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KPA500 thermal clicks

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123

Wes Stewart-2

OT: Weak Signal v. Low Power

In deference to the OP in the KPA500 clicking thread...

Having once operated EME (on CW) and meteor and tropo scatter, I can say that
terrestrial path loss is not necessarily lower than the EME path. Many years
ago, W7UBI (SK) in Boise, ID and I ran twice-weekly two-meter MS schedules for
over a year. We both had EME capable stations. The distance between up was
about 850 miles, an easy MS distance but extreme for tropo. If memory serves,
our rate of completion of valid MS QSOs was in the neighborhood of 30-35%. But
what was interesting was that there were times when residual (tropo) signals
were readable. The point is that for either terrestrial mode, high power was
both appropriate and necessary. I should add that in addition to path loss,
terrestrial noise is also an issue to be overcome.

As to the broad (wide) signals, those are not necessarily caused by strong
signals but weak receivers.

Wes N7WS

On 7/17/2018 8:59 AM, turnbull wrote:

> EME boys fave a lot of patb loss and their Yagis point to the moon. For terrestrial worm, the path loss is generally much lower and especially when there are othdf local hams or good propagation the signal levels can be high. This often leads to excessively wide signals on different audio frequencies.
>
>
> Sent from my Samsung Galaxy smartphone.
> -------- Original message --------From: "Dave Cole (NK7Z)" <[hidden email]> Date: 17/07/2018 15:30 (GMT+00:00) To: [hidden email] Subject: Re: [Elecraft] KPA500 thermal clicks
> yes... Weak Signal, not low power. The EME boys use 1 KW.
>
> 73s and thanks,
> Dave
> NK7Z
> https://www.nk7z.net

Jim Brown-10

FT8 and Strong Signals

In reply to this post by Doug Turnbull

On 7/17/2018 8:52 AM, turnbull wrote:
> I agree but many people are suffering from wide FT8 signals from others with strong signals.

Part of this is perception rather than reality -- a failure to
understand the waterfall display. Because the waterfall displays both
signal strength and spectrum, a very strong signal may APPEAR to be
broader than it really is. I have a half dozen or so neighbors running
FT8 on 6M within about 15 miles, and all are running a power amp (mostly
KPA500, but my closest neighbor, about 5 miles, runs 1.3kW. Most of us
are running K3s. It's not uncommon for one of these signals to SEEM to
occupy 500 Hz or more, the reality is that I often decode weak signals
within that 500 Hz.

Another point. K1JT recommends setting audio level into the computer for
an indicated 30 dB on the bar graph. I think this is part of the problem
caused by strong signals taking over the AGC and greatly reducing the
gain. If, for example, a local who's 30 dB over S9, reduces the RF gain
by 30 dB, an S9 signal would be below the level of the sound card! I set
audio level into the computer for the highest level that doesn't flash
RED (indicating digital clip) on strong signals. My bar graph typically
runs 50-60 dB. With this setting, even when AGC has reduce the gain by
30 dB or more, weak signals are still well above the "bottom" of the A/D
converter, and are decoded just fine.

73, Jim K9YC

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Doug Turnbull

Re: FT8 and Strong Signals

Jim, Thank you for the solid information.
73 Doug EI2CN
PS I understand AGC should be disabled.

Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: Jim Brown <[hidden email]> Date: 17/07/2018 18:51 (GMT+00:00) To: [hidden email] Subject: [Elecraft] FT8 and Strong Signals
On 7/17/2018 8:52 AM, turnbull wrote:
> I agree but many people are suffering from wide FT8 signals from others with strong signals.

Part of this is perception rather than reality -- a failure to
understand the waterfall display. Because the waterfall displays both
signal strength and spectrum, a very strong signal may APPEAR to be
broader than it really is. I have a half dozen or so neighbors running
FT8 on 6M within about 15 miles, and all are running a power amp (mostly
KPA500, but my closest neighbor, about 5 miles, runs 1.3kW. Most of us
are running K3s. It's not uncommon for one of these signals to SEEM to
occupy 500 Hz or more, the reality is that I often decode weak signals
within that 500 Hz.

Another point. K1JT recommends setting audio level into the computer for
an indicated 30 dB on the bar graph. I think this is part of the problem
caused by strong signals taking over the AGC and greatly reducing the
gain. If, for example, a local who's 30 dB over S9, reduces the RF gain
by 30 dB, an S9 signal would be below the level of the sound card! I set
audio level into the computer for the highest level that doesn't flash
RED (indicating digital clip) on strong signals. My bar graph typically
runs 50-60 dB. With this setting, even when AGC has reduce the gain by
30 dB or more, weak signals are still well above the "bottom" of the A/D
converter, and are decoded just fine.

73, Jim K9YC

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Bob McGraw - K4TAX

Re: FT8 and Strong Signals

Thanks Jim, K9YC, for the detailed information. I too concur that wide
signals can more likely be the result of the waterfall adjustments, or
the system gain, which has the no signal noise level above 30 dB on the
WSJT-X bargraph indicator. If this is the case, adjust the audio level
in the Windows application to reduce the level.

As to AGC, I run AGC on my K3S on Fast when operating FT-8. Likewise for
CW. Thus I've found no disadvantage in having it on, and little to no
advantage in having it off. Other than I manually have to adjust RF gain.

On that note, for the most part on 160 M, 80 M & 40 M I do run 15 dB to
10 dB of Attenuation and back the RF Gain down accordingly. For higher
frequencies, 60 M and above, I do not use Attenuation and adjust the RF
gain accordingly. This seems to produce optimum receiver performance.
On 6 M I do engage the preamp.

73

Bob, K4TAX

On 7/17/2018 12:59 PM, turnbull wrote:

> Jim, Thank you for the solid information.
> 73 Doug EI2CN
> PS I understand AGC should be disabled.
>
>
> Sent from my Samsung Galaxy smartphone.
> -------- Original message --------From: Jim Brown <[hidden email]> Date: 17/07/2018 18:51 (GMT+00:00) To: [hidden email] Subject: [Elecraft] FT8 and Strong Signals
> On 7/17/2018 8:52 AM, turnbull wrote:
>> I agree but many people are suffering from wide FT8 signals from others with strong signals.
> Part of this is perception rather than reality -- a failure to
> understand the waterfall display. Because the waterfall displays both
> signal strength and spectrum, a very strong signal may APPEAR to be
> broader than it really is. I have a half dozen or so neighbors running
> FT8 on 6M within about 15 miles, and all are running a power amp (mostly
> KPA500, but my closest neighbor, about 5 miles, runs 1.3kW. Most of us
> are running K3s. It's not uncommon for one of these signals to SEEM to
> occupy 500 Hz or more, the reality is that I often decode weak signals
> within that 500 Hz.
>
> Another point. K1JT recommends setting audio level into the computer for
> an indicated 30 dB on the bar graph. I think this is part of the problem
> caused by strong signals taking over the AGC and greatly reducing the
> gain. If, for example, a local who's 30 dB over S9, reduces the RF gain
> by 30 dB, an S9 signal would be below the level of the sound card! I set
> audio level into the computer for the highest level that doesn't flash
> RED (indicating digital clip) on strong signals. My bar graph typically
> runs 50-60 dB. With this setting, even when AGC has reduce the gain by
> 30 dB or more, weak signals are still well above the "bottom" of the A/D
> converter, and are decoded just fine.
>
> 73, Jim K9YC
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Doug Turnbull

Re: FT8 and Strong Signals

Thank you Bob and Jim for the useful observations.
73 Doug EI2CN

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Bob McGraw K4TAX
Sent: 17 July 2018 18:11
To: [hidden email]
Subject: Re: [Elecraft] FT8 and Strong Signals

Thanks Jim, K9YC, for the detailed information. I too concur that wide
signals can more likely be the result of the waterfall adjustments, or
the system gain, which has the no signal noise level above 30 dB on the
WSJT-X bargraph indicator. If this is the case, adjust the audio level
in the Windows application to reduce the level.

As to AGC, I run AGC on my K3S on Fast when operating FT-8. Likewise for
CW. Thus I've found no disadvantage in having it on, and little to no
advantage in having it off. Other than I manually have to adjust RF gain.

On that note, for the most part on 160 M, 80 M & 40 M I do run 15 dB to
10 dB of Attenuation and back the RF Gain down accordingly. For higher
frequencies, 60 M and above, I do not use Attenuation and adjust the RF
gain accordingly. This seems to produce optimum receiver performance.
On 6 M I do engage the preamp.

73

Bob, K4TAX

On 7/17/2018 12:59 PM, turnbull wrote:
> Jim, Thank you for the solid information.
> 73 Doug EI2CN
> PS I understand AGC should be disabled.
>
>
> Sent from my Samsung Galaxy smartphone.
> -------- Original message --------From: Jim Brown
<[hidden email]> Date: 17/07/2018 18:51 (GMT+00:00) To:
[hidden email] Subject: [Elecraft] FT8 and Strong Signals
> On 7/17/2018 8:52 AM, turnbull wrote:
>> I agree but many people are suffering from wide FT8 signals from others
with strong signals.

> Part of this is perception rather than reality -- a failure to
> understand the waterfall display. Because the waterfall displays both
> signal strength and spectrum, a very strong signal may APPEAR to be
> broader than it really is. I have a half dozen or so neighbors running
> FT8 on 6M within about 15 miles, and all are running a power amp (mostly
> KPA500, but my closest neighbor, about 5 miles, runs 1.3kW. Most of us
> are running K3s. It's not uncommon for one of these signals to SEEM to
> occupy 500 Hz or more, the reality is that I often decode weak signals
> within that 500 Hz.
>
> Another point. K1JT recommends setting audio level into the computer for
> an indicated 30 dB on the bar graph. I think this is part of the problem
> caused by strong signals taking over the AGC and greatly reducing the
> gain. If, for example, a local who's 30 dB over S9, reduces the RF gain
> by 30 dB, an S9 signal would be below the level of the sound card! I set
> audio level into the computer for the highest level that doesn't flash
> RED (indicating digital clip) on strong signals. My bar graph typically
> runs 50-60 dB. With this setting, even when AGC has reduce the gain by
> 30 dB or more, weak signals are still well above the "bottom" of the A/D
> converter, and are decoded just fine.
>
> 73, Jim K9YC
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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ANDY DURBIN

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

"I'd appreciate a pointer to any discussions of Z bracket clicks. My search didn't find anything."

I looked again and this time found some discussion here - https://forums.qrz.com/index.php?threads/elecraft-kpa500-pinging-during-operating.591521/ and here - http://elecraft.365791.n2.nabble.com/KPA500-Heat-Expansion-Pop-td7075132.html.

Reading between the lines I get the impression Elecraft tried to fix the problem, found they had not, so wrote in the manual that it is normal.

I'd still like an answer to the question I asked April 21, 2018 -

"To what extend does the thermal design require conduction between the PA heat sink and the case metalwork? Would the thermal management be compromised if very thin mylar strips were placed between the heat sink and the case side panel , case rear panel, or Z bracket?".

Would someone at Elecraft please respond to this.
Thanks and 73,
Andy k3wyc

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Buck

Re: KPA500 thermal clicks

I noticed the clicks when the amp was new. Advice was to re-seat the
toroid transformer. That made no difference but the clicks have gone
away. I assume the transformer settled in, if such a thing is possible.

Buck, k4ia
Honor Roll
8BDXCC
EasyWayHamBooks.com

On 7/17/2018 5:37 PM, ANDY DURBIN wrote:

> "I'd appreciate a pointer to any discussions of Z bracket clicks. My search didn't find anything."
>
>
> I looked again and this time found some discussion here - https://forums.qrz.com/index.php?threads/elecraft-kpa500-pinging-during-operating.591521/ and here - http://elecraft.365791.n2.nabble.com/KPA500-Heat-Expansion-Pop-td7075132.html.
>
>
> Reading between the lines I get the impression Elecraft tried to fix the problem, found they had not, so wrote in the manual that it is normal.
>
>
> I'd still like an answer to the question I asked April 21, 2018 -
>
> "To what extend does the thermal design require conduction between the PA heat sink and the case metalwork? Would the thermal management be compromised if very thin mylar strips were placed between the heat sink and the case side panel , case rear panel, or Z bracket?".
>
> Would someone at Elecraft please respond to this.
> Thanks and 73,
> Andy k3wyc
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
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ANDY DURBIN

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

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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Elecraft mailing list

Re: KPA500 thermal clicks

Andy, mine sounds very much like your recording. When on FT8 and using the KPA500 I usually set its fan to 2 and it seldom ramps up past that speed.

Your recording sounds very normal to me. Maybe not a good thing but normal :)

73 - Mike - K9JRI

> On Jul 18, 2018, at 7:25 PM, ANDY DURBIN <[hidden email]> 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
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> Message delivered to [hidden email]

Bob McGraw - K4TAX

Re: KPA500 thermal clicks

Yep, mine sounds about the same. And I too run the fan on #2 when
working FT-8. Otherwise, I set it to normal and it cycles on and off as
needed. The clicks and pops are considered "normal" as per the KPA-500
manual and also a friend that was instrumental in me making my
purchase. Fact of the matter, the static crashes are louder than the
amp clicks.

I have acoustic material on the wall behind the amp. That absorbs a lot
of sound that would normally be reflected into the room, both from the
fan and from the clicks.

73

Bob, K4TAX

On 7/18/2018 6:45 PM, Michael Blake via Elecraft wrote:

> Andy, mine sounds very much like your recording. When on FT8 and using the KPA500 I usually set its fan to 2 and it seldom ramps up past that speed.
>
> Your recording sounds very normal to me. Maybe not a good thing but normal :)
>
> 73 - Mike - K9JRI
>
>
>
>
>
>
>
>> On Jul 18, 2018, at 7:25 PM, ANDY DURBIN <[hidden email]> 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:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
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ke9uw

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

I definitely never heard that

Chuck Jack
KE9UW

Sent from my iPhone, cjack

> On Jul 18, 2018, at 6:26 PM, ANDY DURBIN <[hidden email]> 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
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>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Chuck, KE9UW

Martin Sole-3

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

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
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Bob McGraw - K4TAX

Re: KPA500 thermal clicks

All of these "relative" recordings have little to no value in terms of
"how loud" the noise may be.   Yes, it is there. Amplify it enough and
it will blow the side of the house out. The phone on top of the amp is
certainly not where ones ear may reside.

If one wishes to cite how loud a sound exists, then use a sound level
meter and measure the noise at a specific and stated distance and
several different axis and report the level in dB. A weighted or C
weighted.   Also measure and state the level of the room ambient.    Use
a spectrum analyzer to quantify the nature or content of the sound,
frequency and waveform.   Those numbers will then equate to something
that is meaningful.   If others do the same, then there is contained
evidence of units which may contribute to the artifact of concern.

73

Bob, K4TAX

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Randy Farmer

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

I have never heard anything like that on my early kit-assembled KPA500.
But... I've only used it extensively on CW. It would be interesting to
know if the clicks are being experienced only under high duty cycle
usage such as digital modes or if they have also been heard in CW/SSB duty.

73...
Randy, W8FN

On 7/18/2018 6:25 PM, 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

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Martin Sole-3

Re: KPA500 thermal clicks

In reply to this post by Bob McGraw - K4TAX

I think a more realistic measurement than the original, phone on the amp
cabinet would be to place the phone on something like a tripod roughly
where the operators head might be. That is likely to be a more balanced
level.

That said I'm not sure that having the specific absolute level in one
particular environment is necessarily all that useful, in this case.
Having a number, defined in specific terms doesn't help me to feel one
way or the other if that would impact on my operating. But if I can hear
what Andy hears and it sounds anything like what he recorded then I
would be looking at ways to mitigate it. Recording and amplifying the
offending sound as much as necessary in order to identify the root would
seem a good start.

What Andy showed is that there is a ticking sound and that sound is
being produced by an action on one or more materials. If they can be
identified it is possible that sound can be reduced. Whetherit is a loud
or quiet sound is of less significance, we all hear differently.

Martin, HS0ZED

On 19/07/2018 09:31, Bob McGraw K4TAX wrote:

> All of these "relative" recordings have little to no value in terms of
> "how loud" the noise may be.   Yes, it is there. Amplify it enough and
> it will blow the side of the house out. The phone on top of the amp
> is certainly not where ones ear may reside.
>
> If one wishes to cite how loud a sound exists, then use a sound level
> meter and measure the noise at a specific and stated distance and
> several different axis and report the level in dB. A weighted or C
> weighted.   Also measure and state the level of the room ambient.
> Use a spectrum analyzer to quantify the nature or content of the
> sound, frequency and waveform.   Those numbers will then equate to
> something that is meaningful.   If others do the same, then there is
> contained evidence of units which may contribute to the artifact of
> concern.
>
> 73
>
> Bob, K4TAX
>
>
>
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Jim Sheldon

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

I've had my KPA500 for a few years now. I built it from a kit. The only time I ever hear what you describe is when I've been long winded on RTTY.

I run it @ 450 Watts out no matter the mode and I never even get a fan speed increase unless I'm in a RTTY rag chew and normally never hear any thermal clicks.

I don't worry about it or let it bother me.

Jim, W0EB

> On Jul 18, 2018, at 9:38 PM, Randy Farmer <[hidden email]> wrote:
>
> I have never heard anything like that on my early kit-assembled KPA500. But... I've only used it extensively on CW. It would be interesting to know if the clicks are being experienced only under high duty cycle usage such as digital modes or if they have also been heard in CW/SSB duty.
>
> 73...
> Randy, W8FN
>
>> On 7/18/2018 6:25 PM, 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
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Please help support this email list: http://www.qsl.net/donate.html
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ANDY DURBIN

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

"I doubt that a phone recording has the proper range to qualify as a test device."

I think some people have misunderstood the reason for making the recording. The purpose was to establish a baseline. If any mechanical changes I make change the acoustic signature of the clicks then I have increased my knowledge of what causes them. It does not matter a bit if what the phone records represents what I hear.

I do not claim that the phone recording is an absolute measurement of anything.

73,

Andy, k3wyc
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Gary Smith-2

Re: KPA500 thermal clicks - dB meter

In reply to this post by Bob McGraw - K4TAX

You can get a very nice dB meter in your
smart phone with several free apps. The
only caveat is it will only effectively
register 80 dB even though the scale
appears to read higher. This intensity
level is due to audio limiting circuitry
in the phone itself. I do have a hand held
dB meter that is accurate to 120 dB but I
rarely am around that noise level.

73,

Gary
KA1J

<snip>

> If one wishes to cite how loud a sound exists, then use a sound level
> meter and measure the noise at a specific and stated distance and
> several different axis and report the level in dB. A weighted or C
> weighted.   Also measure and state the level of the room ambient.
>    Use a spectrum analyzer to quantify the nature or content of the
> sound, frequency and waveform.   Those numbers will then equate to
> something that is meaningful.   If others do the same, then there is
> contained evidence of units which may contribute to the artifact of
> concern.
>
> 73
>
> Bob, K4TAX

john@kk9a.com

Re: KPA500 thermal clicks

In reply to this post by ANDY DURBIN

Nice documentation. My KPA500 also makes this clicking noise so I would
say that your amp is functioning normally. Apparently many people on this
list do not find it objectionable. My KPA500 is just a backup / casual use
amp but I would still send it in if there was a mod to fix this. I wonder
if the KPA1500 also clicks?

Back to the vanity callsign net...

John KK9A

ANDY DURBIN K3WYC 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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Edward A. Dauer

KPA500 Thermal Clicks

In reply to this post by ANDY DURBIN

Likewise. I have run mine (kit built) for years, mostly in contests, and never heard anything at all like that. I have heard a rapid series of low-volume clicks, lasting a few seconds, when I shut the amp off after a session but never a click while it's running. OTOH I do not use data modes - almost all CW and rarely SSB. Those clicks may be "normal" in the sense that others have it as well, but I would think there's a construction flaw somewhere . . . Can you isolate the source more precisely?

Ted, KN1CBR

------------------------------

Message: 21
Date: Wed, 18 Jul 2018 21:38:24 -0500
From: Randy Farmer <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] KPA500 thermal clicks
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8; format=flowed

I have never heard anything like that on my early kit-assembled KPA500.
But... I've only used it extensively on CW. It would be interesting to
know if the clicks are being experienced only under high duty cycle
usage such as digital modes or if they have also been heard in CW/SSB duty.

73...
Randy, W8FN

On 7/18/2018 6:25 PM, 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

------------------------------

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123