I have been surprised that no one has been talking about the
performance of the SR40.
It has brick wall filters, really nice. I have mixed feeling about
the noise reduction, but not sure I understand the NR operation so
will withhold comments.
I have not really had problems with 7056 khz osc noise, but I got
rid of the USB power source very quickly. 78L05 is the way to go.
I run it with a laptop and distance improves the operation. Laptops
generate a lot of EMI. Connect your SR40 to a dummy load and then
fight your EMI sources. I have three different laptops, different
brands but they all radiate. Next week I hope to move the SR40
connection to my 800 mhz tower with a Delta 44 and see how it does
with weak signals. I ended up with my SR40 in a die case box. Some
of those signals you see in the pass band may be your own computer.
Watch out for ground loops. The SR40 is a RF device and you know
the rules, one ground return for everything.
Do learn how to use your mouse for tuning. Do not over drive the
soundcard. Click on some of those -90 db signals and use the
filters. You will be surprised if you have been using the old 602
mixer qrp rigs. I have been able to copy -110 db signals very well.
Takes a little practice to learn how to use the powerful software.
A good ham band band pass tuner in front of the receiver would be
nice, most of the antenna tuners are LPF designs and not much help.
But not required for a fun experience.
Stan AK0B
