[aprssig] TNC Zip-Lan for training

Stephen H. Smith wa8lmf2 at aol.com
Tue Oct 6 21:13:18 EDT 2009

Tyler Griffiths wrote:
> I was wondering if multiple TNC's could be connected together using
> something like Bob's ZIP-LAN?
> http://www.aprs.org/txt/zip-lan.txt
> I was thinking of connecting multiple TNC's together with out radios.
> Would that work and if How???
> Tyler N7UWX
You'd just use an audio mixer.   Connect each TNC's TX-audio-out to an 
input of the mixer, and the mixer's audio out going to the RX-audio-in 
of  each TNC wired in parallel.  If you configure the audio-in of each 
TMC to Hi-Z (greater than 5 or 10K) you can easily drive 10-15 TNCs in 
parallel from the 600-ohm LINE-OUT of a typical audio mixer.

If you are using just two TNCs, just connect the TX-audio-out of each 
unit directly to the RX-audio-in of the other one; i.e. an "audio null 
modem" or crossover cable. 



Stephen H. Smith    wa8lmf (at) aol.com
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