forgotten about it until I spotted your posts. I'll take look at
> it again. It would be relatively easy to add it to an APRS TNC Digi
> Tracker to make a self-contained HF APRS tracker with it's own GPS
> receiver.

Additional experience note on HF from a balloon:

You need to have a dipole antenna - an end-fed long wire hanging
below means your payload is close to voltage maximum of the antenna
and can disturb itself rather seriously.

A 30m band antenna is 7.5m long wire both up and down - and you can
use upper wire as a structural member (rope) of the system.
Put the parachute above the wire, and a small weight at the hanging one.

For electrical budget: QRP for the win...
(Tx every 10 minutes, not once a minute.)

> 73,
> Chris, G4HYG

73 de Matti, OH2MQK

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