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The Legend of Moby Click!

05 Dec

As legends go, this will be a modest one. Nothing on the order of Ichabod Crane or Paul Bunyan. Yet, in its’ own domain, Moby Click annoys and entertains with the best of them.

Every year I partake of a few radio contests. Some years, as in 20 years or more ago, the number was high and sometimes I even traveled to participate, as I did to Monserrate and later to St Martin. However, of late it has been all from my home. This year was a trial run to asses any changes in station performance due to work completed in late summer on my modest antennas and noise abatement program. You see a contest presents a wonderful opportunity to compare station performance alongside some of the best equipped stations in the world.

This year I was particularly keen to see how well I could hear. Specifically, I was looking for stations from rare spots on the globe that were being ignored or remained unheard by other, more powerful and better equipped stations. The mechanism I am trying to evaluate is to see if effort expended to reduce station local noise levels pay off as well as spending money on better antennas. If I can hear things others ignore even though equipped with better antennas I am cash ahead. I realize that this only applies to receive and does nothing for my transmitted signal but work done now will remain should I chose to improve my antenna in the future. When I began my quest to improve my noise floor it was a horrendous S-7 in AM wide mode. Applying about a years worth of trial and error, lessons learned from my Elmer and shagging around my home with a shortwave receiver and a magnetic receiving loop all produced results. A cursory check on some bands some of the time reveals a current state of S-3 with occasional excursions to S-0 in AM wide mode. This depends on Time of Day and noise sources outside my control. Still, a 4 S unit improvement in received noise floor is at least equivalent to a small tribander at 40 feet-admittedly a SWAG on my part but impressive nonetheless.

I operated in the contest for about 12 hours on two successive days. Normally these things take up a block of 48 hours. I had neither the stamina nor the inclination to spend that much time operating. I spent my time looking for very weak stations in populated portions of the bands and monitoring the stations activity. Should the station I am listening to go ignored for very long I would try to make contact. More often than not I would be successful. Generally I became aware that I was able on lots of occasions to work stations others would not try for or simply didn’t hear.

Noise abatement is an iterative process. It is frustrating on one hand because incremental changes do not produce staggeringly positive and immediate results. It is sort of like layering one set of installation principles on top of the next and then the next. After 1 plus years of trying I can say it has been well worth the effort. I still have more ground to cover in my quest.

During the contest one thing became very apparent: Moby Click lives! Moby Click is a phenomenon known as key clicks and cannot be tamed with any receiver technology. You see, Moby Baby is transmitted artifacts which interfere with adjacent channels and are in your received passband and you cannot do a thing about their presence. You will be stuck with them. Seemingly reasonable persons operating reasonable stations are prone to hang a 10 db amplifier on a malfunctioning exciter and create the dreaded Moby Click. It got so bad I began logging the worst offenders. The optimist in me assumes that these fellows know nothing of their transgressions. I wish there were a way to nudge these fellows, but attempting to let someone know their signal is bad is like telling someone their grandchildren are ugly. It just never seems to work out to a mutual satisfaction.

Just a suggestion if you are so inclined:

  • keep your ALC low enough to not lose power output. Never any more than that.
  • If in doubt; ask your QSO mate to listen off frequency as a test.
  • Be receptive to constructive criticism.

Thanks and have a great day! Chas.

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Posted by on December 5, 2007 in Radio

 

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