[Elecraft] K3 COOLING VENTS

[Guy Olinger, K2AV]

I believe you make my point perfectly. Folks are complaining about displayed 
K3 circuit board and PA heat sink temperatures (not air temp) of 35-45 C as 
if they were somehow dangerous.

While individual components can exceed a measured temp spot in a device, 
good engineering practice in selection of components for their individual 
dissipation in working circuits will insure that the measured spot is 
representative so far as safety is concerned across the circuit.

In the case of a piece of ham gear, anything not so engineered, e.g. a 
poorly designed hot spot, will be destroyed by contesters, and broadly 
complained about, as so well demonstrated over the decades.  Aptos is well 
aware of PVRC and NCCC gossip.  : >)

Blown solid state finals in HF rigs have been a common complaint in said 
decades-long gossip stream.  By height times width times depth volume the 
KPA3 is mostly heat sink and a third of the K3 back panel space is fan mount 
to pull air across said mostly heat sink KPA3. The K3 is a very conservative 
design, heat-wise.

73, Guy

From: "David Woolley (E.L)" <forums at david-woolley.me.uk>
>> an INTERNAL reading.  If 110 F is a fault temperature, then you could
>> destroy your K3 by leaving it out in the sun.
>
> That's not a valid comparison.  The sort of temperature that will cause
> rapid damage is 150C for silicon semiconductors, something like 100C for
> electrolytics, 75C for the 1N34 germanium point contact diodes, if it
> uses them.  These temperatures are reached when the equipment is
> operating at full power and the insides of the devices are much hotter
> than the point at which the temperature sensor is placed.  If you leave
> the equipment out in the sun, powered down, and the case temperature
> reaches 45C, the inside of the semiconductor devices will also be at
> 45C, well below 150C.  It may be lower, because of thermal inertia.
>
> Typical consumer equipment is designed to tolerate an air temperature of
> 45C whilst keeping the core temperature of internal devices well within
> safety limits.  If you actually operate at that sort of temperature, the
> case temperature and internal temperature will be significantly higher.
>
> Leaving electronics exposed to the sun can, of course, result in
> destroying some of the more temperature sensitive components, as case
> temperatures can get a lot higher than 45C.   Having a large thermal
> mass will help protect the equipment as the sun should start to go down
> before the maximum temperature is reached.