[ao16aprs] Re: ao16aprs digest: September 20, 1999

["KF4FDJ (Mike in Fort Myers)" <seven77@gate.net>]

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Just got back from the movies with the kids.  They called off school,
again, because of tropical storm Harvey.  I don't know what happened,
but the skies are blue and the birds are singing.

In case you didn't get it yet, here's the wiring diagram.

73, Mike

Jeff Griffin wrote:
> 
> Good morning everyone. I will have the pacgate up today also. I'm having a
> problem with my lower back and have been out of work for several days. I'm
> glad to have something to do, I will monitor most of the passes. Does anyone
> have a schematic for the tnc-2 Manchester encoding mod? If so please mail it
> to me.
> 
> 73 Jeff kb2wqm
> 
> ---
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MOBILE STATION:  A mobile station consists of nothing more than a typical 
2 meter FM radio and a modified TAPR-2 compatible TNC as shown in figure
1.  Optional accessories are a GPS for moving position reports, and a 
laptop for modifying the status message.  Most modern TNC's will accept 
the GPS data directly and will transmit the data in a timed packet burst.
There are even tiny handheld TNC's available that include front panel
switches for selecting 1 of 7 pre-canned status messages without needing
a laptop to change the status report.  The modifications to the TAPR-2
TNC are to simply EXclusive OR the transmit data with its 1200 Hz clock
and to filter the result to the Mic input of the radio.  The following
circuit will do this with nothing but an 89 cent standard 7400 quad
2 input NAND gate connected to the two points shown.

  19-20 J5            |\     
  TXD ---*------------| |0--*
         |         *--|/    |   
         *---|\    |        *---|\      
             | |0--|        *---| |0--*--/\/\/\--*-------*       
         *---|/    |  |\    |   |/               |       \ 1k
         |         *--| |0--*                   ===.2uF  / <----*> To Mic
  TXC ---*------------|/                         |       \
  U10A pin 6                                     |       /
                                               -----   -----
                                               /////   /////

The pin numbers shown are for a PacComm TINY-2.