[Elecraft] K3 COOLING VENTS

[Brendan Minish]

I think there are a few points that still need to be considered here 

How hot are the hot spots? 10 to 20 degrees C above ambient or 50+
degrees above ambient temp. 10 to 20 degrees above ambient temp is
nothing to worry about. 

The dominant heat source is the voltage regulators, adding the Sub RX
increases the load on the voltage regulators so they in turn run a bit
hotter. The primary cooling mechanism for these voltage regulators is by
thermal conduction to the side panel, not by convection. Keep the
side-panel cooler and the regulator area will be cooler too. 
If this is a route you really want to go down then I would propose
installing an external finned heatsink on the outside of the K3 in the
vicinity of the regulators, reuse the screw holes for the regulator to
mount the heatsink, be sure to clean down to metal on the side-panel
under the heatskink and use a thermal grease. This will be a lot more
efficient than chopping extra holes in the case and if you want to sell
your K3 someday all you will need to order is a new side-panel       
 
The Sidepanel is in reasonable thermal contact with the rest of the
chassis, you may also find that the radio runs cooler if you set the
fans on low so they are running all the time at low speed. 
You could also use a slowly turning external fan to blow air up at the
right underside and along the right side of the radio. 

In my opinion the thermal design of the K3 is just fine the way it is,
all components are operating within their thermal specifications by a
very wide margin and internal temperature in the vicinity of the ref
oscillator stabilises quickly after power on.

The K3 runs much cooler than many other radios I have used, it's just
that with many other radios the inner chassis is not in good thermal
contact with outer chassis so you remain unaware of how hot things are
getting around the voltage regulators etc. 

Warm is fine, too hot to touch is probably not..


-- 
73
Brendan EI6IZ