[Elecraft] Some "Cool" heat sink info.

[Johnny Siu]

Hello Howard,

Thanks for useful information in your web site www.proaudioeng.com which is interesting (the portable power supply for KX3 looks cool)

I must admit that English is my second language and sometimes I may not choose the right words.  I have no intention to bad mouth any specific design / R&D on KX3 heat sinks available in the commercial market.  In fact, I eventually bought a KB8UHN heat sink, which is a commercial product, for my KX3.  The heat sink suits my purpose of prolong operation in FM mode in 10/6m under full power.

As a ham, I trust some of them may like to do their own experiment in building their own heat sinks (since it is not a rocket science).  Doing experiment at a fraction of the cost could give some satisfaction to the investigating minds.

In my case, I did some experiment on fitting different 'amateur' heat sinks.  Clearly, the result was not that successful and I eventually settled down on a heat sink available from the commercial market.

I have been adopting that kind of 'experimenting' attitude for ham radio for years,  Sometimes, I succeed but there were many times when I completely failed.

The most successful experiment in my case is that I found a Panasonic boom headset at US$25 which gave me excellent audio reports so that I eventually sold all my Heils (no disgrace to Heil products).

73

Johnny VR2XMC

 
 寄件人︰ Howard Hoyt <hhoyt at mebtel.net>
收件人︰ elecraft at mailman.qth.net 
傳送日期︰ 2014年08月14日 (週四) 1:55 AM
主題︰ [Elecraft] Some "Cool" heat sink info.
  

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

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