FW: [Elecraft] Spectrogram plot interpetation

Sat Jan 3 13:45:01 2004

I have that same spike there. It goes away when I unplug the power
supply and run on the internal battery.

The large spike is at 120 Hz, and there is a much smaller one at 60
Hz. Need more filtering on the power supply. Or could just put a large
electrolytic in some spare space in the K2. Think it only affects the
receive audio. Have never seen a 120 Hz artifact on the transmitted
signal.

73, Guy

----- Original Message ----- 
From: "Don Wilhelm" <[email protected]>
To: "Dan Barker" <[email protected]>; "Elecraft"
<[email protected]>; "Tom Hammond" <[email protected]>
Sent: Saturday, January 03, 2004 12:30 PM
Subject: Re: FW: [Elecraft] Spectrogram plot interpetation

> Tom, Dan and all,
>
> I too looked at it and thought nothing of it.  I just figured it was
the
> 'zero frequency' response of the Fourier transform which is
mathematically
> undefined at zero frequency.  Most all spectrum analyzers show
something
> going toward infinity at the zero frequency edge.
>
> There could be some 60 Hz hum there too, and if so, I would expect
it to be
> from pickup on the wire used between the K2 and the computer - we
don't know
> if a good shielded cable was used or not.
>
> In any case, it is NOT coming from the K2.
>
> 73,
> Don W3FPR
>
> ----- Original Message -----
> >
> > I believe that to be an artifact of Spectrogram and the sound
card! I've
> > noticed something similar in just about every Spectrogram
presentation
> I've
> > seen. I do not believe it to be present IN the K2, or whatever rig
is
> being
> > tested.
> >
>
>
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