[Skimmertalk] Evaluating different skimmer hardware

[Mark n2qt]

I found that using an Elecraft xg3 was handy for evaluating skimmer setups.

I was trying to see what sound cards worked best with my 6M soft rock. It was possible but
tedious to do a regular receive sensitivity test so I programmed an xg3 to send Cq twice
and then change frequency by 10 kHz and repeat. An external step attenuators was used
to further drop the xg3 output to where the lack of great shielding showed more incidental
radiation getting to the receiver.  (Using higher input levels also lets you see how effective
the I/Q balance is in reducing images). 

By saving the skimmer output as recorded over a telnet connection a series of SN readings
were available to compare the two sound cards over the 192 or 96 kHz range, and various
level settings. It was easy to see the sensitivity drop off at the edges and other variations.

This might be a good way to compare other hardware configurations in a more controlled
environment.  I didn't write a macro to drive the xg3 as my testing was so limited, but it
should be possible to run this test pretty much hands off.  

Of course this doesn't cover the possible influence of BC or SW broadcast stations or
other local interfering signals.

Mark n2qt