VHF APRS Beacon

This is an early design sketch of VHF (2m - 145 MHz) APRS beacons that are small and can be placed in vehicles like ambulances or fire trucks.

Key Points

Si5351 module powered by the usual 25 or 26 MHz 0.5 ppm TCXO.
Si5351 generates 145 MHz Two-Tone APRS RF output directly! Using an Si5351 for APRS (Automatic Packet Reporting System) transmission via FSK (Frequency Shift Keying) allows us to generate highly accurate AX.25 packets directly at the RF frequency (e.g., 144.390 MHz), eliminating the need for a separate modulator and VCO.Since APRS typically uses AFSK (Audio Frequency Shift Keying) fed into an FM transmitter, generating FSK with an Si5351 means directly shifting the carrier frequency or the VFO instead of modulating an audio tone.
INNOTION YG602020 gain block into ATTN and then into INNOTION YG401530VB driver block. Add appropriate filters between stages!
Use Mitsubishi RD15HVF1-501 MOSFET as finals
Easy and more than 1W RF output?

https://how.aprs.works/lora-aprs-bringing-aprs-into-the-21st-century/ (LoRa APRS FTW!)
LoRa APRS @ 868 MHz looks very promising!
LoRa APRS @ 433 MHz seems best for cities and dense urban settings - Let's do a PoC with it!
UHF APRS - not very well explored - skip!

Results: To be built and tested soon!