[44net] set txd on Pi-tnc running jnos?

I've just completed the pi-tnc and fired it up with my pi using jnos. It worked first time, but txd is way too short as I'm going through a mountain top digital repeater. Everything is configured for a kissmode tnc for use with jnos.

I'm miffed about how to get out of the software preset so I can use R6 to set txd.

After reading the instruction book for the tnc-pi, I'm still confused as to what to use.

Thanks, jerome - ve7ass