Hi all, Johnny, VR2XMC wrote:
It should not?be any rocket science, all you need is a piece of thick metal plate to suck the heat from the PA transistors and with fins to facilitate air circulation.
You are right: a thick piece of metal will sink the heat from the PA transistors. But how thick? Too thin and there is little benefit. Too thick and the stored heat in the metal mass actually inhibits recovery time after a heating event.
How many fins? How tall? How far apart? And what combination of all of these gives the most benefit at a targeted small size?
You are right: it is not rocket science, but a dismissive attitude towards the importance of learning the interaction between the variables leads to some of the poorly-performing (not to mention ugly) designs I have seen hung off of several KX3s. I also happen to agree with Elecraft's design criteria which is the same as just about all amateur-radio gear made: 100% power on CW and SSB, 50% power on digital modes. To upgrade this to commercial broadcast equipment performance of 100% duty cycle in all modes would greatly increase the price and size. If someone wants more power and xmit time in digital they can always buy a heatsink, and the cost of doing so is not added to the KX3 for 90% of the purchasers who do not need it.
More info on my website www.proaudioeng.com if you are interested, Howie - WA4PSC ______________________________________________________________ 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 Message delivered to [email protected]
