Hi Iain,
It seems that I have overlooked something important when I first read and replied to your post.
[Yes, I know that the TNC-220 runs 2025-2225Hz as the mark/space tones and I have set up dirwolf to work "around" that set of frequencies rather than the 1600-1800 that direwolf starts with..... the dirwolf receives OK].
I foolishly assumed that you were looking at 1200 baud AFSK packet (as is common on VHF or higher frequencies). However your comment about 2025-2225Hz sounds like you are trying 300 baud packet on HF bands. Both Direwolf and your hardware TNC can do both. For Direwolf you control both the baudrate and the actual tone frequencies with the Modem command in the direwolf.conf file.
For your hardware TNC it is a bit more complex. The TNC has two radio ports where the factory default is that port 1 is used for 300 baud packet on HF and port 2 is used for 1200 baud packet on VHF. This default configuration can be altered with jumpers and it is possible to have both ports configured for 300 baud packet or both ports configured for 1200 baud packet. Since you say that Direwolf received a connection attempt from the hardware TNC, it appears that you are using the correct port and baud rate but those things can be deceiving! Direwolf can be incredibly sensitive (depending on the audio hardware) and I have seen it successfully pick up audio signals from a nearby packet station where the only connection between the two was a common ground.
Since your hardware TNC won't be decoding any packets if the baud rate or tone frequencies are wrong, this is something you should definitely double check.
Also be sure the issue "port 1" or "port 2" commands on your hardware TNC to ensure that you are monitoring on the correct radio port.
I can telnet to port 8001 of direwolf and get a "cmd:" prompt
Yes, you can but telnet to port 8001 but by default port 8001 is using the KISS protocol and you are not going to be able to generate a valid KISS frame by typing on your keyboard. You do need either a KISS or AGWPE protocol client applications to use Direwolf to transmit packet data other then beacons. For your test purposes, I would suggest configuring a beacon in direwolf.conf. If you are testing over the air, check the rules that apply to your country regarding how frequent you may be able to send those beacons.
If you are doing bench testing with Direwolf directly connected to the hardware TNC, you can make those beacons very frequent (like every 30 seconds in this example):
CBEACON dest=BEACON info="MM7xxxx testing packet station" every=0:30
73,
Thomas
KK6FPP
