January 22, 2005
Update on the W5EX APRS-KISS TNC-UIVIEW Mobile
This is a follow-up to the 2003 entry to our web page concerning APRS implementation.
Tiny-Trakä
First, for those not needing an in-auto read-out of station position data, just purchase the Tiny-Trak. (www.byonics.com/tinytrak).
This unit performs flawlessly for me. It will fit inside many currently available land-mobile VHF radios, thus freeing up your expensive rice box for more pressing duties. Do be careful with deviation settings (see notes elsewhere in this article).
Checking out club digis.
Intertie has digi-peaters stretched out from the Gulf coast to west Texas. They suffer all the usual weather-related indignities, as well as failures sometimes provoked by us. Thus, a mobile test bed is necessary.
But I drive up to a digi, see my radio transmitting a packet that I can hear on a talkie – yet there seems to be no response from the digi
OK, here’s where I got caught, too. Even if you have wired a Tiny-Trak with a forced transmit switch, you may not get a response. Probably, the digi is programmed to repeat any given station only once every nn minutes. So you get just one try at a time. With UI-View, there is a better way.
1. Click on “Stations”
2. Find the button for “Query” Click on it.
3. Type your exact mobile call sign – such as W5EX-9 in the “Station” box.
4. Type the exact call of the digi – such as WX5II-11 in the Digi Path box
5. Click “OK”
6. If the digi is working, and has not seen you just before, UI-View will switch automatically to the Message screen and ring a bell.
7. Is this cool, or what?
As noted elsewhere, we wanted a way to have a computer lap top display, without the expense of the $600+ rice boxes. We found the KISS TNC published by John Hansen, W2FS, in QST, November, 2000 – as described above, bought and built the kit. We needed John’s help to get it going without intermittent failure. The problem was corroded IC socket pins. If you do buy the kit (Far Circuits) I suggest purchasing machined-pin sockets (Hosfelt).
But I want my position to plot, as well as others.
Fortunately, the UI-View software carries the answer, found by clicking on HELP and then looking for HSP switch. You will find an explanation and a schematic of the very clever sampler that places your personal GPS output on the map, along with stations heard on the radio.
I built this simple circuit into a small plastic project box from Radio Shack. Short cables carry DB-9 connectors to interface with the GPS, my computer and the TNC output from the radio receiver/transmitter.
I am using a VHF Motorola Micorä, converted to 144 MHz. My antenna is a Motorola TAD 6112A, a 1/4l whip, which comes factory cut for 144-148 MHz.
Connect your GPs to the HSP switch; connect the TNC output to the other input of the HSP, and the output of the switch to the computer serial port. P. Franc (www.p.frank.com) makes serial cables for Garmin. You can also use the Radio Shack Digi Travelerä. See notes elsewhere concerning this excellent GPS receiver.
You’re using a Micor? They work on 2 meters?
Yes, indeed, they do. Consult W3KKC’s excellent Web page http://www.repeater-builder.com/rbtip/sensitronRX.html and associated pages covering transmitter alignment, etc. In particular, pay attention to Kevin’s instructions for removing microphone bias: http://www.repeater-builder.com/rbtip/micortxbias.html. You do not need to do his duplex conversion. Ignore that.
After completing the conversion, you will find that you are short of TX audio. On the exciter, solder in a .068uF ceramic cap across C 408. To avoid audio delay, JU 405 must be replaced, if not present. Short out R 431. Move the R402 side of C408 to the other side of R402. Feed Tx audio to pin 12 of P902.
Pick off audio at the emitter follower of the audio/squelch board, pin 3. This is a fixed level, independent of the speaker volume.
The manual for VHF Micor is Motorola part number 68P81008E40.
Setting up the station.
Follow John’s instructions for the KISS TNC (not the ‘APRS Mode’ stuff) Use 4800 Baud setting
For the Garmin GPS: Select ‘Interface’ from menu, then choose None/NMEA and 4800 Baud.
In UI-View: Click on ‘Comms Setup”. Select 4800 Baud, 7 bits, no parity, 1 stop bit, and KISS Host Mode. Ignore ‘KISS SETUP’. Click OK and data will load into your program.
In UI-View: Click on Station Setup. Select your call sign, latitude and longitude for your fixed station. Use RELAY, WIDE, WIDE for the UNPROTO address, unless you know all about this mystery and have your own preferences. Your fixed and Internet beacon intervals should not be less than 60 minutes. Mobile 5-15 minutes, depending on your location – use longer intervals when cruising at higher speed. Select a symbol to be posted on receiving station maps. Click OK and data will load into your program.
Setting up the radio transceiver.
These comments apply to all APRS radios. Do NOT over-modulate. About 3.2 kHz is plenty. On the receive side, again, keep it down. Unlike with GE radios, I found no need to insert any compensation in the Micor receive audio line. If you lack access to a service monitor, I suggest working with another ham who has a working APRS station.
Conclusion
With an inexpensive laptop from E-Bay, (Panasonic CF-25), some DB-9 cables, UI-VIEW, an old Garmin GPS-45, a serial cable, a sampler switch, a KISS TNC kit , and a VHF Micor, I am able to achieve my mission of sending and receiving APRS data, as well as on-site check-out of digi-peaters. The overall cost was far less than for a rice box.
By Larry Higgins, W5EX
Revised:
01/24/05 01:00 PM by
N5VRP, Dennis Rogers, Webmaster
Copyright 2004 by Intertie, Inc. All Rights Reserved
No use of these symbols or phrases is allowed without the express written
permission of Intertie, Inc.
