[NLRS] Deafness on 6M

[Dr. Gerald N. Johnson, electrical engineer]

It might be worth installing a polarization rotor so that the cross
polarization null can be tweaked. I had a polarization rotor on a 2m
beam once and the notch was quite deep and quite narrow on the local
repeater. Hope that the TV station isn't running circular polarization
to get better quality signals to TV sets using single whips.

I have observed that cross polarization loss can be significant on 10m
so I expect it will be similar on 6m. At one time my dad and I had a
three element beam horizontally polarized with a quarter wave whip above
it with a relay to select which one was connected to the coax. Many
times when the horizontally polarized signal took a fade I found it was
just coming up on the vertical and would stay there and when it faded on
the vertical it was just coming back from the horizontal fade. I'm not
convinced that going vertical on 6m for sporadic E or tropo is a good
idea. 40 dB of channel 2 attenuation accompanied by that much signal
attenuation isn't progress. Notice the limited range for contacts on SSB
when using the handy 2m FM colinear.

The noise in the 50 MHz region should be more than 70 dB down, but 100
dB down from 100KW ERP is still a strong signal to a weak signal
receiver.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.