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Category: DIY

Coax relay PCB for HF antenna switching

This is a simple board that switches 4 antennas to a single transceiver. It features SO-239 coax connectors, relays with popular footprints and flyback diodes. Unused antennas are grounded. It can be driven by virtually any controller in the shack.

Continue reading “Coax relay PCB for HF antenna switching” →

Practical NodeMCU endurance with a big NiCd battery pack

Some time ago I have built a WiFi thermometer with a NodeMCU and a 6Ah recycled nickel-cadmium battery. WiFi is probably the least power-efficient communication methods, but I was curious how long could a NodeMCU run from a big battery pack.

It took some time to get meaningful data…

Continue reading “Practical NodeMCU endurance with a big NiCd battery pack” →

Antenna switch & rotator controller

This is a two-in-one device. It can be set up to:

  • switch 7 antenna relays from a PC over USB or using transceiver band output
  • control an antenna rotator using buttons and LCD or from USB

Continue reading “Antenna switch & rotator controller” →

Universal antenna rotator controller

mg-rotor1

This is one of my older projects. I designed it for a friend of mine when he became fed up with his Rot1prog controller going bonkers all the time. I wanted it to be something as simple as possible, but still doing its job, easy to use and easy to service.
Continue reading “Universal antenna rotator controller” →

Recent Posts

  • Oscilloscope bandwidth benchmark
  • STM32 stop mode & EXTI wakeup – example without HAL
  • Matching STM32 hardware CRC with standard CRC-32
  • Coax relay PCB for HF antenna switching
  • Fast integer scaling on Cortex-M0
  • Reducing FFT code size of CMSIS DSP
  • Debouncing buttons on EFM32 Happy Gecko
  • Beware of JDY-30 Bluetooth SPP modules

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