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APRS tracker with DRA818V

I am in the process of finishing the design a APRS tracker with a DRA818V since my previous Arduino APRS Tracker has a dependency of an external radio…

Features list (still open)

  • Cheap with a target price of 50 euro
  • Powered from Lithium-ion battery 18650 or from a Lithium polymer battery.
  • Built-in charger
  • USB/RS232 or Bluetooth communication
  • Temperature sensor
  • Small size (depending on the battery selected)
  • 3D printed case
  • Trying to avoid SMD if possible

I will drop/add depending on the difficulty of the PCB, size/dimensions and the final price

 

Low pass filter

According to references online a need a low pass filter on the RF output of DRA818V due to a lot of harmonics

A Chebyshev 0.1db from W6KWF
Another one from SV1AFN or
LFCN-160+ (https://ww2.minicircuits.com/pdfs/LFCN-160+.pdf)

Both of the above filters work really well in LTSPICE IV

dra818v filter
-3db at 202 MHz
-40db at 300 MHz

dra818v filter
-3db at 166 MHz
-40db at 325 MHz

Another one from rf-tools

LFCN-160+ has-3db at 230 MHz and typical -20 db between 330-480 MHz, but it is difficult to obtain 

Comments

4 responses to “APRS tracker with DRA818V”

  1. SQ3MP Avatar
    SQ3MP

    Billy do You have ready the pcb board ?
    I prepared PCB for SA818, all assembled but my local digi has troubles with decoding
    I think audio structure arduino board -> radio need special construction, I copied Your structure from previous scheme

    Regards

    Reply
    1. billy Avatar
      billy

      No yet, i have recently bought a 3D printer and try to combine both, PCB + case

      Reply
  2. Jason Rausch K4APR Avatar
    Jason Rausch K4APR

    I spent several months a couple of years ago trying to get the SA818 working as an APRS/Packet module. I ran into a lot of problems with the audio ramp up delay and other related issues. Recently, I gave it another shot because I was told the NiceRF version has fixed these problems. To my dismay, the issues are still there. I have a complete APRS tracker designed and integrated the SA818 into a special all in one version, hoping I could get it to work this time. Looks like I will go back to the original design utilizing an externally interfaced radio.

    Reply
  3. billy Avatar
    billy

    This is ineed a good hint for the NiceRF !!! Thank you

    Reply

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