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1200baud Mini-TNC (Rev0711) for APRS

Last Mini-TNC Project page is here

FoxDigi: 1200 Baud Mini Digi

VixenTrak: GPS-less Position Encoder for FoxView2

Hamcom Interface : Project & Kits

APRS Trackers & Viewers




 Mini-TNC: A 1200 Baud Radio Modem using PIC16F88

Mini-TNC: AN APRS/Packet  TNC.

Last Project page is here.......


 Mini-TNC Rev0711 with Firmware V1.09
 Latest Firmware Upgrade by Dennis/N5VRP

 Firmware Document


 Firmware V1.09

 Evaluation & Test Report of Mini-TNC:
 Doug / W5DUG

 Bernard / KI6TSF

 Uwe / SM6JWU


A Simple PIC88 based APRS TNC: Rev0711

In this project, special attention is paid to get an economical APRS TNC with minimum current consumption and simple task:

1. A stand alone TNC to replace MX614 Modem chip

2. Send & Received APRS data to COM port.

3. Supports "Converse Mode" and Packet/APRS with Version 1.09 firmware by Dennis/N5VRP

Mini-TNC is a PIC88 based TNC which decode aprs packets & route to COM port. Mini-TNC has two D9 connectors for outside communications. J1, a D9F is provided for your transceiver. J1, another D9F is for connection to your PC using a simple serial cable to output your received data to your PC for further processing.

Mini-TNC may be powered by either +5V from USB (J3) or from D9 Radio connector with +8 to 12V DC. In this case, An internal regulator (78L05) provides +5V for digital circuits. Current consumption is well below 20ma (Depending on LEDs) which is good enough for most remote solar powered locations. 

Mini-TNC uses a standard RS232 driver to interface with your PC. You will require a serial cable to configure internal parameters of the PIC88

Project is designed on 10cm X 6cm Double Sided PTH board and results were very encouraging. A free metal case is avail;ble with kits or assembled.

PIC firmware for Mini-TNC is available at 4800 & 9600baud and its at V1.09 provided by Dennis/N5VRP.  Please refer N5VRP Document for more details on new firmware compatibility with your PC.

It should be noted that since no input audio preset is onboard, audio level supplied to this tnc may require careful adjustment of received audio from radio. 

However, a modification to previous design is made keeping in mind varied audio levels. In this design (Rev0711) you may feed receiver audio direct to PIN17 of PIC88 or route thru MPC6023 active filter.


Completed Mini-TNC

Click the image to enlarge

Mini-TNC back connectors:

            USB +5V               TO PC                           TO Radio + DC IN


Mini-TNC Rev0711 Document

1200 baud modem using MX614

V1.09 Formware Details by Dennis/N5VRP

1200 baud modem using MX614

Mini-TNC Rev0711 KIT Parts List

1200 baud modem using MX614

Rev0711 Schematic & Parts List

1200 baud modem using MX614

Configuration Document

1200 baud modem using MX614

Using Hyper Terminal of Windows

1200 baud modem using MX614

Mini-TNC Rev0711 Schematic



1200 baud modem using MX614

N5VRP Firmware V1.09



With this modem, you can use many software available either as a freeware or shareware. Please go thru following links & find one suitable to your communication requirements.
Digital Communication Software Collection
Digital Communication Software links
Understanding Digital Communication



 Buy Mini-TNC Kits


For online payments, shipping charges will be added on secure web page, which are from $5.00 upwards for Registered Air Mail, and based on value/weight of the KIT/Assembled.

"Buy from 2CO", you may pay using your CC or funds from Paypal.

For Money Order, please refer to table provided on MO web page.

Track your order guide

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Terms of sales


 Buy from 2CO   

Mini TNC Rev0711 Complete Kit with Firmware: 1.09
Free cases no longer available
Firmware available for  4800 and 9600 baud

KIT $34.00


2CheckOut.com Inc. (Ohio, USA) is an authorized retailer for goods and services provided by Fox Delta.
Kit Parts List

OR  click hre for Paypal payments:


PCBs may be AVAILABLE FROM our school project website




2CheckOut.com Inc. (Ohio, USA) is an authorized retailer for goods and services provided by Fox Delta.


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