[aprssig] TNC-x

[Bob Bruninga]

Thanks.  Just checking.   It must have been RF rectificatiosn...

bob

On Sun, 19 Sep 2004, Wes Johnston wrote:

> It is open collector.  http://johnhansen.org/media/schematic.gif .   It
> is _now_ open collector with a .1uF cap from collector to ground. ;-)
>
> Wes
>
> Bob Bruninga wrote:
>
> >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
> >
> >PCsat WEB  page     http://www.ew.usna.edu/~bruninga/pcsat.html
> >ISS-APRS FAQ:       http://www.ew.usna.edu/~bruninga/iss-faq.html
> >CUBESAT Designs     http://www.ew.usna.edu/~bruninga/cubesat.html
> >APRS LIVE pages     http://www.ew.usna.edu/~bruninga/aprs.html
> >APRS SATELLITES     http://www.ew.usna.edu/~bruninga/astars.html
> >MIM/Mic-E/Mic-Lite  http://ssdl.stanford.edu/mims/
> >
> >
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> >
> >
> >
>
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de WB4APR at amsat.org, Bob

PCsat WEB  page     http://www.ew.usna.edu/~bruninga/pcsat.html
ISS-APRS FAQ:       http://www.ew.usna.edu/~bruninga/iss-faq.html
CUBESAT Designs     http://www.ew.usna.edu/~bruninga/cubesat.html
APRS LIVE pages     http://www.ew.usna.edu/~bruninga/aprs.html
APRS SATELLITES     http://www.ew.usna.edu/~bruninga/astars.html
MIM/Mic-E/Mic-Lite  http://ssdl.stanford.edu/mims/