Ray Wells

That's not quite correct. For receive, the difference between the 1200 and 9600 ports on the rear socket is that the former has de-emphasised audio while the latter has "flat" audio from the discriminator. There are reasons why using the discriminator output for 1200 packet is often superior for many hardware TNC/modems that aren't smart enough to compensate for relative tone levels (1200/2200Hz) when they are wrong. Soundcard style modems like Direwolf are far more capable and less particular in this regard. If you want to know why the correct audio is important, take a look at this site with pictures and a very simple explanation.

I know I flog that site and will continue to do so because if everybody using packet read that article and implemented correct audio practices there would be a lot more stations having much greater reliability with packet radio/APRS communications. If I sound like a grumpy old man, I am. I've been involved with packet since about 1985 and the biggest single factor for people's
woes and failures with the mode remains wrong audio setup.

For transmit when using the rear socket, the radio will probably select the right option depending on whether you choose 1200 or 9600 for the speed in the radio setup, like my Kenwood TM-V71A does.

Ray vk2tv

On 24/6/20 3:17 am, Jim Lange wrote:
You need to use the 1200 port on the radio. The other is for high speed packet and won’t work with a TNC that isn’t made for it. Otherwise all is good. 

Sent by me

On Jun 23, 2020, at 13:13, Al Massaro <almassaro1@...> wrote:

OK I am thinking of trying a TNCPi with a ft 7900r, the pigate site shows the pinout for a FT 2800/2900 using the mic port. My question is my 7900 has a rear data port why can't I use it? Her is a comparison of the 28/2900 mic pinout and my plan for my 7900. Do I need to figure out and use the pinout for the 7900 (MH48A6J) MIC PORT instead? Below left mic pinout from website, Below right my plan for 7900.

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