[aprssig] Multiple TNC's connected to one radio

Michael Barnes barnmichael at gmail.com
Thu Oct 26 22:11:04 EDT 2017

For a receive only situation, I think I would scrounge up an old scanner
and have a completely separate receive setup. You can find cheap
programmable scanners for just a few dollars. I keep several around for
just such purposes.

Michael WA7SKG

On Thu, Oct 26, 2017 at 12:41 PM, spam8mybrain <spam8mybrain at yahoo.com>

> Ah, but what if DireWolf is one of the TNC's he wants to test? :-) It
> sounds like he wants to compare different TNC's audio processing.
> Probably a larger issue here is if the TNC's being compared demand
> different audio levels. Adjusting the shared audio signal amplitude for
> best performance on one TNC might ruin the performance of the other TNC
> (signal lost in the noise or overloading and clipping/distorting in the
> TNC's analog input). If you really want to do this right, you might want to
> use an audio distribution amplifier with independently adjustable levels
> for each output feeding a TNC; incidentally, this would also eliminate all
> issues of loading down the input source.
> Just my $.02.
> Andrew, KA2DDO
> -------- Original message --------
> From: "John D. Hays" <john at hays.org>
> Date: 10/26/17 14:43 (GMT-05:00)
> To: Max Harper <kg4pid at yahoo.com>
> Cc: aprssig <aprssig at tapr.org>
> Subject: Re: [aprssig] Multiple TNC's connected to one radio
> It should work, but I can't vouch for specific TNCs.
> Another approach would be to use Direwolf (https://github.com/wb2osz/
> direwolf) which would give you more sampling opportunites.
> On Thu, Oct 26, 2017 at 9:21 AM, Max Harper <kg4pid at yahoo.com> wrote:
>> I would like to connect 2 tnc's to one radio. One would be
>> transmitt/recieve and the other recieve only. This would be to test the
>> decoding of a couple different tnc's. Am I likely to run into any problems
>> connecting the speaker jack audio into 2 tnc's? Would the additional load
>> cause me to have to readjust the audio level when I connect/disconnect the
>> second tnc? My thoughts are since the speaker jack audio is low impedance
>> (8 ohm) and the tnc input is much higher (hopefully) is that it will have
>> little to no effect.
>> Just thought I'd ask before wasting my time making a cable.
>> Max KG4PID
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> --
> ------------------------------
> John D. Hays
> Edmonds, WA
> K7VE
>    <http://k7ve.org/blog>  <http://twitter.com/#!/john_hays>
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