[Elecraft] lsb usb different in spetrogram- why ?

[Don Wilhelm]

Wolf,

That is NOT normal, but I don't think it is a problem on the SSB board.
The filter passbands should be approximate mirror images.  Your BFO settings
are correct since the passband looks to be centered between 300 and 2300 Hz.

You might want to re-check the setting of L34 - it will have an effect on
the flatness of the passband.  Also check the component values of the 2nd
filter flattening mod - (either the original 120 pf capacitor or the later
100 pf capacitor AND 5600 ohm resistor across the product detector output).

Were you using the headphone output or the external speaker output to drive
the soundcard.  The headphone output will attenuate the high frequencies, so
use the external speaker jack for the best indication.  If you end up
adjusting L34, the correct setting will be for the slug to be 1 to 2 turns
down from the top.  L34 can be adjusted for a compromise flattness between
the LSB and USB curves.

73,
Don W3FPR

----- Original Message ----- 

> Hello,
> Today I adjusted again my filters with spectrogram. Later today I will
> made the BFOmod and the PLL upgrade.
> I see 2 different filter curves. USB is much more worse than LSB, because
> of the over 10dB difference between 1khz and 2khz. LSB looks fine.
> I have made two screenshots.
> http://www.dl2wrj.de/misc/lsb.jpg
> http://www.dl2wrj.de/misc/usb.jpg
>
> Is this normal or is there a possible failure on my SSB board?
>