Firsts tests were done using the Thinkpad internal sound-card  (not suitable)  and before reading documentation...

I will not translate everything but it was not much successfull.  Having the impression of a receiver (with noise... as if) but only receiving big stations  (radio Beijing...)  everywhere in the dial, at places they are not.
Also tried various softwares.

Then I used an external sound card  E-MU 0204

Connecting:

- Sound Card device is connected to PC via USB cable
- SDR is connected to PC via USB cable
- SDR is connected to sound card input via a stereo Jack cable  (actually 2 Jack connectors on soundcard side)
- SDR is connected to antenna (I use a 2 x 6m dipole approx)

SW:
Install the soundcard pilot.

Initally I was launching SOFT66LC4 control program (will find later it's better not to use it but extio DLL instead)  , then external sw.

Got something but I did not understand anything about the frequency I was on, which has little interest for a receiver...

After some time I tried again. Here is what is working:

- I do NOT launch SOFT66LC4 anymore
- I use  G8JCFSDR
- Setup :  SDR Model : Soft66ADD(EXTIO)
             input soundcard : E-MU 0204
             output soundcard : The one from the PC
 

Frequency is adjusted from the software.

This seems to work quite well , except that...    Every signal seems to be duplicated 24 kHz below its frequency.

A broadcast on 3965 kHz is also received on 3941 kHz (screenshot)
A broadcast on 11635 kHz is also received on 11611 kHz (screenshot)
etc
quite confusing.

Also for DRM   (launch DREAM after  G8JCFSDR),  the "image" signal is the one that is decoded properly.  The original correct frequency is not decoded.

All India Radio on 9950 kHz is not decoded on 9950 kHz but is received on  9926 kHz ! (screenshot)
Same for Romania on  9780 kHz which is only decoded on  9756 kHz.  (screenshot)
This was later solved by ticking the "Flip input spectrum" button on Dream..

The Image (non) rejection was solved after some exchanges on YahooGroup G8JCFSDR
and also some reading... It directly depends on the quality of the input I / Q signals.
This is where I had something wrong.

The important items to review are:
- Quality of the connection between the SDR and the soundcard, bringing signals I and Q to the two
stereo inputs of the soundcard .  Ensure all is wired properly
 Also I finally used thye two 6.3 jack inputs.
- The soundcard MUST be set to STEREO   (frontside button)
- Levels must be correctly set and balanced
- Level setting on the SDR itself must also be correct
If for any reason only one of the channels is connected  (R ou L), you will still have output
giving you the feeling it's working.  But there is NO image rejection  (no proper I Q input)
Same if you are set to mono.
- With G8JCF SDR, soundcard sampling rate must not be more than 48 kHz
  (seems software will anyway be hanging if you try to set a higher value)
 

Among the tests you can do, tune to a powerfull local station, then set the spectrum scope 
to Soundcard input, and set the scope mode to Phase. You should see some kind of circle/disk 
if the input is proper I/Q.

If you unplug I or Q inputs, you will see a horizontal or a vertical bar
If you input a square calibration signal, the Phase mode would show a Square rotating slowly in the 
centre of the scope display.  If you look at the signal using Time mode, you should see the 90 degree 
phase shift.

After reviewing and adjusting all that  (as well as R / L signal level setting on frontside), my
image rejection was much better !!!

See the  "Log" page for further tests.

15/04/2013:
But... future says that if you touch some settings, you are easily back to previous situation (bad I/Q).
Next step is to put in writing the difference settings for both cards, and their respective role.
You have a level setting on the SDR  (not practical), you have level buttons on the external soundcards,
and you have all the Windows audio settings.
If you do some decoding without the SDR and change some settings, when you come back to the 
SDR, it may not be properly set...
For instance when checking VOA's radiogram on 14/04 i noticed the signal level from SDR (on that frq at 
that time) was weaker compared to a TS480 with same antenna.  So I will have to go thru all
the SDR level settings again.