The heat dissipation with simultaneous electrical insulation is ensured by a 3mm thick EC360BLUE thermal pad from ExtremeCool. This heat conducting pad has a thermal conductivity of 5W / mK and is attached over the entire surface between the circuit board and the heat sink.
To do this, first peel off the thicker protective film, position the PAD at the bottom of the circuit board and press it lightly on. Then peel off the thinner protective film and position the board with PAD on the heat sink. The kit includes 2 PADs with a thickness of 2mm and 3mm.
Whenever the PA board is mounted on a larger plate or heat sink, there are problems when screwing on the SMA connector when using the 3mm PAD. It is better to stack the two PADs here. With the resulting approx. 5mm thickness, the distance between the SMA socket and the heat sink is sufficient. It is sufficient to compress the PADs only slightly.
The heat sink should be dimensioned a little larger for long continuous transmissions, e.g. for digital data transmission with the AMSAT-DL high-speed modem or when used as a driver for DATV.