Elecraft

K4 observation

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John Harper

K4 observation

https://www.youtube.com/watch?v=u1XRaNpgQDI

John AE5X
https://ae5x.blogspot.com

>Noticed that when the antenna are disconnected, and the K4 turned off, I hear a local TV station in the headphones… Never happened on the K3.
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wayne burdick

Re: K4 observation

Administrator

John,

If the K4 is *off*, then there's no active circuitry involved. However, the headphone plug-insertion detect circuit may involve an IC downstream that could include a schottky diode junction -- a potential way a very strong signal could be rectified right at the radio end of the cable. We're looking at that.

If the cable is not very well shielded, and the TV station is *very strong*, I can imagine modern physics just barely covering this situation. It would help if the headphone cable was about the length of an end-fed dipole at the station's frequency.

As for the K4 chassis itself: It's very well sealed (far better than the K3/K3S).

Wayne
N6KR

> On Jun 18, 2021, at 3:36 PM, John Harper <[hidden email]> wrote:
>
> https://www.youtube.com/watch?v=u1XRaNpgQDI
>
> John AE5X
> https://ae5x.blogspot.com
>
>> Noticed that when the antenna are disconnected, and the K4 turned off, I hear a local TV station in the headphones… Never happened on the K3.
> ______________________________________________________________

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Paul Van Dyke

Re: K4 observation

John

Would you put that under "Worked All Molars?"

Paul KB9AVO

On Fri, Jun 18, 2021, 10:35 PM Wayne Burdick <[hidden email]> wrote:

> John,
>
> If the K4 is *off*, then there's no active circuitry involved. However,
> the headphone plug-insertion detect circuit may involve an IC downstream
> that could include a schottky diode junction -- a potential way a very
> strong signal could be rectified right at the radio end of the cable. We're
> looking at that.
>
> If the cable is not very well shielded, and the TV station is *very
> strong*, I can imagine modern physics just barely covering this situation.
> It would help if the headphone cable was about the length of an end-fed
> dipole at the station's frequency.
>
> As for the K4 chassis itself: It's very well sealed (far better than the
> K3/K3S).
>
> Wayne
> N6KR
>
>
>
> > On Jun 18, 2021, at 3:36 PM, John Harper <[hidden email]> wrote:
> >
> > https://www.youtube.com/watch?v=u1XRaNpgQDI
> >
> > John AE5X
> > https://ae5x.blogspot.com
> >
> >> Noticed that when the antenna are disconnected, and the K4 turned off,
> I hear a local TV station in the headphones… Never happened on the K3.
> > ______________________________________________________________
>
>
> ______________________________________________________________
> 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]

W2xj

Re: K4 observation

In reply to this post by wayne burdick

Wayne

I seriously doubt this is an RF issue. TV is all digital and has no discrete audio carrier. TV RF interference would sound like white noise. This sounds more like an audio ground loop of some sort.

> On June 18, 2021 10:33 PM Wayne Burdick <[hidden email]> wrote:
>
>
> John,
>
> If the K4 is *off*, then there's no active circuitry involved. However, the headphone plug-insertion detect circuit may involve an IC downstream that could include a schottky diode junction -- a potential way a very strong signal could be rectified right at the radio end of the cable. We're looking at that.
>
> If the cable is not very well shielded, and the TV station is *very strong*, I can imagine modern physics just barely covering this situation. It would help if the headphone cable was about the length of an end-fed dipole at the station's frequency.
>
> As for the K4 chassis itself: It's very well sealed (far better than the K3/K3S).
>
> Wayne
> N6KR
>
>
>
> > On Jun 18, 2021, at 3:36 PM, John Harper <[hidden email]> wrote:
> >
> > https://www.youtube.com/watch?v=u1XRaNpgQDI
> >
> > John AE5X
> > https://ae5x.blogspot.com
> >
> >> Noticed that when the antenna are disconnected, and the K4 turned off, I hear a local TV station in the headphones… Never happened on the K3.
> > ______________________________________________________________
>
>
> ______________________________________________________________
> 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

Re: K4 observation

Actually, it could be a radio station. I haven’t listened long enough to ascertain…

Frankly, I don’t care! The bigger problem is the rfi when I transmit.

Tom W4KX

Sent from my iPad

> On Jun 18, 2021, at 11:10 PM, w2xj <[hidden email]> wrote:
>
>
> Wayne
>
> I seriously doubt this is an RF issue. TV is all digital and has no discrete audio carrier. TV RF interference would sound like white noise. This sounds more like an audio ground loop of some sort.
>
>
>
>
>> On June 18, 2021 10:33 PM Wayne Burdick <[hidden email]> wrote:
>>
>>
>> John,
>>
>> If the K4 is *off*, then there's no active circuitry involved. However, the headphone plug-insertion detect circuit may involve an IC downstream that could include a schottky diode junction -- a potential way a very strong signal could be rectified right at the radio end of the cable. We're looking at that.
>>
>> If the cable is not very well shielded, and the TV station is *very strong*, I can imagine modern physics just barely covering this situation. It would help if the headphone cable was about the length of an end-fed dipole at the station's frequency.
>>
>> As for the K4 chassis itself: It's very well sealed (far better than the K3/K3S).
>>
>> Wayne
>> N6KR
>>
>>
>>
>>>> On Jun 18, 2021, at 3:36 PM, John Harper <[hidden email]> wrote:
>>>
>>> https://www.youtube.com/watch?v=u1XRaNpgQDI
>>>
>>> John AE5X
>>> https://ae5x.blogspot.com
>>>
>>>> Noticed that when the antenna are disconnected, and the K4 turned off, I hear a local TV station in the headphones… Never happened on the K3.
>>> ______________________________________________________________
>>
>>
>> ______________________________________________________________
>> 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
> 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]

wayne burdick

Re: K4 observation

Administrator

> On Jun 19, 2021, at 3:17 AM, Tom Doligalski <[hidden email]> wrote:
>
> Actually, it could be a radio station. I haven’t listened long enough to ascertain…
>
> Frankly, I don’t care! The bigger problem is the rfi when I transmit.

Which *will* be fixed.

Wayne

>
> Tom W4KX
>
> Sent from my iPad
>
>> On Jun 18, 2021, at 11:10 PM, w2xj <[hidden email]> wrote:
>>
>>
>> Wayne
>>
>> I seriously doubt this is an RF issue. TV is all digital and has no discrete audio carrier. TV RF interference would sound like white noise. This sounds more like an audio ground loop of some sort.
>>
>>
>>
>>
>>> On June 18, 2021 10:33 PM Wayne Burdick <[hidden email]> wrote:
>>>
>>>
>>> John,
>>>
>>> If the K4 is *off*, then there's no active circuitry involved. However, the headphone plug-insertion detect circuit may involve an IC downstream that could include a schottky diode junction -- a potential way a very strong signal could be rectified right at the radio end of the cable. We're looking at that.
>>>
>>> If the cable is not very well shielded, and the TV station is *very strong*, I can imagine modern physics just barely covering this situation. It would help if the headphone cable was about the length of an end-fed dipole at the station's frequency.
>>>
>>> As for the K4 chassis itself: It's very well sealed (far better than the K3/K3S).
>>>
>>> Wayne
>>> N6KR
>>>
>>>
>>>
>>>>> On Jun 18, 2021, at 3:36 PM, John Harper <[hidden email]> wrote:
>>>>
>>>> https://www.youtube.com/watch?v=u1XRaNpgQDI
>>>>
>>>> John AE5X
>>>> https://ae5x.blogspot.com
>>>>
>>>>> Noticed that when the antenna are disconnected, and the K4 turned off, I hear a local TV station in the headphones… Never happened on the K3.
>>>> ______________________________________________________________
>>>
>>>
>>> ______________________________________________________________
>>> 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
>> 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]

wa6vab

Re: K4 observation

Did You Trying Transmitting in CW mode with the Mic disconnected ?
WA6VAB ray

From: Wayne Burdick
Sent: Saturday, June 19, 2021 11:41 AM
To: Tom Doligalski
Cc: Elecraft Reflector; John Harper
Subject: Re: [Elecraft] K4 observation

> On Jun 19, 2021, at 3:17 AM, Tom Doligalski <[hidden email]> wrote:
>
> Actually, it could be a radio station. I haven’t listened long enough to ascertain…
>
> Frankly, I don’t care! The bigger problem is the rfi when I transmit.

Which *will* be fixed.

Wayne

______________________________________________________________
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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Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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wayne burdick

Re: K4 observation

Administrator

I'm glad you beat me to this, Ray :)

Wayne

> On Jun 19, 2021, at 11:50 AM, Ray <[hidden email]> wrote:
>
> Did You Trying Transmitting in CW mode with the Mic disconnected ?
> WA6VAB ray
>
>
> From: Wayne Burdick
> Sent: Saturday, June 19, 2021 11:41 AM
> To: Tom Doligalski
> Cc: Elecraft Reflector; John Harper
> Subject: Re: [Elecraft] K4 observation
>
>
> > On Jun 19, 2021, at 3:17 AM, Tom Doligalski <[hidden email]> wrote:
> >
> > Actually, it could be a radio station. I haven’t listened long enough to ascertain…
> >
> > Frankly, I don’t care! The bigger problem is the rfi when I transmit.
>
> Which *will* be fixed.
>
> Wayne
>
> >
> > Tom W4KX
> >
> > Sent from my iPad
> >
> >> On Jun 18, 2021, at 11:10 PM, w2xj <[hidden email]> wrote:
> >>
> >>
> >> Wayne
> >>
> >> I seriously doubt this is an RF issue. TV is all digital and has no discrete audio carrier. TV RF interference would sound like white noise. This sounds more like an audio ground loop of some sort.
> >>
> >>
> >>
> >>
> >>> On June 18, 2021 10:33 PM Wayne Burdick <[hidden email]> wrote:
> >>>
> >>>
> >>> John,
> >>>
> >>> If the K4 is *off*, then there's no active circuitry involved. However, the headphone plug-insertion detect circuit may involve an IC downstream that could include a schottky diode junction -- a potential way a very strong signal could be rectified right at the radio end of the cable. We're looking at that.
> >>>
> >>> If the cable is not very well shielded, and the TV station is *very strong*, I can imagine modern physics just barely covering this situation. It would help if the headphone cable was about the length of an end-fed dipole at the station's frequency.
> >>>
> >>> As for the K4 chassis itself: It's very well sealed (far better than the K3/K3S).
> >>>
> >>> Wayne
> >>> N6KR
> >>>
> >>>
> >>>
> >>>>> On Jun 18, 2021, at 3:36 PM, John Harper <[hidden email]> wrote:
> >>>>
> >>>> https://www.youtube.com/watch?v=u1XRaNpgQDI
> >>>>
> >>>> John AE5X
> >>>> https://ae5x.blogspot.com
> >>>>
> >>>>> Noticed that when the antenna are disconnected, and the K4 turned off, I hear a local TV station in the headphones… Never happened on the K3.
> >>>> ______________________________________________________________
> >>>
> >>>
> >>> ______________________________________________________________
> >>> 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
> >> 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
> 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

Re: K4 observation

In reply to this post by wa6vab

No difference with or without the microphone: of course, I never had an issue on CW in the first place!

Tom W4KX

From: Ray
Sent: Saturday, June 19, 2021 2:50 PM
To: Wayne Burdick; Tom Doligalski
Cc: Elecraft Reflector; John Harper
Subject: RE: [Elecraft] K4 observation

Did You Trying Transmitting in CW mode with the Mic disconnected ?
WA6VAB ray

From: Wayne Burdick
Sent: Saturday, June 19, 2021 11:41 AM
To: Tom Doligalski
Cc: Elecraft Reflector; John Harper
Subject: Re: [Elecraft] K4 observation

> On Jun 19, 2021, at 3:17 AM, Tom Doligalski <[hidden email]> wrote:
>
> Actually, it could be a radio station. I haven’t listened long enough to ascertain…
>
> Frankly, I don’t care! The bigger problem is the rfi when I transmit.

Which *will* be fixed.

Wayne