[Elecraft] SDR-IF and I/Q questions

[Larry Phipps]

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



On 11/15/2011 11:01 PM, elecraft-request at mailman.qth.net wrote:
> Date: Tue, 15 Nov 2011 13:21:24 -0600
> From: "Richard Fjeld"<rpfjeld at embarqmail.com>
> Subject: [Elecraft]  SDR-IF and I/Q questions
> To: "elecraft posting"<elecraft at mailman.qth.net>
> Message-ID:<423B456D46A04B79A8646FDD9820B2B2 at BIOSTAR>
> Content-Type: text/plain;	charset="Windows-1252"
>
> Larry,
> Thank you for the suggestion. That could be possible. I'd hate to remove the Z10,000
> Buffer/Amp to change out a SMD component, but that may be what I will have to do.
> My Z10,000 is set for 0 dB gain at present.  I just e-mailed the Google PSDR-IF group
> a question about an observation I have made. It may be totally in the wrong pew, but
> you may want to look for it. And, it may reveal something I am doing wrong.
>
> Thanks,
>
> Dick, n0ce