Getting KAM-XL APRS TNC up and working

After much frustration trying to get my old KAM-XL TNC up and working I finally got it all back up a few weeks ago. For the sake of future hackers I'd like to share the steps it took to get it all configured.

First off, buy the correct cables for your radio and hook it up. Less problems to troubleshoot for you in case things don't work right. For me both the Yeasu FT-2000 and my Kenwood D710 radio hooked directly to a single port on each radio. For the Kenwood D710 You want to attach to the DATA port on the back of the unit; for the YEasu FT-2000 you connect it to the PACKET port. Obviously each radio type has its own name for the port to use, so that part you will need to figure out for yourself.

KAM-XL in action

The hard part for me was getting the radios configured and properly tuned. Most of the information I could find on the internet gave misleading and often blatantly wrong information as far as this goes. The first, and most glaring issue, is that most internet sources claim the tuning frequency for the KAM line of TNCs (which I took to include the KAM-XL) was 10.14760 MhZ USB or the equivalent LSB frequency. I prefer to use USB since the frequency is so close to the band edge and some radios will erroneously block transmission if using USB; which was the case on my FT-2000. The actual frequency you want on HF for use with the KAM XL is 10.14710 Mhz USB. For the VHF radio you will want to tune to 144.390 Mhz FM in the USA, outside of the USA the frequency may differ.

This should be enough for the radio to work, but there are a few other settings I found improved reception on the HF radio, my Yeasu FT-2000. The ideal settings for me were as follows: Attenuator off, IPO ON (no pre-amp), FLT Thru (the VRF should be turned off), R. FLT 6Khz, AGC off, Noise Blanker off, Transmit Power 25W or less. Since I see no difference when i transmit at a full 100W either way I keep it under 25W. Though for my radio I did not see any decrease in performance at full power.

For the Kenwood D710 the only important settings seem to be the squelch and the TNC setting. Squelch should be set such that you hear incoming beacons but static gets squelched when no incoming signal occurs. If you don't do this the TNC will think the radio is always busy and will never send outgoing packets, only receive them. The TNC setting should be off such that neither the APRS TNC nor the KISS TNC are engaged. If you see any of the following on the display then the TNC is still engaged and must be turned off: Packet12 or APRS12. The number 12 may vary depending on the baud setting of the radio at the time.

Next, we want to set a few things on the TNC itself. The easiest approach is to use KISS mode, in which case none of this matters and you can get up and running right now. ui-view or any APRS software can get you up and running in KISS mode. However if you wish to use the TNC in host mode or as a standalone TNC not hooked up to a computer then you will need to tweak the settings a bit. Also ui-view can still work with the TNC in host mode (as opposed to KISS mode) but since the TNC will send out its own beacons and status packets you will want to disable ui-view from doing this or else you will have duplicate packets.

The settings of the KAM-XL you need to set, at a minimum, in host mode are as follows: MYCALL, HBAUD, and BTEXT. MYCALL should be set to the call you want to use on each port separated by a slash. So if you want no ssid on the HF port (same as ssid of 0) and a ssid of 1 on the VHF port you would do something like "WI2ARD/WI2ARD-1". Similarly if you want to transmit out of both ports you will need to set HBAUD to "300/1200". Finally set BTEXT to be your beacon text including coordinates (if you use a GPS attached to the KAM-XL this can get set automatically). My BTEXT for me was set to "!3955.05N/07510.06W&". Everything after the ampersand is the comment, this can be anything, and the data before the ampersand are the coordinates.

That's all there is to it, your KAM-XL should now be up and running in host mode. One thing to point out though, do not expect to hear many incoming packets, a few a day at most. The KAM-XL works with the older AX.25 over FSK modulation which isnt very good on HF (though works fine still on VHF). For this reason not very many packets will get through. Luckily Robust Packet Radio (RPR) is a new type of modulation that is quickly replacing APRS on HF. While RPR is backwards compatible and will still pick up the older APRS beacons the KAM-XL itself is not capable of RPR. By moving to RPR you will notice a significant increase in the quantity of received packet from the APRS network. I highly recommend updating to a SCS Tracker (the only TNC capable of RPR) if you want the best results from APRS over HF.