TNC-2 10mhz upgrade kits

Discussion in 'Radio Circuits, Repair & Performance' started by KJ6HZH, Apr 15, 2018.

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  1. KJ6HZH

    KJ6HZH Ham Member QRZ Page

    I'm trying to track down information on the 10mhz upgrade kits that Paccomm and others sold for upgrading the CPU of a TNC-2 based TNC. What was in the kit? Does anyone have a scan of the instructions for this? I can find an appropriate CPU and SIO easily enough, but I don't know about any other parts required or how those are applied.
  2. KB0MNM

    KB0MNM Ham Member QRZ Page

    While I do not have the specific information that you seek, here are a few ideas: 1. Many of the early terminal node controllers were based upon a Zilog Z-80 chip, as were the early Tandy/Radio Shack TRS-80 line of microcomputers- models TRS-80, TRS-80 model 3, 4 and 4P. There may still be some activity in their user groups which could point you to the right folks. 2. Upgrades to the microcomputers mentioned typically involved the replacement of the CPU with an Hitachi HD64180 CPU, which was rated for the 10 Mhz. speed. The speed upgrade often also includes the support chips, therefore common TTL series 74xx chips might then be replaced with 74Fxx ( for fast ) or just newer versions as in 74LSxx ( low-power-schottky ) or even altogether different chip lines ( CMOS 4xxx series ). 3. Just upgrading the CPU is generally not a wise idea, because the timing of the rest of the included circuitry must then be either slowed ( relative to the new CPU ) or possibly be improved. The storage of HDLC protocol and other important TNC-2 specific instructions is often in either an EPROM or an EEPROM, which may or may not be fast enough to run with a faster CPU. Unless you have more time than money, you may want to re-think the reason for your request.
  3. KJ6HZH

    KJ6HZH Ham Member QRZ Page

    Specifically, I'm talking about the kit offered by PacComm for the Tiny-2 TNC. All of the 74xx support logic in the Tiny-2 Mk2 are type HC CMOS.
  4. G0GSR

    G0GSR Ham Member QRZ Page

    I'm sorry, I can't help with the information but I ran my TNC's at 4.9MHz with Z80A and SIO-0 for years without any problems related to not being "fast" enough.
    Even at 9600 baud.
    Is there really a speed problem that would warrant this extra work?

  5. KJ6HZH

    KJ6HZH Ham Member QRZ Page

    I heard that this upgrade is necessary to run a G3RUH type 9600 bps modem.
  6. G0GSR

    G0GSR Ham Member QRZ Page

    I have never heard of that "requirement" and had several TNC's, including a Tiny2 and Micropower 2 running with 'RUH modems.
  7. W9GB

    W9GB Ham Member QRZ Page

    QRZ Query : Paccomm EWM, Tiny-2 models, 2008/2010
    December 2017
    David -
    Yes there was a Kit for the early Paccomm TNC-2 models (like version 1.1 that used inexpensive 4 or 6 MHz Z-80 CPU/SIO parts). I will search my archives, there were instructions sent with those kits, but I doubt that I have those instructions.

    You have to remember that Gywn had various PCB “design revisions” between 1988 and 1994 — LOOK careful at TNC-2 Silk Screen for version number, such as: Version 1.6
    The later PCB versions had full etchings and silk-screens to support the easy addition of various Paccomm “Options” or models, such as add-on modems, DCD support, dual ROM images, PSK-1T model, etc.
    As I remember, the kit contained a 10 MHz Z-80, crystal, and handful of faster 74xx parts. Later TNC-2 revisions used faster Z-80 and TTL parts, for easier 9600 baud upgrade.

    The Paccomm TNC-2 design was “clone” of the TAPR TNC-2 kit design (released summer 1985). Check the TAPR archives, specifically for changes to support 9600 baud upgrade.
    Surplus Xerox 820 units were used with early TAPR TNC-1 designs.

    Gwyn Reedy, W1BEL (sk, Dec. 2006), founded PacComm in 1985. He passed away in an automotive accident in December 2006. His wife ran the company for 3 or 4 more years, and refused offers to sell the business. The business phone number was disconnected years ago and web site disappeared around 2012. There are a handful of amateurs / engineers in Tampa, FL area that worked for Paccomm and did weekly contract/build work for Paccomm, after Gywn passed.

    Paccomm Wireless Radio Systems, Inc.
    751 Knowles Road
    Brandon, FL 33511 USA
    Last edited: Apr 16, 2018

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