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RF in Microphone

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Jim Kutsch, KY2D-2

RF in Microphone

I am a new K3S owner and very pleased. However, on SSB, I am getting reports
that my audio is distorted sounding like RF is getting into the microphone.
I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
had some RF microphone issues earlier using the PR-781 with a KX3 but a
better shielded mic cable and a common mode choke resolved it. Any
suggestions before I go in search of a different mic? Also, any
recommendations for a boom mount microphone that would be a better choice
for the K3S than this PR-781?

Thanks and 73, Jim, KY2D

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Jerry Moore

Re: RF in Microphone

What is your antenna setup and all connections between your k3s and the antenna?

Sent via the Samsung GALAXY S® 5, an AT&T 4G LTE smartphone

-------- Original message --------
From: Jim Kutsch <[hidden email]>
Date: 3/26/17 12:31 (GMT-05:00)
To: [hidden email]
Subject: [Elecraft] RF in Microphone

I am a new K3S owner and very pleased. However, on SSB, I am getting reports
that my audio is distorted sounding like RF is getting into the microphone.
I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
had some RF microphone issues earlier using the PR-781 with a KX3 but a
better shielded mic cable and a common mode choke resolved it. Any
suggestions before I go in search of a different mic? Also, any
recommendations for a boom mount microphone that would be a better choice
for the K3S than this PR-781?

Thanks and 73, Jim, KY2D

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Don Wilhelm

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

Jim,

I would suggest that you first try to reduce the RF coming into the
shack. Do a little work on your antennas - better baluns for instance,
and make sure all antenna connections are tight. Refer to Jim Brown
K9YC's paper at http://audiosystemsgroup.com/RFI-Ham.pdf for assistance.

73,
Don W3FPR

On 3/26/2017 12:31 PM, Jim Kutsch wrote:
> I am a new K3S owner and very pleased. However, on SSB, I am getting reports
> that my audio is distorted sounding like RF is getting into the microphone.
> I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
> had some RF microphone issues earlier using the PR-781 with a KX3 but a
> better shielded mic cable and a common mode choke resolved it. Any
> suggestions before I go in search of a different mic? Also, any
> recommendations for a boom mount microphone that would be a better choice
> for the K3S than this PR-781?
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Michael Walker

Re: RF in Microphone

Also,

Have a read on the YCCC's notes on chokes.

http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf

Not only will it help with RF issues on transmit, it will help all all the
noise in your shack and allow you to hear better.

I bought a case of Mix 43 chokes, and I've used them all. Worth every
penny.

Mike va3mw

On Sun, Mar 26, 2017 at 12:50 PM, Don Wilhelm <[hidden email]>
wrote:

> Jim,
>
> I would suggest that you first try to reduce the RF coming into the
> shack. Do a little work on your antennas - better baluns for instance, and
> make sure all antenna connections are tight. Refer to Jim Brown K9YC's
> paper at http://audiosystemsgroup.com/RFI-Ham.pdf for assistance.
>
> 73,
> Don W3FPR
>
> On 3/26/2017 12:31 PM, Jim Kutsch wrote:
>
>> I am a new K3S owner and very pleased. However, on SSB, I am getting
>> reports
>> that my audio is distorted sounding like RF is getting into the
>> microphone.
>> I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
>> had some RF microphone issues earlier using the PR-781 with a KX3 but a
>> better shielded mic cable and a common mode choke resolved it. Any
>> suggestions before I go in search of a different mic? Also, any
>> recommendations for a boom mount microphone that would be a better choice
>> for the K3S than this PR-781?
>>
> ______________________________________________________________
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>

Nr4c

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

What voltage does the K3S display while transmitting SSB?

Sent from my iPhone
...nr4c. bill

> On Mar 26, 2017, at 12:31 PM, Jim Kutsch <[hidden email]> wrote:
>
> I am a new K3S owner and very pleased. However, on SSB, I am getting reports
> that my audio is distorted sounding like RF is getting into the microphone.
> I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
> had some RF microphone issues earlier using the PR-781 with a KX3 but a
> better shielded mic cable and a common mode choke resolved it. Any
> suggestions before I go in search of a different mic? Also, any
> recommendations for a boom mount microphone that would be a better choice
> for the K3S than this PR-781?
>
>
>
> Thanks and 73, Jim, KY2D
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
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Jim Brown-10

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

Hi Jim,

RF feedback is most often caused by improper termination of a cable
shield. The only good termination of a cable shield is to the shielding
enclosure (that is, the chassis). I know nothing about Heil mics, so
can't offer advice about their adapter. I would take this issue up with
Heil.

But don't assume that RF is the only possibility. The mic gain and/or
the compression may be turned up too high, both of which can make you
sound pretty awful. And the adapter may be mis-wired -- every brand of
JA radios uses a different pin-out for their mic connectors. Elecraft
uses a pinout that's close to one of them (or may be the same). So
connector wired for one radio is usually not right for another. Some
people complain about "different standards," but this is an example of
there being NO standard, and each manufacturer throwing his own darts at
the board.

If it is a wiring issue, all you need to fix your problem is a few hand
tools and a soldering iron to open up the connectors and rewire them
according to the manuals for the respective components (the mic and the
radio).

The Yamaha CM500 is widely used by K3 owners. I've used one since a
local ham introduced our contesting club to it seven or eight years ago.
Both mic and headphones sound very good and it's quite comfortable. It
plugs straight into the jacks on the rear panel. It's an electret, so
you'll need to turn on bias.

73, Jim K9YC

73, Jim K9YC

On Sun,3/26/2017 9:31 AM, Jim Kutsch wrote:

> I am a new K3S owner and very pleased. However, on SSB, I am getting reports
> that my audio is distorted sounding like RF is getting into the microphone.
> I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
> had some RF microphone issues earlier using the PR-781 with a KX3 but a
> better shielded mic cable and a common mode choke resolved it. Any
> suggestions before I go in search of a different mic? Also, any
> recommendations for a boom mount microphone that would be a better choice
> for the K3S than this PR-781?
>
>
>
> Thanks and 73, Jim, KY2D
>
>
>
>
>
> ______________________________________________________________
> 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]
>

Jim Brown-10

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

On Sun,3/26/2017 9:31 AM, Jim Kutsch wrote:
> I am getting reports
> that my audio is distorted sounding like RF is getting into the microphone.

In writing my previous response, I forgot to mention this mechanism,
which can cause exactly what you are experiencing, and which has nothing
to do with RFI. This is only an issue when audio is being fed to the rig
via some audio accessory that runs on DC from the some power supply as
the rig.

http://k9yc.com/PowerSupplyBondingAndAudioDistortion.pdf

73, Jim K9YC

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Joe Subich, W4TV-4

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

Heil's quality control *sucks*. Their cables are notorious for
reversing mic return and chassis ground (shield/PTT return) and/or
connecting the mic return to the shell of the Foster plug instead
of the mic return pin.

Use an ohm meter and make sure that pin 1 of the XLR (shield/shell)
is connected to the *shell* of the Foster plug and pin 3 of the XLR
(mic return) is connected *only* to pin 7 of the Foster plug.

Connecting pin 7 of the Foster plug to the shell (particularly at
the XLR end of the cable) is a sure fire way to make any RFI problem
in your shack/installation exponentially worse.

73,

... Joe, W4TV

On 3/26/2017 12:31 PM, Jim Kutsch wrote:

Alan. G4GNX

Re: RF in Microphone

In reply to this post by Jim Brown-10

Jim.

What Mic Gain and Compression settings do you use with the CM500 headset?

A friend said that he uses MIC=40 and CMP=20, but Howard at Elecraft thinks
that's far too high.
I found that I can get the correct ALC response using Mic=11 and CMP=20.

73,

Alan. G4GNX

-----Original Message-----
From: Jim Brown
Sent: Sunday, March 26, 2017 6:47 PM
To: Reflector Elecraft
Subject: Re: [Elecraft] RF in Microphone

...........................The Yamaha CM500 is widely used by K3 owners.
I've used one since a
local ham introduced our contesting club to it seven or eight years ago.
Both mic and headphones sound very good and it's quite comfortable. It
plugs straight into the jacks on the rear panel. It's an electret, so
you'll need to turn on bias.

73, Jim K9YC

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Bill Frantz

Re: RF in Microphone

I use MIC = 8 or 9 and CMP=20. I found in the CQ WPX SSB contest
this weekend that raising the CMP to 25 increased the number of
times I was able to get through in the pileups.

73 Bill AE6JV

On 3/26/17 at 12:08 PM, [hidden email] (Alan. G4GNX) wrote:

>What Mic Gain and Compression settings do you use with the CM500 headset?
>
>A friend said that he uses MIC=40 and CMP=20, but Howard at Elecraft thinks that's far too high.
>I found that I can get the correct ALC response using Mic=11 and CMP=20.
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Alan. G4GNX

Re: RF in Microphone

Thanks Bill.

That tends to suggest that my setting of 11 is not too far off.

73,

Alan. G4GNX

-----Original Message-----
From: Bill Frantz
Sent: Sunday, March 26, 2017 8:32 PM
To: Alan. G4GNX
Cc: [hidden email]
Subject: Re: [Elecraft] RF in Microphone

I use MIC = 8 or 9 and CMP=20. I found in the CQ WPX SSB contest
this weekend that raising the CMP to 25 increased the number of
times I was able to get through in the pileups.

73 Bill AE6JV

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Jim Kutsch, KY2D-2

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

First, thanks to all who answered personally and on the list reflector. To
provide more info as several have requested, here's the setup:

The K3S is connected to a KPA500 then to a KAT500 then 25 feet of coax out
to the back porch. There, the coax ends in a common mode choke, which in
turn is connected by an 18 inch coax to a DX Engineering 4:1 BALUN. That
feeds a Cobra UltraLite Senior via its 81 feet of 450 Ohm ladder line. The
mic distortion happens with and without the KPA500 but reports say it's
worse at 500 Watts.

The power supply is an Astron RS35 providing 13.8V idle and 13.5V CW key
down at 100 Watts.

The mic gain is set to 45 and compression to 10. Those seemed to give the
correct indication in the ALC meter but the distortion still occurs with 0
compression. I cannot read the ALC indicator myself due to no vision so had
another local ham assist with that part of the K3S setup.

Jim

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Jim
Kutsch
Sent: Sunday, March 26, 2017 12:31 PM
To: [hidden email]
Subject: [Elecraft] RF in Microphone

I am a new K3S owner and very pleased. However, on SSB, I am getting reports
that my audio is distorted sounding like RF is getting into the microphone.
I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
had some RF microphone issues earlier using the PR-781 with a KX3 but a
better shielded mic cable and a common mode choke resolved it. Any
suggestions before I go in search of a different mic? Also, any
recommendations for a boom mount microphone that would be a better choice
for the K3S than this PR-781?

Thanks and 73, Jim, KY2D

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Mike VE3YF

Re: RF in Microphone

Jim:

Personally I think that the mic gain is up way to far. I use a PR-40 so
the setting should be roughly the same. My mic gain is 12 and cmp is 15.
I also have the mic setting to the hi instead of the recommended low
setting and also have the TXG VCE set to 2.0. Give or take, my setting
should be pretty good for you, of course depending on your voice
characteristics. I think is is better to be a bit on the low side for
the settings then to be on the high side. Give it a whirl and see how
they work out for you.
--

*73 De Mike*
*VE3YF

_/http://www.ve3yf.com/_*

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Don Wilhelm

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

Jim,

Your mic gain is on the high side. If you have the mic gain range set
to "Low", try changing it to "High" and lowering the gain to the 10 to
15 range.
Turn compression to zero while the mic gain is adjusted for 5 to 7 bars
(7 on peaks) on the ALC meter. After making that setting increase the
compression to whatever you desire - most like to run compression in the
10 to 15 range.

See if you can borrow someone who can see the ALC meter while you talk.
Set the K3 to TX TEST so you don't send RF while you make those adjustments.

73,
Don W3FPR

On 3/26/2017 5:38 PM, Jim Kutsch wrote:

> The mic gain is set to 45 and compression to 10. Those seemed to give the
> correct indication in the ALC meter but the distortion still occurs with 0
> compression. I cannot read the ALC indicator myself due to no vision so had
> another local ham assist with that part of the K3S setup.
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Jim Kutsch, KY2D-2

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

Some progress but some new questions. When transmitting at 12 Watts without
the KPA3 engaged, the transmit audio is completely fine. But, once I go to
13 Watts and hear the KPA3 relay engage, the audio distortion is back. I'm
beginning to think I have a CONF setting incorrect or the KPA3 is bad. Even
with 12 W driving the KPA500, no audio distortion.
The K3S has the KPA3 module but does not have the KAT3 since I'm using the
KAP500.

I have CONF:KPA3 set to PA NOR. Am I missing another menu setting somewhere?

Jim

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Don Wilhelm

Re: RF in Microphone

Jim,

With that new information, I suggest you email K3support to see if they
can add anything and suggest a fix. Let them know the serial number of
your K3S as well as the firmware level.

73,
Don W3FPR

On 3/26/2017 7:02 PM, Jim Kutsch wrote:
> Some progress but some new questions. When transmitting at 12 Watts without
> the KPA3 engaged, the transmit audio is completely fine. But, once I go to
> 13 Watts and hear the KPA3 relay engage, the audio distortion is back. I'm
> beginning to think I have a CONF setting incorrect or the KPA3 is bad. Even
> with 12 W driving the KPA500, no audio distortion.
> The K3S has the KPA3 module but does not have the KAT3 since I'm using the
> KAP500.
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Jim Brown-10

Re: RF in Microphone

In reply to this post by Alan. G4GNX

That depends on your voice and how you place the mic. It also depends on
the Mic Gain setting in the menu. My rigs are set for Low mic gain.

Never set these parameters by the numbers on the knob readouts. Set them
watching the display of ALC and CMP. These settings should ALWAYS be set
in this order:

1) Set TXEQ as desired. I recommend maximum cut of the three lowest
bands, 6 dB cut of the fourth band, 3-6 dB boost of the two highest
bands. Tweak the 4th band and the higher bands based on reports from
good listeners, who should be listening with their IF set wide.

2) With compression OFF (set to zero), set the mic gain for ALC of 5-7 bars.

3) Set CMP so that the display shows about 10 dB of gain reduction on
voice peaks.

73, Jim K9YC

On Sun,3/26/2017 12:08 PM, Alan. G4GNX wrote:
> What Mic Gain and Compression settings do you use with the CM500 headset?
>
> A friend said that he uses MIC=40 and CMP=20, but Howard at Elecraft
> thinks that's far too high.
> I found that I can get the correct ALC response using Mic=11 and CMP=20.
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Kenneth Christiansen

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

Hi Jim

The answer to your problem is you have a bad FET in the final of your K3S. I had the same problem and my K3S is at Elecraft right now being repaired. The distortion above the 12 watt level is the clue.

I also have the KPA500 and the KAT500 and I had a problem with my antenna that it would sometimes short out at 500 watts and the KPA500 was not set up for the KPA500. I had figured since I bought both units together they would just work. I had even read the missing instructions but they did not make sense to me so I did not do them. Now that I found out what was involved they make sense but I think that part of the instructions should be more clear or a control in the MENU should allow the settings to be compatible with the KAP500.

To make this long story short if the KAT500 is not set up to be comparable with the KPA500 than if there is a high SWR it does not shut down the KPA500 and when the KPA500 does shut down all those high SWR voltages get back to the K3S and blow one of the FETs. There are two FETs so the other one tries to make up the power and of course the bad one causes distortion similar to a diode being placed across the final.

I hope this information helps and for what it is worth I managed to destroy my finals twice before I found out what was wrong.

Good luck and 73

Ken
W0CZ
w0cz at i29 dot net

Sent from my iPad

> On Mar 26, 2017, at 4:38 PM, Jim Kutsch <[hidden email]> wrote:
>
> First, thanks to all who answered personally and on the list reflector. To
> provide more info as several have requested, here's the setup:
>
> The K3S is connected to a KPA500 then to a KAT500 then 25 feet of coax out
> to the back porch. There, the coax ends in a common mode choke, which in
> turn is connected by an 18 inch coax to a DX Engineering 4:1 BALUN. That
> feeds a Cobra UltraLite Senior via its 81 feet of 450 Ohm ladder line. The
> mic distortion happens with and without the KPA500 but reports say it's
> worse at 500 Watts.
>
> The power supply is an Astron RS35 providing 13.8V idle and 13.5V CW key
> down at 100 Watts.
>
> The mic gain is set to 45 and compression to 10. Those seemed to give the
> correct indication in the ALC meter but the distortion still occurs with 0
> compression. I cannot read the ALC indicator myself due to no vision so had
> another local ham assist with that part of the K3S setup.
>
> Jim
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Jim
> Kutsch
> Sent: Sunday, March 26, 2017 12:31 PM
> To: [hidden email]
> Subject: [Elecraft] RF in Microphone
>
> I am a new K3S owner and very pleased. However, on SSB, I am getting reports
> that my audio is distorted sounding like RF is getting into the microphone.
> I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter cable. I
> had some RF microphone issues earlier using the PR-781 with a KX3 but a
> better shielded mic cable and a common mode choke resolved it. Any
> suggestions before I go in search of a different mic? Also, any
> recommendations for a boom mount microphone that would be a better choice
> for the K3S than this PR-781?
>
>
>
> Thanks and 73, Jim, KY2D
>
>
>
>
>
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> delivered to [hidden email]
>
> ______________________________________________________________
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>

Bill K9YEQ

Re: RF in Microphone

I think there is more to it than this. The return path to the K3s via a reflected power from the KPA500 is not acceptable and should be protected. I load my KPA500 into a matched circuit. Yes, I am sure there could be instantaneous issues, but my antennas are pretuned before I use the KPA500. Is there an opportunity for error. Yes. I operated a THP 2.5KFX at 1.5KW and saw the same antennas and never had an issue to the K3. I know the engineers are working on the issue(s). I suspect a change is en route.

73,
Bill
K9YEQ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Kenneth Christiansen
Sent: Sunday, March 26, 2017 7:23 PM
To: Jim Kutsch <[hidden email]>
Cc: [hidden email]
Subject: Re: [Elecraft] RF in Microphone

Hi Jim

The answer to your problem is you have a bad FET in the final of your K3S. I had the same problem and my K3S is at Elecraft right now being repaired. The distortion above the 12 watt level is the clue.

I also have the KPA500 and the KAT500 and I had a problem with my antenna that it would sometimes short out at 500 watts and the KPA500 was not set up for the KPA500. I had figured since I bought both units together they would just work. I had even read the missing instructions but they did not make sense to me so I did not do them. Now that I found out what was involved they make sense but I think that part of the instructions should be more clear or a control in the MENU should allow the settings to be compatible with the KAP500.

To make this long story short if the KAT500 is not set up to be comparable with the KPA500 than if there is a high SWR it does not shut down the KPA500 and when the KPA500 does shut down all those high SWR voltages get back to the K3S and blow one of the FETs. There are two FETs so the other one tries to make up the power and of course the bad one causes distortion similar to a diode being placed across the final.

I hope this information helps and for what it is worth I managed to destroy my finals twice before I found out what was wrong.

Good luck and 73

Ken
W0CZ
w0cz at i29 dot net

Sent from my iPad

> On Mar 26, 2017, at 4:38 PM, Jim Kutsch <[hidden email]> wrote:
>
> First, thanks to all who answered personally and on the list
> reflector. To provide more info as several have requested, here's the setup:
>
> The K3S is connected to a KPA500 then to a KAT500 then 25 feet of coax
> out to the back porch. There, the coax ends in a common mode choke,
> which in turn is connected by an 18 inch coax to a DX Engineering 4:1
> BALUN. That feeds a Cobra UltraLite Senior via its 81 feet of 450 Ohm
> ladder line. The mic distortion happens with and without the KPA500
> but reports say it's worse at 500 Watts.
>
> The power supply is an Astron RS35 providing 13.8V idle and 13.5V CW
> key down at 100 Watts.
>
> The mic gain is set to 45 and compression to 10. Those seemed to give
> the correct indication in the ALC meter but the distortion still
> occurs with 0 compression. I cannot read the ALC indicator myself due
> to no vision so had another local ham assist with that part of the K3S setup.
>
> Jim
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of
> Jim Kutsch
> Sent: Sunday, March 26, 2017 12:31 PM
> To: [hidden email]
> Subject: [Elecraft] RF in Microphone
>
> I am a new K3S owner and very pleased. However, on SSB, I am getting
> reports that my audio is distorted sounding like RF is getting into the microphone.
> I'm using a Heil PR-781 with the XLR3 to 8-pin microphone adapter
> cable. I had some RF microphone issues earlier using the PR-781 with a
> KX3 but a better shielded mic cable and a common mode choke resolved
> it. Any suggestions before I go in search of a different mic? Also,
> any recommendations for a boom mount microphone that would be a better
> choice for the K3S than this PR-781?
>
>
>
> Thanks and 73, Jim, KY2D
>
>
>
>
>
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Dave Hachadorian-2

Re: RF in Microphone

In reply to this post by Jim Kutsch, KY2D-2

What happens if you transmit 100 watts into a dummy load?

Dave Hachadorian, K6LL
Yuma, Arizona

-----Original Message-----
From: Jim Kutsch
Sent: Sunday, March 26, 2017 4:02 PM
To: [hidden email]
Subject: Re: [Elecraft] RF in Microphone

Some progress but some new questions. When transmitting at 12
Watts without
the KPA3 engaged, the transmit audio is completely fine. But,
once I go to
13 Watts and hear the KPA3 relay engage, the audio distortion is
back. I'm
beginning to think I have a CONF setting incorrect or the KPA3 is
bad. Even
with 12 W driving the KPA500, no audio distortion.
The K3S has the KPA3 module but does not have the KAT3 since I'm
using the
KAP500.

I have CONF:KPA3 set to PA NOR. Am I missing another menu setting
somewhere?

Jim

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