[TowerTalk] Interesting development

Jim Brown jim at audiosystemsgroup.com
Mon Sep 30 22:44:25 EDT 2013


On 9/30/2013 6:22 PM, Big Don wrote:
> This effect might explain the phenomenon of "working someone on your dummy
> load."

Yes.  I worked CQWW RTTY QRP (5 watts).  I made QSOs with 42 countries 
(MUCH harder from California than from the east coast), including 20 
countries in EU. Doing the math, that's 25 dB down from 1.5 kW, which 
corresponds to more than 4 S-units on a REAL S-meter. I say "real" 
because although 1 S-unit is supposed to be 6 dB, most S-meters are so 
poorly calibrated that once you get below about S7, an S-unit is usually 
only 3-4 dB.

No surprise that you saw signals change as your turned your antenna -- 
it's quite common for antennas to interact with each other, and in ways 
that might surprise you.  Consider, for example, that an antenna with a 
24 ft boom is resonant on 15M, so when it's boom is parallel to the 
elements of the other antenna, it will act as a parastic element on 15M, 
and that boom will radiate. The same sore of interaction happens with a 
40M antenna and a 15M antenna -- as you change the relationship between 
them, you can see the pattern of the 15M antenna change.  It's quite 
instructive to model stuff like this in NEC. :)

73, Jim K9YC


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