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K3s+KPA500 SSB audio distortion

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K3s+KPA500 SSB audio distortion

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
[hidden email] <mailto:[hidden email]>

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Ignacy

Re: K3s+KPA500 SSB audio distortion

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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Jim Miller

Re: 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 <[hidden email]> 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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Elecraft mailing list

Re: K3s+KPA500 SSB audio distortion

In reply to this post by Elecraft mailing list

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 <[hidden email]> 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
> [hidden email] <mailto:[hidden email]>
>
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Elecraft mailing list

Re: K3s+KPA500 SSB audio distortion

In reply to this post by Elecraft mailing list

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 <[hidden email]> 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
> [hidden email] <mailto:[hidden email]>
>
>
>
>
>
>

ks4v@comcast.net

Re: K3s+KPA500 SSB audio distortion

In reply to this post by Jim Miller

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 <[hidden email]> Date: 8/1/18 10:42 AM (GMT-06:00) To: Ignacy <[hidden email]> Cc: [hidden email] 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 <[hidden email]> wrote:

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

--
Sent from: http://elecraft.365791.n2.nabble.com/
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Don Wilhelm

Re: K3s+KPA500 SSB audio distortion

In reply to this post by Elecraft mailing list

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, [hidden email] 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 <[hidden email]> Date: 8/1/18 10:42 AM (GMT-06:00) To: Ignacy <[hidden email]> Cc: [hidden email] 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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Elecraft mailing list

Re: K3s+KPA500 SSB audio distortion

In reply to this post by Elecraft mailing list

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, "[hidden email]" <[hidden email]> 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 <[hidden email]> Date: 8/1/18 10:42 AM (GMT-06:00) To: Ignacy <[hidden email]> Cc: [hidden email] 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 <[hidden email]> wrote:
>
> Could it be RF feedback? You can check it by transmitting into a dummy load
> or lowering the drive power.
> Ignacy, NO9E
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
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>
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>
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