I aquired a Siskin Tiny-2 clone from eBay, along with a DB9 female to female cable and a USB to Serial adapter. The lights came on when I applied power, but Putty just showed gibberish when I tried to connect. The Tiny-2 manuals are readily found online, and claim that the standard 8N1 settings should work, but I ended up needing:

• 19,200 baud
• 7 data bits
• Even parity
• 1 stop bit

If that still doesn't work, open up the case and check for a Terminal jumper near the front left of the board and check the selected speed!

Once configured and powered on, the version information is displayed:

PacComm TINY-2 Packet Controller
AX.25 Level 2 Version 2.0
Features:
  KISS
  PERSONAL MESSAGE SYSTEM V 3.0
  CLOCK CHIP SUPPORT
  CWID
Release E1.1.6D4  September 18, 1990 - 32K RAM

Perhaps unsurprisingly for a device that's over 30 years old, the 3V lithium backup battery is dead - a CR2032 and holder should fix that.

Some of the Taits have an external interface board which brings out all the audo signals nicely - mine didn't Instead it had a 15 pin connector with an almost bare board. With help from various OARC members we managed to work out the required connections from the DSUB to the 5 pin DIN on the Tiny-2

            Tait        Tiny-2
PTT         Pin 2       Pin 3
TX Audio    Pin 3       Pin 1
RX Audio    Pin 5       Pin 4
Ground      Pin 4       Pin 2

This let me receive packets, and transmit test tones, but normal packet sending didn't happen. I eventually realised the Tiny-2 is expecting squelched audio for DCD (Data Carrier Detect) but the feed from Pin 5 was not squelched. There are various external DCD circuits to be found online, but for now I've just taken the External Speaker audio that's available on the power connector!