Re: [Elecraft] K3s+KPA500 SSB Audio Distortion

[Michael Walker]

To be sure, your next test is to run the KPA500 into a dummy  load and
listen to yourself on another receiver.

This will help confirm if you have an equipment issue or an RFI issue.

It is critical to start with a very basic setup and work your way up to
more complicated.  K3 and a hand mic into a dummy load.  If that is ok,
then add the KPA500, etc.

Beyond that, you are can quickly be chasing your tail.

After all that and you add an antenna, and you have the problem, you have
to start dealing with common mode currents (aka RFI).  Start install chokes
(like Mix 41) on feedlines and powerlines.  Both ends.  At the antenna and
at the radio.

I read a document by the YCCC years ago and it became my bible on RF
issues.  The by product is that I started to hear more as I had less
receiver noise as well.

Let us know how you make out.

Mike va3mw






On Wed, Aug 1, 2018 at 10:03 PM, William C. Johnson via Elecraft <
elecraft@mailman.qth.net> wrote:

> Michael I also have the same problem. Worked on it with Elecraft Support
> several times to no avail.
> I have tried several different microphones, antennas, baluns. Still no
> joy. I also use 18 watts drive, I had not thought of anything other than rf
> feedback. I will play with different drive levels.In frustration I have
> quit using the KPA-500. I hope you are on to something.
> Bill J K7BRR Yuma
>
> Message: 2Date: Wed, 01 Aug 2018 10:19:04 -0400
> From: Michael Blake 
> To: Elecraft Mailing List 
> Subject: [Elecraft] K3s+KPA500 SSB audio distortion
> Message-ID: <312a3cd1-8c02-4b75-b39d-d93ecaf47...@mac.com>
> Content-Type: text/plain;charset=utf-8
>
> While on the air on 3710 SSB I receive audio reports that say my
> transmitted audio is somewhat muffled or nasal.  Making adjustments to mic
> gain, compression levels, TX EQ seems to make no difference to this report.
> These adjustments do change the sound of the audio but do not reduce the
> reports of muffled or nasal characteristics.
>
> I normally run the KPA500 at 500 watts PEP output and the K3s is set to 18
> watts to achieve this output.
>
> This morning I suspected that this nasal sound might be related to running
> the K3s at 18 watts as that uses both the 100 watt amplifier and the 12
> watt amplifier but in series at very low drive levels.  As a test I cut off
> the KPA500 and ran the K3s at 100 watts and the distortion was gone.  As a
> second test I dropped the drive to 11.9 watts which dropped off the 100
> watt amplifier module and runs the low power module at almost full power
> and the audio was still clean with the KPA500 delivering about 300 watts
> PEP.
>
> Is this something that anyone else has observed?  Are there any built in
> tests or adjustments that might help this issue?  I have run the
> transmitter gain calibration at all three power levels with satisfactory
> results.
>
> Oh yes,?.  The condition is the same using a dynamic mic (EV RE50), an
> Electret Mic (MH4 & CM500) or mic audio from a USB connected computer (Blue
> Yeti).
>
> Very 73 - Mike - K9JRI
>
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[Elecraft] K3s+KPA500 SSB Audio Distortion

[William C. Johnson via Elecraft]

Michael I also have the same problem. Worked on it with Elecraft Support 
several times to no avail. 
I have tried several different microphones, antennas, baluns. Still no joy. I 
also use 18 watts drive, I had not thought of anything other than rf feedback. 
I will play with different drive levels.In frustration I have quit using the 
KPA-500. I hope you are on to something.
Bill J K7BRR Yuma

Message: 2Date: Wed, 01 Aug 2018 10:19:04 -0400
From: Michael Blake 
To: Elecraft Mailing List 
Subject: [Elecraft] K3s+KPA500 SSB audio distortion
Message-ID: <312a3cd1-8c02-4b75-b39d-d93ecaf47...@mac.com>
Content-Type: text/plain;    charset=utf-8

While on the air on 3710 SSB I receive audio reports that say my transmitted 
audio is somewhat muffled or nasal.  Making adjustments to mic gain, 
compression levels, TX EQ seems to make no difference to this report. These 
adjustments do change the sound of the audio but do not reduce the reports of 
muffled or nasal characteristics.

I normally run the KPA500 at 500 watts PEP output and the K3s is set to 18 
watts to achieve this output.

This morning I suspected that this nasal sound might be related to running the 
K3s at 18 watts as that uses both the 100 watt amplifier and the 12 watt 
amplifier but in series at very low drive levels.  As a test I cut off the 
KPA500 and ran the K3s at 100 watts and the distortion was gone.  As a second 
test I dropped the drive to 11.9 watts which dropped off the 100 watt amplifier 
module and runs the low power module at almost full power and the audio was 
still clean with the KPA500 delivering about 300 watts PEP.

Is this something that anyone else has observed?  Are there any built in tests 
or adjustments that might help this issue?  I have run the transmitter gain 
calibration at all three power levels with satisfactory results.

Oh yes,?.  The condition is the same using a dynamic mic (EV RE50), an Electret 
Mic (MH4 & CM500) or mic audio from a USB connected computer (Blue Yeti).

Very 73 - Mike - K9JRI

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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[Michael Blake via Elecraft]

Bruce, Elecraft is replacing mine too. They came to that conclusion after 
directing me to make a few tests and report the results. 

73 - Mike - K9JRI


> On Aug 1, 2018, at 20:54, "k...@comcast.net"  wrote:
> 
> A local ham had the exact same problem. It was not a problem with his setup.  
> Elecraft replaced the PA board and the problem went away.BruceKS4V
>  Original message From: Jim Miller  
> Date: 8/1/18  10:42 AM  (GMT-06:00) To: Ignacy  Cc: 
> elecraft@mailman.qth.net Subject: Re: [Elecraft] K3s+KPA500 SSB audio 
> distortion 
> I ran my KPA500 for several years at 500w and often received unsolicited 
> “great audio” reports. CM500 was my headset. 
> 
> Something is wrong with your setup. 
> 
> Jim ab3cv (have kpa1500 now)
> 
> On Aug 1, 2018, at 11:09 AM, Ignacy  wrote:
> 
> Could it be RF feedback? You can check it by transmitting into a dummy load
> or lowering the drive power.
> Ignacy, NO9E  
> 
> 
> 
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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[Don Wilhelm]

If the problem is present with the K3 (without the KPA500) set to 50 to 
100 watts, then the KPA3 is the likely problem.
BUT if the K3 operated up to 100 watts does no have the problem, look 
for an RF in the Shack problem that may not be apparent at 100 watts, 
but 'rears its ugly head' at 500 watts output.


73,
Don W3FPR

On 8/1/2018 8:54 PM, k...@comcast.net wrote:

A local ham had the exact same problem. It was not a problem with his setup.  
Elecraft replaced the PA board and the problem went away.BruceKS4V
 Original message From: Jim Miller  Date: 
8/1/18  10:42 AM  (GMT-06:00) To: Ignacy  Cc: elecraft@mailman.qth.net 
Subject: Re: [Elecraft] K3s+KPA500 SSB audio distortion
I ran my KPA500 for several years at 500w and often received unsolicited “great 
audio” reports. CM500 was my headset.

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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[k...@comcast.net]

A local ham had the exact same problem. It was not a problem with his setup.  
Elecraft replaced the PA board and the problem went away.BruceKS4V
 Original message From: Jim Miller  Date: 
8/1/18  10:42 AM  (GMT-06:00) To: Ignacy  Cc: 
elecraft@mailman.qth.net Subject: Re: [Elecraft] K3s+KPA500 SSB audio 
distortion 
I ran my KPA500 for several years at 500w and often received unsolicited “great 
audio” reports. CM500 was my headset. 

Something is wrong with your setup. 

Jim ab3cv (have kpa1500 now)

On Aug 1, 2018, at 11:09 AM, Ignacy  wrote:

Could it be RF feedback? You can check it by transmitting into a dummy load
or lowering the drive power.
Ignacy, NO9E  



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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[Michael Blake via Elecraft]

Elecraft tech support suspects a bad KPA3A and has arranged for a module swap.

It is nice that you (me) can be so pleased even when you encounter a problem.  
Great company.

Very 73 - Mike - K9JRI






> On Aug 1, 2018, at 10:19 AM, Michael Blake  wrote:
> 
> While on the air on 3710 SSB I receive audio reports that say my transmitted 
> audio is somewhat muffled or nasal.  Making adjustments to mic gain, 
> compression levels, TX EQ seems to make no difference to this report. These 
> adjustments do change the sound of the audio but do not reduce the reports of 
> muffled or nasal characteristics.
> 
> I normally run the KPA500 at 500 watts PEP output and the K3s is set to 18 
> watts to achieve this output.
> 
> This morning I suspected that this nasal sound might be related to running 
> the K3s at 18 watts as that uses both the 100 watt amplifier and the 12 watt 
> amplifier but in series at very low drive levels.  As a test I cut off the 
> KPA500 and ran the K3s at 100 watts and the distortion was gone.  As a second 
> test I dropped the drive to 11.9 watts which dropped off the 100 watt 
> amplifier module and runs the low power module at almost full power and the 
> audio was still clean with the KPA500 delivering about 300 watts PEP.
> 
> Is this something that anyone else has observed?  Are there any built in 
> tests or adjustments that might help this issue?  I have run the transmitter 
> gain calibration at all three power levels with satisfactory results.
> 
> Oh yes,….  The condition is the same using a dynamic mic (EV RE50), an 
> Electret Mic (MH4 & CM500) or mic audio from a USB connected computer (Blue 
> Yeti).
> 
> Very 73 - Mike - K9JRI
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Michael Blake
> k9...@mac.com 
> 
> 
> 
> 
> 
> 

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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[Jack Brindle via Elecraft]

How are they connected? (i.e. are you using the AuxIO cable?) Do you have ALC 
turned on in the K3?

73!
Jack, W6FB

> On Aug 1, 2018, at 7:19 AM, Michael Blake via Elecraft 
>  wrote:
> 
> While on the air on 3710 SSB I receive audio reports that say my transmitted 
> audio is somewhat muffled or nasal.  Making adjustments to mic gain, 
> compression levels, TX EQ seems to make no difference to this report. These 
> adjustments do change the sound of the audio but do not reduce the reports of 
> muffled or nasal characteristics.
> 
> I normally run the KPA500 at 500 watts PEP output and the K3s is set to 18 
> watts to achieve this output.
> 
> This morning I suspected that this nasal sound might be related to running 
> the K3s at 18 watts as that uses both the 100 watt amplifier and the 12 watt 
> amplifier but in series at very low drive levels.  As a test I cut off the 
> KPA500 and ran the K3s at 100 watts and the distortion was gone.  As a second 
> test I dropped the drive to 11.9 watts which dropped off the 100 watt 
> amplifier module and runs the low power module at almost full power and the 
> audio was still clean with the KPA500 delivering about 300 watts PEP.
> 
> Is this something that anyone else has observed?  Are there any built in 
> tests or adjustments that might help this issue?  I have run the transmitter 
> gain calibration at all three power levels with satisfactory results.
> 
> Oh yes,….  The condition is the same using a dynamic mic (EV RE50), an 
> Electret Mic (MH4 & CM500) or mic audio from a USB connected computer (Blue 
> Yeti).
> 
> Very 73 - Mike - K9JRI
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Michael Blake
> k9...@mac.com 
> 
> 
> 
> 
> 
> 
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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[Jim Miller]

I ran my KPA500 for several years at 500w and often received unsolicited “great 
audio” reports. CM500 was my headset. 

Something is wrong with your setup. 

Jim ab3cv (have kpa1500 now)

On Aug 1, 2018, at 11:09 AM, Ignacy  wrote:

Could it be RF feedback? You can check it by transmitting into a dummy load
or lowering the drive power.
Ignacy, NO9E  



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Re: [Elecraft] K3s+KPA500 SSB audio distortion

[Ignacy]

Could it be RF feedback? You can check it by transmitting into a dummy load
or lowering the drive power.
Ignacy, NO9E  



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[Elecraft] K3s+KPA500 SSB audio distortion

[Michael Blake via Elecraft]

While on the air on 3710 SSB I receive audio reports that say my transmitted 
audio is somewhat muffled or nasal.  Making adjustments to mic gain, 
compression levels, TX EQ seems to make no difference to this report. These 
adjustments do change the sound of the audio but do not reduce the reports of 
muffled or nasal characteristics.

I normally run the KPA500 at 500 watts PEP output and the K3s is set to 18 
watts to achieve this output.

This morning I suspected that this nasal sound might be related to running the 
K3s at 18 watts as that uses both the 100 watt amplifier and the 12 watt 
amplifier but in series at very low drive levels.  As a test I cut off the 
KPA500 and ran the K3s at 100 watts and the distortion was gone.  As a second 
test I dropped the drive to 11.9 watts which dropped off the 100 watt amplifier 
module and runs the low power module at almost full power and the audio was 
still clean with the KPA500 delivering about 300 watts PEP.

Is this something that anyone else has observed?  Are there any built in tests 
or adjustments that might help this issue?  I have run the transmitter gain 
calibration at all three power levels with satisfactory results.

Oh yes,….  The condition is the same using a dynamic mic (EV RE50), an Electret 
Mic (MH4 & CM500) or mic audio from a USB connected computer (Blue Yeti).

Very 73 - Mike - K9JRI









Michael Blake
k9...@mac.com 






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