Old TNCs - 2024

Progress

Has been such that what once could be achieved with an 8-bit Z80 or 6502 now requires a 32-bit or 64-bit processor and a sound card. Mechanical teleprinter affictinados probably said that about the 8-bit micros.

In Use (January 2021)

Away from the APRS frequency there is a recent revival locally in this part of the UK on 144.950MHz.

SWL

On the Amateur Radio bands below 30MHz, there is very little 300bps packet activity. RTTY is still quite active 45.45bauds, 170Hz shift. If you want to run AFSK locally then it's 1225/1445kHz please.

Most of the multi-mode controllers make great RTTY and NAVTEX decoders.

• • RTTY, 50 bauds, 425Hz shift :: Hamburg Meteo on 4583kHz, 7646kHz and 10100.8kHz

  • NAVTEX (set AMTOR or NAVTEX mode as it is AMTOR mode-B FEC) :: 518kHz and 490kHz

Inventory 

I have a collection of old packet multi-mode TNCs, most of them are working but some (particularly the Data Engines) are in need of repair.

• • AEA PK-232MBX (later version, red/yellow/green LEDs). Firmware v7.2.

  • AEA PK-900 (it's huge!). Firmware v7.1 with pactor

  • AEA PK-88 Firmware 23-AUG-91.

  • AEA DSP-232. Original firmware that causes reboots on packet but a good performer on RTTY and NAVTEX.

Why did AEA change the design and use different radio connections on almost every TNC they made? None of them actually match. PK-232 used some Molex connectors (BAD), the PK-88 used a latching 8-pin (microphone) plug (GOOD). Then the PK-900 and the DSP-232 moved over to 5-pin/180 DIN sockets (STANDARD).

• • Kantronics KAM. Firmware v6.1 - last version before enhancement board with Pactor 1.

  • Kantronics KAM V3.0. To be upgraded to 6.1

  • Kantronics KAM with Enhancement Board. Firmware v8.2E

  • Kantronics KAM PLUS. Firmware v8.2P.

  • Four Three Kantronics Data Engines with 1200 and 9600 modems

  • Kantronics KTU WeatherNode. Looks like this could easiliy be interfaced to an Arduino or NodeMCU. (TODO).

       Looking for Kantronics Manuals and Schematics? Go to http://kamstuff.yolasite.com/

• • TNC2DL MkIV. A TNC2 clone. I built this myself, ran on my packet node for many years but now used for tinkering with APRS. Firmware TAPR TNC2 v119.

  • A pile of BSX2 TNC PBCs, some with 7910 modem chips, others with G3RUH 9600 modem PCBs.

  • PacComm TINY2 and another Siskin-branded TINY2

  • PacComm TINY2-Mk2

  • PacComm SPRINT-2 / SPIRIT-2 9600 - 57600 Bps high speed TNCs plus all manuals/schematics. None to be found online so maybe I'll finish my PDF scans at some point.

  • Still some CT2 units knocking around. Made a great 2-port TNC in years go by thanks to some clever programming by G3ZFR, but presently they just prevent my shed from blowing away in this windy weather!

  • MFJ-1278 plus MFJ-56A (release 4.1 $66 32k mailbox plus PACTOR) plus MFJ-43 (real-time clock) plus MFJ-780 (DSP FIlter)

  • MFJ-1278B/DSP plus MFK-44 (RTTY Tuning Scope Adaptor). 

  • MFJ-784B DSP filter, can be used as an external DSP filter with a 1278 or 1278B.#

  • MFJ-1289 Multicom software for these controllers.

The 1278 design appears to have been an expansion of the TAPR TNC-II packet TNC design that uses an XR-2211 FSK demodulator and XR-2206 tone generator. It has a nice tuning display reminiscent of Kit the car in Knight Rider... The aesthetics of these controllers aren't particularly pretty, but they can be made to work.

I ought to start a dedicated page for the 1278 series. The original 1278 works great for RTTY and NAVTEX, however the 1278B with DSP appears to be more fiddly and doesn't quite work with 425Hz shift RTTY. Some investigation work here as there are a lot of jumpers to configure.

A lot of the older manuals have now vanished from the MFJ website but i've managed to find all the relevant ones thanks to Google. There are plenty of catalogue scans around on the internet too...

• • DRSI PC/PA card dual 1200 bps tnc

  • DRSI PC/PA card 1200/9600 bps tnc

  • A Kenwood TMD700E which has a built-in 1200 andd 9600 TNC. Currently the TX/RX for most of the above via a 6-pin mini-DIN connector.

Help and assistance?

I have limited availability but may drop into some of the packet radio forums from time to time. I'd expect anyone who wants to set up a packet station to get familiar with RS232 serial interfacing as that's where I see most of the queries. No USB plug-n -play here! You should at least be prepared to do some soldering of cables and troubleshoot signal levels with an oscilloscope or a multi-meter. Check the negative voltage supplies inside Kantronics TNCs as these are notorious for failing because the electrolytic capacitors have dried out. If you're more adventurous and familiar with 1970s/1980s tech then you might want to get yourself an EPROM programmer so you can replace your firmware.

Sales?

On a case-by-case STRICTLY NO RETURN basis. UK should be fairly straightforward. US/Canada periodically as I travel to the US every 12 weeks. EU, rest of the world - means I have to deal with customs declarations and so will you on import.