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?
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