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: [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
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