Lawrence,
While the board and washer both absorb heat, there¡¯s no place for it to go other than spread around inside the enclosure. The longer the transmitter is on, the more the heat builds up, elevating the temperature inside the enclosure.
A solution I used for many years in portable radios was to solder metal tabs to the heat-sunk area of the board (at ground potential of course) and either bolt or solder those tabs to the radio¡¯s metal enclosure. This direct-conduction method piped heat rapidly to the enclosure which then radiated away from its large surface area. This was the most effective heat removal strategy in my hi-rel career where fans were not allowed due to their high failure rates rates.
Tony AC9QY
On Sat, Apr 19, 2025 at 5:44?PM Lawrence KC6WOG via <lsgoodwin=
[email protected]> wrote:
I can't speak for the QMX as I haven't built one yet, but with previous designs the washer is not intended to be a heatsink. It's purpose is to hold the finals down flush with the copper pad on the PCB, which is the actual heatsink. The transistors also transfer heat via their leads. I doubt that replacing the washer would accomplish anything significant.
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If I'm wrong, anyone here is more than welcome to correct me. I'm not yet too old to learn, but I am getting there!?
