AirPort signal weakens with temperature - what cause?
My faithful MacBook1,1 (now running Snow Leopard) has recently started to have problems with the AirPort. This appears at home and in different locations, base stations, and I've checked with two other systems that the WiFi signal at home is stable.
When I turn the mac on (or awaken it from sleep) after it has been off/asleep for some time, I have good WiFi signal (~54% on iStumbler), see neighbouring networks etc. I can see that initial chipset temperatures are ~35C (using Temperature Monitor).
Within a few minutes, as the chipset temp raises above 48C, the signal from my router drops to <25%, the neighbours disappear. In other places, where the initial signal is weaker, it goes below 15% and I lose connection.
I have tried to disconnect and reconnect the antenna connectors and clean the Airport card connector, but with negligible improvement.
If I keep the fan fixed at 6000RPM (with smcFanControl) the chipset stays around 45 deg. and the WiFi signal remains at ~30% (or less but just usable where the signal is weaker at the beginning).
Can someone suggest what I can try to decide if it's an AirPort card problem, an antenna problem or a motherboard problem? Being this an old laptop, I don't want to waste money replacing the AP card if that is not the source of the problem.
PS: the card is the standard AirPort Extreme (0x168C, 0x86), FW Atheros 5424: 18.104.22.168; running Mac OS X 10.6.2 (10C540)
Is this a good question?