The main thing to remember about heat sinks is unless there¡¯s a heat transfer path out of the assembly (i.e. convection, conduction, or radiation), ?a heat sink only slows down the temperature rise of the devices being heat-sunk. This is fine for low-duty cycle transmissions but it won¡¯t help much for long transmissions like WSPR. Adding a small raspberry pi fan on top of the heat sink would help but not much in a closed case environment. The best you can do in a closed case is conduct the heat to the board using a metal bolt of some sort and hope the entire board acts as a heat sink. As Bruce mentioned, a VERY thin layer of heat sink compound between the FETs and heat sink will improve the rate of heat transfer.
On Fri, Jan 12, 2024 at 4:43?PM Bruce Akhurst <
bruce@...> wrote:
Did you do any thermal modelling on this ??
(Thermal tape is a pretty poor heat conductor when uncompressed .. )
Use a fixing screw instead to apply pressure to the sink -FET interface and apply the thinnest possible layer of thermal grease to the packs point of contact?
