[Elecraft] K2 - Adjusting L34 with Spectrogram

[Don Wilhelm]

JT,

Turn the AF gain (or the soundcard line-in setting) up a bit until the 
noise in the passband becomes a bit greater.  After that, adjust L34 for 
the greatest difference between the signal and the noise floor.
Expect some difficulty in determining the proper point - the peak S/N 
ratio is still quite broad.  If you do not discern any improvement, just 
set the slug for the greatest amplitude on the Spectrogram display and 
be done with it. 

If you cannot discern the difference in S/N ratio with either your ears 
or with the Spectrogram display, then the setting that gives the 
greatest amplitude is the correct one (and it is a broad setting).  If 
your 'best' setting is very far from 1 to 2 turns from the top of the 
coil, then check things again because something is wrong (most likely a 
soldering problem).

The spike is likely a result of pickup from some local source - check 
the things in your house as a first course of action.

73,
Don W3FPR

JT Croteau wrote:
> Decided to try pre-aligning L34 using Spectrogram.  However, I've
> never played with Spectrogram or anything of the like before.
>
> This screenshot shows the best Signal to Noise ratio I could come up
> with.  Does this look about right?
>
> http://tinyurl.com/3bd3m2
>
> Internal signal was found right at 7 MHz and I have FL1 (1.50)
> selected per the recommendation of KE0Z.  The -53 dB spike at ~1152 Hz
> is oddly interesting to me, is this normal?
>
>