[Packet] Packet and HTX-252

Wed, 06 Nov 2002 15:48:04 -0500

Hi Justin,

Try Buck Rogers' K4ABT site for TNC-to-radio schematics:

http://www.packetradio.com/tnc-to-radio.htm

Scroll down to find the "Radio Shack" section of links.

Each radio is different, but you'll find that most TNC-to-radio interfaces 
need a resistor, and some a capacitor, for the connection to work.

Let me know if you need more info or have trouble finding a schematic for 
the 252.

Ralph KC2RLM

At 02:21 PM 11/6/2002, you wrote:
>Hello everyone.
>
>I recently aquired an HTX-252 at a very, very cheap price. I would like to
>use this radio with my Kantronics KPC-2 for APRS work. However, I have tried
>and tried and tried to get the pinouts correct but nothing seems to work.
>Can anyone shed some light on this issue?
>
>The TNC seems to have the following pin layout:
>
>         1 tx audio
>         3 ptt
>         5 rx audio
>         6 ground
>
>The Radio has the following layout:
>
>         1 mic audio AND ptt
>         4 5 vlt
>         7 ground
>
>While this looks very simple, it is rather complicated. If I touch Pin 3 on
>the TNC to pin 1 on the Radio, it sits there, waiting for the TNC to key the
>radio (which works!).
>
>However, if I touch Pin 1 on the TNC to Pin 1 on the Radio, it keys the
>radio no matter what. It stays an open key.
>
>Now, if I put all three wires together at once, it open keys the radio and
>stays open, but I can type something in the TNC and it will transmit it. I
>can hear the tones going out.
>
>Does this mean I need some type of resistor on the TX audio line to not open
>unless there is audio present, and if so, what value would you suggest?
>
>Any help would be appreciated and any other comments you have about using
>this radio in a packet enviromnent. Thanks in advance.
>
>--
>Justin W. Pauler, W5JWP
>ARRL OES, Louisiana Section
>E-Mail: [email protected]
>WWW: http://www.w5jwp.org
>
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