[aprssig] Quick and dirty weather

Wes Johnston aprs at kd4rdb.com
Fri Apr 15 12:45:22 EDT 2005

Scott... why not put teh kpc3 into it's MUTE mode.... where it can
assert radio port pin 8 when carrier is detected?  If your kpc3 is not a
plus model, tap a wire from the CD LED to pin 8 on radio connnector. 
This can be used by the open tracker as a squelch indication.  Also,
they might both try to key the radio at the same time, so a diode OR
between the kpc3 PTT line and the MUTE line will cause the open tracker
to see kpc3's PTT as a busy signal too.  The kpc3 signals run open
collector and pull low to assert, so I'm willing to bet you'd need a
logic inverter for your open tracker's carrier detect circuit... but,
hey, I hear you are pretty close to the guy that wrote the open tracker,
so maybe you could convince him to invert the CD in software ;-)

This at least solves two of your three problems.


Scott Miller wrote:

>I've been running a 1-wire station off an OpenTracker off and on for a while
>at my house, testing out solar charging setups and such.  Decided I wanted
>to make it a permanent installation, but didn't want to devote another
>antenna, radio, and power supply to the effort.
>What I wound up doing was plugging a DB9 Y cable between the KPC-3 on my
>IGate and the radio cable.  Jumpered the KPC-3 for external power, clipped
>the PTT diodes on the tracker so it'd play nice, and plugged it in to the
>other side of the Y.  Now they both use the same radio, and the KPC-3 powers
>the OpenTracker without any extra wiring.  A few obvious deficiencies come
>to mind:
>1. No collision avoidance between the two
>2. OpenTracker can't run open squelch
>3. IGate can't hear the tracker
>Number 1 isn't a big deal, since they both transmit infrequently.  Number 2
>is annoying, but my IGate hears 99% of its traffic from a couple of WIDEs
>and they've got long enough TXDs and strong enough signals that running open
>squelch doesn't really help anything.  And as for number 3, it's running a
>single-hop path, so the IGate hears the packet as it comes back from the
>It's quick and dirty, but it's simple and it works.  Just a Y cable,
>OpenTracker, 1-wire cable, and weather sensor unit.  I don't think this is
>what Kantronics intended when they put in the external power jumper, but it
>Scott, N1VG
>aprssig mailing list
>aprssig at lists.tapr.org

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