[OZAPRS] Low cost APRS HF Modem + Transmitter

[Andrew Rich (VK4TEC)]

Great idea !

----- Original Message -----
From: "Richter, Mike W" <Michael.Richter at team.telstra.com>
To: <ozaprs at marconi.ics.mq.edu.au>
Sent: Tuesday, November 18, 2003 1:31 AM
Subject: [OZAPRS] Low cost APRS HF Modem + Transmitter


Byon has indicated he may able to start work soon on the Encoder and Modem
for a low cost HF Transmitter.

Does anyone know of a design for a HF CW Transmitter that could be adapted
for a simple, compact, low-cost high-power APRS HF Transmitter. Just FSK
the
crystal.

Battery requirements would also be minimal because the Duty Cycle is so
low
and there would be NO standby current between transmissions. Although you
would need REALLY big capacitors to supply the transmit current for the
several seconds of the transmission if you wanted to use a "small" battery
that couldn't provide the whole Tx current.

Even if you did want to use Receiver to monitor packets, you could use a
compact scanner such as VR500 or THF6 (if they are stable enough on HF SSB
????). As a minimum they could be  used for Carrier detection to minimise
Packet Collisions.

Mike VK2BMM


-----Original Message-----
From: Bob Bruninga [mailto:bruninga at u]
Sent: Tuesday, 18 November 2003 12:32 am
To: Byon Garrabrant
Cc: Mike Richter; Robert Bruninga
Subject: Re: TinyTrak for HF APRS at 300 baud


> > There seems to be quite a bit of interest in using the TinyTrack for
> > 300baud HF APRS - especially down south for some reason.

This will take off like MAD when someone builds a 5 transistor 100W
transmitter the size of a cigarette pack. (yes it can be done easily
without a heat sink, because for APRS, the duty cycle is so tiny.  It
only has to disapate heat for 3 seconds every 5 to 10 minutes or so..

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