TNC-Pi User Guide
-13-
6/25/2017
Pin 3: TX Audio
Pin 4: Push to Talk (PTT)
Adjust transmit audio output
Potentiometer
R7
adjusts the level of the transmit audio output. Most people will
find that they need to set it fairly near the minimum setting.
One way to set this is to use two radios, one to monitor the transmitted signal and
the other connected to the TNC-Pi.
1.
Key the radio connected to the TNC-Pi manually by pushing the PTT button on
it.
2.
On the other radio you will hear a continuous tone (even though no data is
being transmitted… you don’t need to be running any software on the
Raspberry Pi to do this).
3.
Turn R7 all the way down and the tone will go away.
4.
Then slowly
turn it up until the volume doesn’t increase any further in the
monitor receiver.
5.
When you reach this point, back it off just a little and you should have it about
right.
Set the transmit delay
The transmit delay (
TXDelay
) can be set either in software or using
R6
. The default
is to set it in software. To change the
TXDelay
parameter, you'll need to use the
pitnc_setparams
program as explained below in the section, Using Xastir.
If you set the value of
TXDelay
to 0 using the
pitnc_setparams
program, you can
then use
R6
to set the
TXDelay
.
Most users will find the default setting for TXDelay to be just fine.
Configuring the Raspberry Pi
The following instructions were based on a downloaded image of the “Jessie”
version of the operating system. I did this by downloading Raspbian, not NOOBs.
It might be a good idea to make sure your Pi operating system is up to date. You
can do this from the command line by entering the following (this assumes you
have either hard wired or wireless network connectivity):
