Choosing a TNC

What is a TNC?

TNC is the initials (a fancy word is acronym) for Terminal Node Controller.!
I don't know exactly how they work, just that most TNC's today can decode a number of digital modes, usually - Packet Radio, Amateur Television, CW, AMTOR, PacTOR, RTTY, SITOR, NAVTEX, Fax, GTOR / Golay and ASCII.
With this new mode called PacTOR II though, there are some new TNC's out that support it, and ONLY the new TNC's have support for it.!
How much do they cost? If you buy a TNC second hand, they cost as little as $50 AUD.
Packet is the most common mode used and there are a lot of Packet only TNC's cheap, the more modes you want, the more expensive the TNC of course !
As a general guide, here are some prices - of course these prices may vary.
Second hand:
$50 - 100 AUD - Packet only
$100 - 200 AUD - Packet and PacTOR
$200 - $350 AUD - Multi-Mode
Brand new:
$200 AUD - Packet only
$300 AUD - Packet and PacTOR
$650 - 700 - Multi-mode. (ie, all modes listed above)
What do I need to use a TNC? A TNC won't work without a radio to receive audio from and a computer to display the output.
I am assuming that if you're reading this page you've got the radio and computer , and you wanna know what you might need to get going in digital communications !
Of course, the radio's gotta be attatched to an antenna, for tranmsitting, the antenna's gotta be tuned to the correct frequency, for receiving any length of wire greater than about 15' is good for Short Wave.
How do I set-it-up?

First, do you want to transmitt or just receive?
To receive only here's the go......
A shielded audio cable with a 3.5 mm stereo plugs at one end and a 5 PIN Din connector at the other.
An RS-232C Serial cable about a metre is average from shops.
Your TNC.
To transmitt and receive here's the go......
A 3.5 mm plug to go into the speaker jack on your radio, one microphone plug (with however many pins your microphone socket has on it ) and a 5 PIN Din plug.
You'll need two cables for this, one to go from the DIN at the TNC to the speaker jack on your radio and one from the same DIN at the TNC but this time to the microphone plug.
An RS-232C Serial cable
Your TNC.
Hook it up !!
OK, you've got all the stuff you need, so, lets hook 'er up !
For receive only, all you gotta do is connect one end of your shielded audio cable to the speaker socket on your radio, and the other end to the 5 PIN Din plug. You will have to check the TNC's configuration to see which wires go on which two pins for receive only operation.
Connect the RS-232C serial cable to your TNC and computer.
Once that is done, fire up your radio, computer and TNC. Set-up the TNC and tell it which port you have it plugged into on the computer, then, find a good signal and have fun ! =)
For transceive, all you gotta do is connect one end of your shielded audio cable to the speaker socket on your radio and the other to the correct two receive wires in the 5 PIN Din plug. The other shielded wire we've got with the MIC plug on it, plug it in to the mic jack on your radio, and connect the approriate wires from the other end of that cable to the appropraite pins on the DIN plug, this is so your TNC can "key" your radio to transmit.
Righto, now, configure your TNC, tell it which port on your computer it's plugged into....and either tune to a good signal and have fun listening and later, having a QSO or two or find a clear frequency, make sure it's not in use, then, transmit away !! =)

Why do I need a TNC? A TNC is the interface between your radio and your computer that provides a common language between both, so they can talk to each other ! I mean, two people who only speak one language each, and those two languages are different, can't understand each other, right, well, it's the same idea for your computer and radio, they need a translator and the TNC is it !
Withouth the TNC, your radio and computer might as well be speaking Arabic and Spanish, so they won't understand a thing !
What TNC's, what modes? Well, this also depends on what brand you wanna buy!!
There are a few brands that come to mind off the top of my head.
KAM, AEA, MFJ and PacComm. I am sure there are others...these are the only one's I have seen available in Australia !

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