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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
