[aprssig] TNC-x

[Rick Stoneking]

On my TNC-X it is an open collector NPN driven by an I/O pin on the PIC
Micro.
Rick

----- Original Message ----- 
From: "Bob Bruninga" <bruninga at usna.edu>
To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Sent: Sunday, September 19, 2004 9:08 AM
Subject: Re: [aprssig] TNC-x


> I havent seen a TNC-x, but is the PTT an open collector NPN or
> just an I/O pin on the chip?
>
> Bob
> On Sat, 18 Sep 2004, Wes Johnston wrote:
>
> > I have a first run TNC-x hooked to a yaesu vx150 HT.  I added a 1uF cap
> > in line with the audio since it didn't have one on that revision level
> > and that was what a kpc3 uses.  Since it was an HT, I bridged the PTT
> > over to the audio with a 2.2k resistor.  All is fine so far.... when the
> > tnc keys up the radio, it locks in transmit mode.  Having seen this
> > problem before with tiny traks, I put a .1uF ceramic disc cap across the
> > PTT to ground inside the TNC-x housing.  The housing is a cast aluminum
> > hammond box.  Still, it locks in transmit.  I hooked it to another
> > radio, a radio shack htx252 which also uses the same 2.2k ptt setup
> > (just like an HT).  It too locks on TX.
> >
> > The DB9 I'm using for a radio data plug is wired the same as a kpc3 (so
> > I can use the same cables), it is mounted to the metal box.  The tnc is
> > grounded to the box by the three mounting screws in the corners of the
> > PCB.  There are no wires exposed except for the radio cable and the USB
> > cable.  It's actually a very neat (ie clean) setup.
> >
> > Any other suggestions?
> >
> > Wes
> >
> > _______________________________________________
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> >
>
> de WB4APR at amsat.org, Bob
>
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>
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