[Elecraft] KPA500 thermal clicks

[Clay Autery]

I've solved many an issue with the stuff... Mostly IS/IT related...  
building for low sound, high-durability/longevity, but there are many 
applications... especially when you start molding it around fasteners...
I've used it in shotgun pads, running shoes, and bicycle seat pads...  
happy on all accounts.... but it is at its best when it is used to 
isolate/interrupt metallic vibration loops.

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 19-Jul-18 09:08, Bob McGraw K4TAX wrote:
> Well I really don't have an issue with mine but I did search and learn 
> about using a Sorbothane damper.   Interesting stuff and related 
> applications.
>
> 73
>
> Bob, K4TAX
>
>
> On 7/19/2018 9:01 AM, Clay Autery wrote:
>> Y'all are making me want to find a unit with this "issue" now just so 
>> I can solve the mystery....
>>
>> IF it is the aluminum fins "creaking" due to rapid thermal 
>> expansion/contraction, one possible/probably solution is a small 
>> Sorbothane damper attached across the fins in an appropriate 
>> spot....  Can likely be don without measurably challenging the 
>> airflow...
>>
>> 73,
>>
>> ______________________
>> Clay Autery, KY5G
>> (318) 518-1389
>>
>> On 19-Jul-18 08:18, hawley, charles j jr wrote:
>>> The ticking sound is clearly the resonant aluminum heat sink fins. 
>>> The mechanical shrinking or expanding is abrupt and resonates the 
>>> fins much like a tuning fork.
>>> My take on it...
>>>
>>> Chuck
>>> Amateur Radio, KE9UW
>>> _____
>>> From: elecraft-bounces at mailman.qth.net 
>>> [elecraft-bounces at mailman.qth.net] on behalf of Martin Sole 
>>> [hs0zed at gmail.com]
>>> Sent: Wednesday, July 18, 2018 8:37 PM
>>> To: elecraft at mailman.qth.net
>>> Subject: Re: [Elecraft] KPA500 thermal clicks
>>>
>>> I think it sounds "orrible!". I'm quite used to the low rumble of the
>>> blower in my Alpha 77D but that ticking would be like Chinese water
>>> torture to me. Listening to an individual tick it does seem to have a
>>> ring to it. Okay the recording was perhaps not the most acoustically
>>> perfect but it certainly does sound as if the ring is from the source
>>> and not any sort of artifact. If it is from the source then I think you
>>> can probably find a way to damp it. First trick will be to identify the
>>> specific source.
>>>
>>> I had read other comments about a ticking, always imagined it to be
>>> minimal and essentially unobtrusive but if what you have recorded is
>>> anything like how it sounds sat in front of it then definitely it does
>>> sound pretty bad to me and not just in amplitude but also in its 
>>> timbre,
>>> pitch, and repetition rate.
>>>
>>> Martin, HS0ZED
>>>
>>>
>>> On 19/07/2018 06:25, ANDY DURBIN wrote:
>>>> I placed my Android phone on top of my KPA500 and made a recording 
>>>> while making a few cycles of FT8 TX/RX.  The audio files can be 
>>>> found here:
>>>>
>>>> https://www.dropbox.com/sh/amfy3dz8pgl083n/AAAKi2GYripXyIDjiLpJ2hDwa?dl=0 
>>>>
>>>>
>>>>
>>>> One file is the raw recording.  The second has been processed in 
>>>> Audacity to amplify to 0 dB peak.  The file starts before the first 
>>>> TX. Next the hum of the transformer can be heard with FT8 
>>>> modulation in the background from TX moni.   As the recording 
>>>> progresses the changes in fan speed can be heard. The click are 
>>>> always well above the fan noise.
>>>>
>>>> I used this recording to perform some spectral analysis of the 
>>>> clicks.  I took one sample at the click and another sample of the 
>>>> noise just before the click.  I then subtracted the noise from the 
>>>> click and I think I have a reasonable click signature to use as a 
>>>> baseline for evaluating any mechanical changes I make in an attempt 
>>>> to reduce the clicks.
>>>>
>>>> Crank it up and enjoy, especially if you think it's normal.
>>>>
>>>> 73,
>>>> Andy k3wyc
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