[DSP-10] Noise Figure (finally) measured.

[Courtney Duncan]

My noise source was built, works fine, and was calibrated at NoiseCom  
in May.  Today I finally got to measuring the receiver performance of  
the DSP-10.

Using F = ENR / (Y - 1) with Y = (noise on) / (noise off) calculation  
did several measurements using several calibrated fixed attenuators in  
the setup.  Also compared the direct measurement to one done with all  
of the amplifiers and the Bird wattmeter in line.  The results across  
all tests are consistent, about 12.0 dB, that is 4300 K.

This is somewhat higher than I was expecting so I scrutinized Sabin's  
article and the equations and played with them in a spreadsheet until  
I decided they are probably right.

I was expecting more like 600K - 1000K for this.  It's no wonder I'm  
not seeing EME2 as quickly as expected, even at 70 watts, but I'm  
wondering now how I ever saw anything at 7 watts, even with 10,000~  
seconds of integration.

Certainly, a nice low noise preamp is higher on the list now.

Continuing to investigate.  Anyone have any ideas?

Courtney, n5bf/6