Actually I (agree with Don) thought that it’s possibly the z bracket secured to the heat sink and the difference between the two expansions causing the abrupt shifts and resonating the fins.
Chuck Jack KE9UW Sent from my iPhone, cjack > On Jul 19, 2018, at 9:09 AM, Bob McGraw K4TAX <[email protected]> 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: [email protected] [[email protected]] >>> on behalf of Martin Sole [[email protected]] >>> Sent: Wednesday, July 18, 2018 8:37 PM >>> To: [email protected] >>> 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 >>>> ______________________________________________________________ >>>> 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] >>> ______________________________________________________________ >>> 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] >>> ______________________________________________________________ >>> 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] >> >> ______________________________________________________________ >> 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] > > > ______________________________________________________________ > 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] ______________________________________________________________ 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]
