Remote Station active

The last couple of years I’m facing much QRM from rf devices and bad solar inverters. To the East the noise increase is sometimes up to 20 dB (!) which makes low signals modes likes FSK/MSK and FT8 nearly impossible.

13 ele LFA antenna 144 MHz @ 5 mtr ASL

This is why I decided to build a station which can be placed and controlled remotely. The station is located appr. 3 km of my home QTH and has wired internet. The noise level dropped by 20 dB towards eastern direction, a big improvement compared to my home QTH.

The rf setup consist of a HermesLite2 SDR radio with a 28-144 MHz transverter and a 400W DIY amplifier with built-in coupler to measure forward and reflected power.
The SDR is controlled by software from SDR-RADIO.COM and running on a small PC which also runs MSHV for the DIGI-modes like FSK/MSK and FT8. The PC is controlled via the internet using a secure RDP connection with VPN (WireGuard).

Inside remote station
  • mini PC
  • 400W PA with coupler
  • SDR with 144-28 MHz transverter
  • RPI with power relays and rotor control
  • internet router with VPN connection
  • PSU for PA and rotor control unit
web interface running on RPI

Through the webinterface I can

  • control the antenna
  • calibrate the position sensor
  • wakeup the PC (if powered down)
  • turn on/off SDR and PA
  • read forward/reflected power
  • read temperature of cabinet and PA (@ MOSFET)
Antenna tower

The antenna tower can be taken down by 1 person in case it needs adjustment and/or repair.

Update march 2024:
I’ve upgraded the SDR transceiver with a 10 MHz TCXO, an ADF4351 PLL to generate a stable LO, an ANGLIAN downconverter (144-28MHz) and also a new SSPA based upon a pair of MRF300 FET’s with appr >400W output.