Monday, November 28, 2016

8Q7DV and Flex 6700 Diversity

Tonight I worked 8Q7DV out in the Indian ocean on 40M.  I was listening to 80M but could just tell he was in there.  He came up on 40M was quite respectable.  My 40M band noise is about -110 dBm tonight and 8Q7DV was -105dBm.  I got him simplex in 1 call, and he soon went split

It was just at sundown and the terminator was flying over my head.

I decided to make a quick video to demonstrate diversity on the 6700.  The 6700 creates a true spatial diversity between the 2 receivers.  Its intent is to reduce fading.  It is not beam forming like the F5K or the Anan.  Those systems are not true diversity but accept one signal as I and the other signal as Q and then creates a plane of points with variable intensity and phase therefore creating a cardioid pattern.  The Flex uses 2 signals which have relative independence with each other but are coherent and the signal is presented to the brain in a way that reduces fading.  

You can see the diversity slice is slice H in the above pic and it has adjustment available for AGC-T audio AGC period (fast med slow) and the DSP functions.  The bandwidth is matched on the 2 receivers and one RX is placed in the right ear and the other in the left.  My antennas are a vertical a G5RV up about 55 ft and a Wellbrook ALA-100 loop.  The dipole and the vertical are separated by about 170 ft and the vertical and loop by about 100 ft.  The 6700 antenna switch is powerful enough to  allow for up to 5 receiving antennas in a multiplicity of combinations so there are many permutations possible depending on your space.  I made a video  demonstrating.  There wasn't a huge amount of fading on this station, but the system does make station readability more stable.


73  W9OY