[Elecraft] [KX3] A Comparative Performance Assessment (of Aftermarket KX3 Heatsinks)

[Dennis Griffin]

I too had to wonder about a few of the report comments.

At what distance from the KX3 was the "still air" temperature taken, and how was it maintained within plus or minus .5° C if it was still, but in fact was being acted on by the convective currents caused by the heat radiated by the heat sink. Certainly the room may have held temp within that tolerance, but surely the air immediately around the heat sink didn't.

Was the still air around the KX3 allowed to normalize between tests, or was each successive test performed in an increasingly warmer envelop of air immediately around the test unit?

What instrument was used for the air temp measurement to a resolution of at least .5° C, that couldn't also have been used to measure the temperature at some fixed point relative to the heat sinks, whether it reported NIST accurate values, or only just relative and repeatable values. Since the temp reported by the KX3 only has 1° C of resolution, I can see the potential to have a .9° C margin of error in reported values, or a .1° C actual difference leading to a reported 1° C difference.

How representative is 25° C as an ambient operating temperature for someone who feels the need for the benefit of a heat sink? Probably close enough for someone operating in their shack. But how do the results translate to any noted differences when operating portable at 0° C, or 37° C, or at 25° C & 90% RH?

Fine points, admittedly, but curiosities none the less.

73 de Dennis KD7CAC
Scottsdale, AZ

On Sep 2, 2014, at 11:39 AM, Don Wilhelm <w3fpr at embarqmail.com> wrote:

> That is true, but that is still inadequate information for environmentally related measurements.
> Exactly how was that measured?  What was the measurement device, when was it last calibrated, was the calibration traceable to a secondary NIST standard?  Was the point where the temperature was measured identified and consistent from test to test?  How were the initial conditions determined?  Within what degree of certainty? Was the air flow actually monitored during the test and from test run to test run - how was it measured and at what position(s) - why does still air have to be in quotes? Without that kind information, we have to make assumptions that may or may not be valid.
> 
> Making system level measurements on environmentally related tests requires that every piece of the environment be specified - down to the placement of the DUT in the environment.
> 
> My 10 years professional experience with engineering level measurements has lead me to question every piece of test equipment as well as how it is used as well as identification of the test setup.
> That information is important to determine that degree of error in the overall measurements.
> Environmental testing requires much more setup and environment data than making voltage checks because there are many factors that may alter the data.
> 
> 73,
> Don W3FPR
> 
> On 9/2/2014 1:55 PM, Gary W. Hvizdak wrote:
>> P.S.  Don, Adrian's test report clearly states that he conducted all of his
>> tests in "still air" and that the ambient temperature remained between a
>> half degree of 25 degrees C.