Tech Note: High Power Radios and Heat

High power radios like the Satel EASy Pro and EASY Pro+ generate a lot of heat while transmitting, so they can get hot to the touch – especially when it is also hot outside. While output power on these radios is up to 35W, they need as much as 120W of power to generate this signal, with the difference ending up as heat (up to 85W of heat).

If radios are getting too hot, there are numerous ways to reduce or mitigate the amount of heat generated. Many of these techniques will also save power and increase run time on battery systems.

  • Avoid using slow GMSK radio protocols including TrimTalk450 and PacCrest-GMSK if possible. These modes can generate up to twice as much heat as more efficient 4FSK modes, like Satel 3AS or PacCrest-4FSK.
  • Reduce transmit power. Often 25W or even 10W of transmit power is plenty to get the range you require. Additional height on the transmitting antenna system, such as using a tripod or antenna mast system is often more useful than high transmitter power to increase range.
  • Use Satel 3AS mode with no error correction (also known as forward error correction or FEC). Error correction adds significant overhead (approximately 30%) which runs the transmitter longer and is only useful in conditions with extremely poor signals. While disabling error correction can reduce range, this is usually not meaningful for 35W transmitters.
  • Make sure the TD light is not solid green. This indicates the radio is in test mode and this will cause excess heat generated and may disrupt the normal operation of the radio system. A blinking green TD light is expected in normal operation and indicates periodic data transmission.
  • Ensure the radio is mounted vertically (antenna connector facing up), so that air can flow up through the heat sink.
  • Get a 25kHz license. 25 kHz channels are up to twice as fast as 12.5kHz channels, so operating at 25kHz will run the transmitter for shorter periods of time and generate less heat. Note: Operating at 25kHz in the United States requires a license specifically authorizing this use and requires the use of 4FSK or faster compatibility modes.
  • If using an EASy Pro radio, consider upgrading to a EASy Pro+. The EASy Pro+ has a wider range over power outputs (1-35W vs EASy Pro’s 10-35W), and is 20-50% more power efficient, which leads to less heat generated.

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