Kenwood TM-V71A

[Daniel Wee]

https://planetkris.com/2009/05/setting- ... -for-aprs/

Data interfacing
https://groups.io/g/direwolf/topic/dire ... 4952540?p=

[Daniel Wee]

Main unit to display unit protocol

https://kk4hej.wordpress.com/decoding-t ... -protocol/

[Daniel Wee]

Second digipeater hardware

1. Vention USB soundcard (Challenger SGD10)
2. Raspberry Pi 4 8GB
3. PR1 and PKD pass through 1:1 Bourne audio transformer with 10uF on radio side
4. GPIO 18 as PTT
5. GPIO 23 as DCD

[Daniel Wee]

Packet levels

On our implementation, with the notch on the top and looking into the connector from the 1-o'clock position clockwise:-

1. PR1 from the radio into the TNC
2. PKS - PTT keying
3. output from the TNC to the radio PKD (calibrated for an output of 40mV p-p)
4. Ground to radio DE

The output from the soundcard is quite strong and requires a 10k-pot to bring the level down. That said, the alsamixer values we settled on in the TNC are as follows:-

Speaker 28
Mic (muted) MM
Capture 48
AGC (muted) MM