It would be interesting to follow the temp rise profile with the ticking.
Since the ticking continues over different operating conditions, it is hard to
tell if the overall ticking is tracking the temp. Seems to sound the same
throughout.. I don't like it at all. Too much thermal resistance
differential. Not good..
Mel, K6KBE
From: Martin Sole <hs0...@gmail.com>
To: elecraft@mailman.qth.net
Sent: Thursday, July 19, 2018 8:45 AM
Subject: Re: [Elecraft] KPA500 thermal clicks
I'm of the same mind, though a KPA1500 is more my preference to replace
one of the aging tube monsters here.
Good stuff Sorbothane.
Sorbothane was specifically designed for shock absorption
<https://www.sorbothane.com/what-is-a-good-material-for-shock-absorption.aspx>
and is manufactured to outperform every other material on the market.
What makes Sorbothane the best material for shock absorption?
* It absorbs more than 90% of shock energy and more than 50% of
vibration energy;
* It performs in temperatures ranging from –20° to 160° Fahrenheit
(–29° to 72° Celsius)];
* It performs at frequencies ranging from 10 to 30,000 Hertz;
* It’s damping ratio is 0.344 at 2.34 HZ;
* It doesn’t support bacterial or fungal growth and is relatively
unaffected by industrial solvents such as diesel fuel, kerosene, and
hydraulic fluid;
* It has an extremely long shelf life; and
* It has a superior damping coefficient.
But I wonder about that temp rating :-)
On 19/07/2018 21:01, 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-boun...@mailman.qth.net
>> [elecraft-boun...@mailman.qth.net] on behalf of Martin Sole
>> [hs0...@gmail.com]
>> Sent: Wednesday, July 18, 2018 8:37 PM
>> To: elecraft@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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