I know there has been lots of discussion but I just made a change which
solved everything. I noticed that the peak was at the top most rotation of
L34, so I changed C182 from 180pf to 120 pf (npo). Now, using an external
sig gen, not the 7k birdie, there is a pronounced peak about halfway down
L34.
On 8/29/07, Don Wilhelm <[EMAIL PROTECTED]> wrote:
> You really should crank in a bit more soundcard gain - that will allow
> you to see the noise floor across the entire screen rather than just in
> the passband. That is often helpful in making an overall judgment.
I'm going to experiment with a
JT,
Those all look good, but really do not tell us much - you have to be the
judge of when the peak of the signal has the greatest difference to the
noise floor.
You really should crank in a bit more soundcard gain - that will allow
you to see the noise floor across the entire screen rather
It looks like I goofed in my last screen captures. Here are some new
shots, one for each filter setting, of my tweaking L34 with
Spectrogram.
1.5 kHz Filter:
http://tinyurl.com/2rla5d
700 Hz
http://tinyurl.com/2k9p7f
400 Hz
http://tinyurl.com/2lrr8p
200 Hz
http://tinyurl.com/3dyj37
I haven't
On 8/28/07, Michael J Carter <[EMAIL PROTECTED]> wrote:
> Could the weak(-53 dB) spike just be 2nd harmonic of the audio
> fundamental spike?
No, it was a spurious emission from something but I'm not sure what.
My latest experiment of playing with L34 and SG is much cleaner:
http://tinyurl.com/26
JT and Don,
Could the weak(-53 dB) spike just be 2nd harmonic of the audio
fundamental spike? The main spike looks a bit lower than 600 Hz?
Just a thought to save looking for another source of the spurious
signal.
73,
Mike, K8CN
K2 #5569
Quoting Don Wilhelm <[EMAIL PROTECTED]>:
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 sti
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 M
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