[Elecraft] noise

[Don Wilhelm]

Jacek,

I don't think it is a behavior of the K3, but that turning the PS 125 on 
is creating a noise which is somehow being coupled into the K3.  It may 
or may not be a problem with the PS 125.

The noise may be radiated from the PS 125 or it is being conducted into 
the K3 on the power cord or some other cable plugged into the K3.  It is 
also possible that there is a ground loop that is being formed by 
something that is connected to the K3.  It could even be the power 
supply that is connected to the K3 is creating the ground loop by 
connecting the negative power supply output onto the mains safety ground 
(Astron and some other power supplies do that and can cause such trouble).
To find out which, remove all cables from the K3 one at a time (except 
the antenna and power) checking after each one to see if the noise is 
still present - include any ground wires in this test. Finally, if the 
noise is still present, connect the K3 to a shielded dummy load with a 
short length of coax.  If the noise disappears, it is being radiated and 
being picked up by the antenna connected to the K3.
If the noise still persists with only the dummy load attached, it is 
most likely being coupled onto the K3 power cord.  Power the K3 from a 
battery such as a gel cell or automotive type battery to test.  The K3 
should now be completely isolated and the noise should not be present.  
If it is, you can look for the problem in the K3.  Be certain all the 
fasteners in the K3 are securely tightened as a first step.

73,
Don W3FPR 

Jacek Kubiak wrote:
>
> Hi folks,
>
>  
>
> I have noticed strange noise level in my K3 when  switch on my  Icom 
>  756PROII with PC125. When Power supply PS 125 is  switched off again 
> noise  disappear. Is it normal K3 behavior?
>
> How about to use power switching type of supply to K3 in such situation??
>
> Any comments on that??
>
> Jacek Kubiak
>
>