[Elecraft] K4 observation

[Tom Doligalski]

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 <w2xj at w2xj.net> 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 <n6kr at elecraft.com> 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 <johnae5x at gmail.com> 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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