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[TowerTalk] Add a dose of common sense

Subject: [TowerTalk] Add a dose of common sense
Date: Wed, 23 Jun 2004 09:54:28 EDT
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The LPDA Vs F12 Vs Steppir thread begs for some common sense. Each  offers a 
compromise because most hams can't erect monobanders on separate towers  for 
each band. So which compromise is better? Depends. (how's that for muddying  
the water?).
I have 4 towers and a number of monobanders (plus 40 years of building  
contest stations), so I have points of direct reference.
I have a F-12 EF340D, 3 element 40. It replaced a Cushcraft 402D that was  
destroyed when the antenna above it failed and came crashing down. 10' above 
 40 is a Mosley Classic 33. The EF340D, with the alumi-weld linear  loading, 
gave K6ZM years of flawless performance in an environment where there  was no 
snow or ice. It has failed two of the last two winters at my QTH from  wind 
and ice. I am replacing it with a C39XRN which has F12's newest (and much  
heavier duty) linear loading on the 40 meter elements.
Common sense: The stack seemed like a good idea, but the CL33 never really  
performed because it is a high-Q trapped antenna too close to the 40m beam. The 
 40m beam was a killer but wouldn't stay up in our winters. The C39XRN 
appears to  be the common-sense solution. Stay tuned.
I have a PRO 57B on another tower that is used as a backup antenna and on  17 
and 12M. Again, it is a very high Q trapped antenna and is detuned by nearby  
Vee beam and other wire antennas. While it is only slightly down in gain from 
an  optimized 4 el 20 on another tower, it is not meeting my needs due to 
erratic  SWR changes as I turn it around the wire antennas. I am replacing it 
with a  Tennadyne T-12 LPDA.
Common sense: While an LPDA is a compromise, it is a low Q antenna and my  
expectations are that it will compare favorably with the monobanders and not 
 the wire antennas. Stay tuned.
I have a F 12 C31XR on yet another tower. It is hard to tell any difference  
between it and the 4 element 20 and 5 element 10 monobanders. It made it 
through  the winter with flying colors and is my main antenna until the others 
Common sense: The F-12 multi-monoband design is the least lossy compromise  
in conventional yagis. The radical element and boom taper schedules are largely 
 responsible for their resilience in poor weather.
As for the SteppIR. Don't have one and don't want one, only because I have  
been bit in the past buying serial #1. 30 years ago, the Kirk helically wound  
fiberglass beam seemed to be the solution to a short 40. Unfortunately, over  
time, they did not stand up in weather and UV.
Common sense: SteppIR looks like a great solution, but cautious  optimism 
needs to prevail until there is several years of survival history in  many 
different operating environments.
Common sense summary: Read, ask and evaluate your objectives. Try what you  
think is best. If it stayed up last winter it wasn't big enough. You can never  
be loud enough, that's why summers are made for fixing weather damage and  
changing antenna configurations. Enjoy the journey.
Tom, K5RC
Virginia City NV

See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

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