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[K3] - Hum on SSB Transmissions

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Joseph Rogers

[K3] - Hum on SSB Transmissions

I normally operate CW but the other day and have not been SSB for a few weeks to a month. Yesterday, I was getting ready to operate SSB and I noted a hum through the monitor when I key the transmitter. By way of background, K3 is 2012 vintage and I assembled the kit. No problems with until this one. I have found several similar threads mentioning a hum on SSB transmit but of the mentioned solutions worked to solve my problem.

I have Heil Pro set IC and Heil Gold Elite. The problem seems much more pronounced with Proset IC.

Whether it is connected to front panel (FP.H or RP.H Bias on) makes no difference. If I used PTT or VOX it is there. Set Mic Gain at anything above zero it starts. With higher mic gain and higher compression it is worse. I have made some PSK contacts using the LIN IN input and seems to work OK.

It seemed like low frequency noise so I set the TX filters for 50 and 100 Hz from 0 to -16. No change.

Changed TX Gate from 0 to 10. No change.

Disconnected everything from the K3 - RS232 cable, the antennas, keys, and paddle. All except power supply and the Mic. No change.

Mic+Lin ON or OFF no change.

Curiously, if I put my hand on the rig, it seems to reduce the volume of the hum.

Recorded some audio with Proset on my PC and it seems clean - no noise detectable.

I wonder if any of you guys - all of you probably more technically savvy than I - can come up with any ideas to solve this problem.

Thanks in advance for any help you can give me.

73,
Joe
AJ1Y
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73's
Joe
AJ1Y

Don Wilhelm

Re: [K3] - Hum on SSB Transmissions

Joe,

Do you hear that hum when you operate into a dummy load? If not, then
check the common mode choke on the antenna, you are likely getting
RF-In-the-Shack from the antenna - the fact that it diminishes when you
put your hand on the K3 amplifies that this may be the problem. Forget
about grounding the radio for this problem, solve it at the antenna
feedpoint with a good common mode choke on the feedline.

Other possibilities are power supply ripple (run it on battery to check)
or an open microphone ground lead (try other microphones).
Make sure the rear panel jacks are fully plugged (give them an extra push).

73,
Don W3FPR

On 12/2/2018 4:17 PM, Joe Rogers wrote:
> I normally operate CW but the other day and have not been SSB for a few weeks to a month. Yesterday, I was getting ready to operate SSB and I noted a hum through the monitor when I key the transmitter. By way of background, K3 is 2012 vintage and I assembled the kit. No problems with until this one. I have found several similar threads mentioning a hum on SSB transmit but of the mentioned solutions worked to solve my problem.
>
> I have Heil Pro set IC and Heil Gold Elite. The problem seems much more pronounced with Proset IC.
>
> Whether it is connected to front panel (FP.H or RP.H Bias on) makes no difference. If I used PTT or VOX it is there. Set Mic Gain at anything above zero it starts. With higher mic gain and higher compression it is worse. I have made some PSK contacts using the LIN IN input and seems to work OK.
>
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Dale Boresz

Re: [K3] - Hum on SSB Transmissions

In reply to this post by Joseph Rogers

Joe,

You might check to see if the amplitude of the hum changes as you alter the
position of the microphone. If so, the magnetic field of a transformer from
another piece of equipment in the shack (such as a linear power supply) may
be coupling into your microphone.

73,
Dale - WA8SRA

On Sun, Dec 2, 2018 at 4:19 PM Joe Rogers <[hidden email]> wrote:

> I normally operate CW but the other day and have not been SSB for a few
> weeks to a month. Yesterday, I was getting ready to operate SSB and I
> noted a hum through the monitor when I key the transmitter. By way of
> background, K3 is 2012 vintage and I assembled the kit. No problems with
> until this one. I have found several similar threads mentioning a hum on
> SSB transmit but of the mentioned solutions worked to solve my problem.
>
> I have Heil Pro set IC and Heil Gold Elite. The problem seems much more
> pronounced with Proset IC.
>
> Whether it is connected to front panel (FP.H or RP.H Bias on) makes no
> difference. If I used PTT or VOX it is there. Set Mic Gain at anything
> above zero it starts. With higher mic gain and higher compression it is
> worse. I have made some PSK contacts using the LIN IN input and seems to
> work OK.
>
> It seemed like low frequency noise so I set the TX filters for 50 and 100
> Hz from 0 to -16. No change.
>
> Changed TX Gate from 0 to 10. No change.
>
> Disconnected everything from the K3 - RS232 cable, the antennas, keys, and
> paddle. All except power supply and the Mic. No change.
>
> Mic+Lin ON or OFF no change.
>
> Curiously, if I put my hand on the rig, it seems to reduce the volume of
> the hum.
>
> Recorded some audio with Proset on my PC and it seems clean - no noise
> detectable.
>
> I wonder if any of you guys - all of you probably more technically savvy
> than I - can come up with any ideas to solve this problem.
>
> Thanks in advance for any help you can give me.
>
> 73,
> Joe
> AJ1Y
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Message delivered to [hidden email]
>

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Joseph Rogers

Re: [K3] - Hum on SSB Transmissions

Hi Dale,

Checked that out. No effect on the position of the mike.

I have a feeling that it is a break in the shielding allowing the 60 Hz to get onto the audio.

Have visually checked the electret element – nothing obviously wrong. As this is a relatively new Proset have contacted Heil.

Thanks for the suggestion.

73
Joe
AJ1Y

From: Dale Boresz <[hidden email]>
Sent: Monday, December 3, 2018 20:33
To: [hidden email]
Cc: Elecraft <[hidden email]>
Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions

Joe,

You might check to see if the amplitude of the hum changes as you alter the position of the microphone. If so, the magnetic field of a transformer from another piece of equipment in the shack (such as a linear power supply) may be coupling into your microphone.

73,
Dale - WA8SRA

On Sun, Dec 2, 2018 at 4:19 PM Joe Rogers <[hidden email]<mailto:[hidden email]>> wrote:
I normally operate CW but the other day and have not been SSB for a few weeks to a month. Yesterday, I was getting ready to operate SSB and I noted a hum through the monitor when I key the transmitter. By way of background, K3 is 2012 vintage and I assembled the kit. No problems with until this one. I have found several similar threads mentioning a hum on SSB transmit but of the mentioned solutions worked to solve my problem.

I have Heil Pro set IC and Heil Gold Elite. The problem seems much more pronounced with Proset IC.

Whether it is connected to front panel (FP.H or RP.H Bias on) makes no difference. If I used PTT or VOX it is there. Set Mic Gain at anything above zero it starts. With higher mic gain and higher compression it is worse. I have made some PSK contacts using the LIN IN input and seems to work OK.

It seemed like low frequency noise so I set the TX filters for 50 and 100 Hz from 0 to -16. No change.

Changed TX Gate from 0 to 10. No change.

Disconnected everything from the K3 - RS232 cable, the antennas, keys, and paddle. All except power supply and the Mic. No change.

Mic+Lin ON or OFF no change.

Curiously, if I put my hand on the rig, it seems to reduce the volume of the hum.

Recorded some audio with Proset on my PC and it seems clean - no noise detectable.

I wonder if any of you guys - all of you probably more technically savvy than I - can come up with any ideas to solve this problem.

Thanks in advance for any help you can give me.

73,
Joe
AJ1Y
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73's
Joe
AJ1Y

Joseph Rogers

Re: [K3] - Hum on SSB Transmissions

In reply to this post by Don Wilhelm

Hi Don,

Thanks for the email suggestions.

I ran some on air checks of the Proset and the other mike I have - a Gold Elite. Gold Elite audio was fine. Proset was poor. Believe it is the open microphone ground lead problem that you mentioned.

Thanks,

73
Joe AJ1Y

-----Original Message-----
From: Don Wilhelm <[hidden email]>
Sent: Monday, December 3, 2018 19:44
To: Joe Rogers <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions

Joe,

Do you hear that hum when you operate into a dummy load? If not, then check the common mode choke on the antenna, you are likely getting RF-In-the-Shack from the antenna - the fact that it diminishes when you put your hand on the K3 amplifies that this may be the problem. Forget about grounding the radio for this problem, solve it at the antenna feedpoint with a good common mode choke on the feedline.

Other possibilities are power supply ripple (run it on battery to check) or an open microphone ground lead (try other microphones).
Make sure the rear panel jacks are fully plugged (give them an extra push).

73,
Don W3FPR

On 12/2/2018 4:17 PM, Joe Rogers wrote:
> I normally operate CW but the other day and have not been SSB for a few weeks to a month. Yesterday, I was getting ready to operate SSB and I noted a hum through the monitor when I key the transmitter. By way of background, K3 is 2012 vintage and I assembled the kit. No problems with until this one. I have found several similar threads mentioning a hum on SSB transmit but of the mentioned solutions worked to solve my problem.
>
> I have Heil Pro set IC and Heil Gold Elite. The problem seems much more pronounced with Proset IC.
>
> Whether it is connected to front panel (FP.H or RP.H Bias on) makes no difference. If I used PTT or VOX it is there. Set Mic Gain at anything above zero it starts. With higher mic gain and higher compression it is worse. I have made some PSK contacts using the LIN IN input and seems to work OK.
>
______________________________________________________________
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]

73's
Joe
AJ1Y

Don Wilhelm

Re: [K3] - Hum on SSB Transmissions

Joe,

If you are using the Front Panel adapter for the ProSet-Ic, try plugging
the microphone into the MIC jack in the back of the K3 and changing the
MIC SEL menu to the rear panel.
If the hum is not present, then you have a bad adapter instead of a bad mic.

73,
Don W3FPR

On 12/4/2018 10:32 AM, Joe Rogers wrote:

> Hi Don,
>
> Thanks for the email suggestions.
>
> I ran some on air checks of the Proset and the other mike I have - a Gold Elite. Gold Elite audio was fine. Proset was poor. Believe it is the open microphone ground lead problem that you mentioned.
>
> Thanks,
>
> 73
> Joe AJ1Y
>
>
> -----Original Message-----
> From: Don Wilhelm <[hidden email]>
> Sent: Monday, December 3, 2018 19:44
> To: Joe Rogers <[hidden email]>; [hidden email]
> Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions
>
> Joe,
>
> Do you hear that hum when you operate into a dummy load? If not, then check the common mode choke on the antenna, you are likely getting RF-In-the-Shack from the antenna - the fact that it diminishes when you put your hand on the K3 amplifies that this may be the problem. Forget about grounding the radio for this problem, solve it at the antenna feedpoint with a good common mode choke on the feedline.
>
> Other possibilities are power supply ripple (run it on battery to check) or an open microphone ground lead (try other microphones).
> Make sure the rear panel jacks are fully plugged (give them an extra push).
>
> 73,
> Don W3FPR
>
> On 12/2/2018 4:17 PM, Joe Rogers wrote:
>> I normally operate CW but the other day and have not been SSB for a few weeks to a month. Yesterday, I was getting ready to operate SSB and I noted a hum through the monitor when I key the transmitter. By way of background, K3 is 2012 vintage and I assembled the kit. No problems with until this one. I have found several similar threads mentioning a hum on SSB transmit but of the mentioned solutions worked to solve my problem.
>>
>> I have Heil Pro set IC and Heil Gold Elite. The problem seems much more pronounced with Proset IC.
>>
>> Whether it is connected to front panel (FP.H or RP.H Bias on) makes no difference. If I used PTT or VOX it is there. Set Mic Gain at anything above zero it starts. With higher mic gain and higher compression it is worse. I have made some PSK contacts using the LIN IN input and seems to work OK.
>>

Joseph Rogers

Re: [K3] - Hum on SSB Transmissions

Hi Don,

You hit upon exactly what I did!! When I last did on air checks, I had the Proset in the rear panel jack and had same hum as in front panel - which, as you pointed out, would indicate that the adapter was not the problem and the issue is in the Proset itself.

I am pretty much convinced it is in the Proset IC now. I just cannot understand why after only about a year, I have this failure. My prior Proset was 6 years old and no problem. Anyway, I am talking to Heil and hope to get the whole issue sorted out.

73
Joe AJ1Y

-----Original Message-----
From: Don Wilhelm <[hidden email]>
Sent: Tuesday, December 4, 2018 10:48
To: Joe Rogers <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions

Joe,

If you are using the Front Panel adapter for the ProSet-Ic, try plugging the microphone into the MIC jack in the back of the K3 and changing the MIC SEL menu to the rear panel.
If the hum is not present, then you have a bad adapter instead of a bad mic.

73,
Don W3FPR

On 12/4/2018 10:32 AM, Joe Rogers wrote:

73's
Joe
AJ1Y

Alan Bloom

Re: [K3] - Hum on SSB Transmissions

Alan Bloom

Re: [K3] - Hum on SSB Transmissions

In reply to this post by Joseph Rogers

Joseph Rogers

Re: [K3] - Hum on SSB Transmissions

In reply to this post by Joseph Rogers

Hi Alan,

Thanks.

I saw you try to hit the reflector twice but nothing came through. Thanks for that suggestion but I think I found the problem. Looks like 60 Hz leaking into the mic from an open ground somewhere in the mic line to the headset.

You raise a good point that I had not considered. I will keep it in mind in case I run into a problem in the future.

73
Joe
AJ1Y

From: Alan <[hidden email]>
Sent: Tuesday, December 4, 2018 19:18
To: Joe Rogers <[hidden email]>
Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions

Hi Joe,

I twice tried to reply on the reflector, but both times the message posted with no text. No idea what's going on.

Anyway, you might check if the problem could be hum getting into the mic mechanically.

At the community radio station I volunteer for we had hum on the desk mics in the main studio, but only when they were on the same table as the studio computer. I finally figured out it was vibration from the fan in the computer transmitted via the table to the mics.

As an experiment you might try lifting the mic off the table. If that makes the hum go away, then it's likely mechanical vibration.

The solution could be a shock-mounted mic or perhaps a boom mic mounted to the wall.

73,

Alan N1AL

On 12/4/18 8:03 AM, Joe Rogers wrote:

Hi Don,

You hit upon exactly what I did!! When I last did on air checks, I had the Proset in the rear panel jack and had same hum as in front panel - which, as you pointed out, would indicate that the adapter was not the problem and the issue is in the Proset itself.

I am pretty much convinced it is in the Proset IC now. I just cannot understand why after only about a year, I have this failure. My prior Proset was 6 years old and no problem. Anyway, I am talking to Heil and hope to get the whole issue sorted out.

73

Joe AJ1Y

-----Original Message-----

From: Don Wilhelm <[hidden email]><mailto:[hidden email]>

Sent: Tuesday, December 4, 2018 10:48

To: Joe Rogers <[hidden email]><mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>

Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions

Joe,

If you are using the Front Panel adapter for the ProSet-Ic, try plugging the microphone into the MIC jack in the back of the K3 and changing the MIC SEL menu to the rear panel.

If the hum is not present, then you have a bad adapter instead of a bad mic.

73,

Don W3FPR

On 12/4/2018 10:32 AM, Joe Rogers wrote:

Hi Don,

Thanks for the email suggestions.

I ran some on air checks of the Proset and the other mike I have - a Gold Elite. Gold Elite audio was fine. Proset was poor. Believe it is the open microphone ground lead problem that you mentioned.

Thanks,

73

Joe AJ1Y

-----Original Message-----

From: Don Wilhelm <[hidden email]><mailto:[hidden email]>

Sent: Monday, December 3, 2018 19:44

To: Joe Rogers <[hidden email]><mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>

Subject: Re: [Elecraft] [K3] - Hum on SSB Transmissions

Joe,

Do you hear that hum when you operate into a dummy load? If not, then check the common mode choke on the antenna, you are likely getting RF-In-the-Shack from the antenna - the fact that it diminishes when you put your hand on the K3 amplifies that this may be the problem. Forget about grounding the radio for this problem, solve it at the antenna feedpoint with a good common mode choke on the feedline.

Other possibilities are power supply ripple (run it on battery to check) or an open microphone ground lead (try other microphones).

Make sure the rear panel jacks are fully plugged (give them an extra push).

73,

Don W3FPR

On 12/2/2018 4:17 PM, Joe Rogers wrote:

I normally operate CW but the other day and have not been SSB for a few weeks to a month. Yesterday, I was getting ready to operate SSB and I noted a hum through the monitor when I key the transmitter. By way of background, K3 is 2012 vintage and I assembled the kit. No problems with until this one. I have found several similar threads mentioning a hum on SSB transmit but of the mentioned solutions worked to solve my problem.

I have Heil Pro set IC and Heil Gold Elite. The problem seems much more pronounced with Proset IC.

Whether it is connected to front panel (FP.H or RP.H Bias on) makes no difference. If I used PTT or VOX it is there. Set Mic Gain at anything above zero it starts. With higher mic gain and higher compression it is worse. I have made some PSK contacts using the LIN IN input and seems to work OK.

______________________________________________________________

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73's
Joe
AJ1Y