[Elecraft] SDR-IF and I/Q questions

[Richard Fjeld]

Larry,  (Reply to message 12, 16 Nov 2011)

Yes, I have the XG2 generator for portable use, and another gen in a IFR1500 I can use.

I wrote down the test levels when I tested the SoftRock w/Z10,000 but
I don't remember them. I hope I can find the notes easily.

I found this interesting: ("As the number of signals goes down, 
the required strength of the signals goes up")

I DO understand the last part of the paragraph, 
but I have a question about this: ("We use -50dBm (S9+23dB) in the 
shop to check out LP-PANs before shipping")  

What is the ratio of input to output level?  And better yet, what is the input level 
you expect  to see from the IF of a radio on average?  I'm curious.  

Thanks again, 
Dick, n0ce

____________________________________________-
You might want to consider buying an XG2 test generator kit from 
Elecraft. It would help a lot to have a signal of known level to adjust 
your overall gain. It would also help with image rejection adjustment, 
although a single carrier at S9 is a tad low for WBIR to work reliably. 
WBIR assumes a lot of medium strength signals. As the number of signals 
goes down, the required strength of the signals goes up. We use -50dBm 
(S9+23dB) in the shop to check out LP-PANs before shipping. WBIR takes 
about 10 seconds to find an initial null at this level. The image drops 
to about -130dBm. If you set your overall gain so that you get a -73dBm 
blip with the K3 preamp OFF, that would give you about -62dBm with the 
preamp ON. You can get the extra gain by changing the gain setting 
resistor on the Z10000, or increasing the sound card gain. If your K3 
does not have the buffer mod, that would be a good idea to add as well.

73,
Larry N8LP