Weekend project, do APRS with your KT8900 transceiver
This little cheap Chinese transceiver can be found on Ebay, or Aliexpress for 60$, supporting VHF/UHF, can Tx up to 25W. A complete description and testing page is available on G7EOB website
You plan to drive for a long way? broadcast your position on APRS Network, with some components you can build a small tracker. Arduino sketch is based from Trackuino, EA5HAV Javi
Trackuino is more intended to be used on ballon flights, but can work for APRS general purpose.
With some minor modifications, the tracker can send position depending of speed of the vehicle. Reading var gps_speed parser and set the APRS_PERIOD do the job.
Just bellow, is the schematic, D3 is used to generate the modulation, through the trimmer you can adjust the modulation level, D12 is used to saturate the transistor and do the PTT, GPS1 is GPS shield, but for my test i have used a old EM406. A0 is used to monitor the battery voltage with a resistor divider. 10k/3.3k, a temperature sensor LM60, is connected A1. All parameters, like callsign, Gps baudrate, pin assignation …. can be set into the config.h file
- Arduino Nano , or Mini, i prefer Nano because it’s powered @5v, so no need external level shifter for the GPS connection.
- GPS head, like EM406, or a GPS Board (Neo 7M) …
- A temperature sensor LM60 (option)
- Two resistors to monitor the battery voltage (option)
- 7805 voltage regulator with two tantalum capacitor
- A 2n2222 transistor to drive the PTT
- A 10K trimmer with a 1uf cap
- A short network RJ45 cable
- Wire, pin header, veroboard
Yes, i need a little nice box
It’s more clean with a true pcb and a nice box.
Download file (pcb ARES file, Arduino sketch, shematic …)
Tnx for such a great and easy project worked on first tryout 🙂 !
The simplicity to get it running with only 3 suporting components is nice, compared to many of the other projects around.
using it with one of my old uv3r Baufengs with great sucsess, will box it up and put it in the car, planing to drive it with a phone charger to the mini usb port on the Arduino (looses the voltage report but Im good without)
some noted for future builders
compiled and got it working with arduino 1.6.0 but did not work with 1.5.8 and have not tried the new 1.8.0.
It tx once every 50sec
If it does not stop transmitting after after a burst you get rf in the circuit, put a ferrite on the cable, do not use the rubber antenna on the radio close to board.
The gps board and the arduino will blink almost in sync when the gps getting valid gps data.
one of the leds on the arduino lights up during tx.
to program the Arduino remove it from the board or it wont upload the sketch.
A simple way to test it without radio is to connect the audio from the board to your computers mic/line in and run qtmm-1.0.37-win32 to decode the audio.
best reagrds Mikael – SA6BSS
I can only find the pcb whit 18650 but the one on the picture. Is it possible to get the files for that version?
73s de Pedro CT7ARQ
Hi Pedro, you want the firmware or the gerber file ? i have some extra PCB
Gerber file and firmware if possible.
What board version do you have?
Send me an email.