[amsat-bb] Re: Quadrifilar Helix antenna question
mryan301 at comcast.net
Mon Jan 23 19:04:26 PST 2012
if youre referring to the Quadfilarconstruct.zip file on the skydrive, that’s actually the instructions I tried to follow. used the recommended hardline and everything. Perhaps I missed something or am just too clumsy in my construction.
From: Dave Guimont
Sent: Monday, January 23, 2012 6:28 PM
To: Mike Ryan
Cc: amsat-bb at amsat.org
Subject: Re: [amsat-bb] Re: Quadrifilar Helix antenna question
or if you wish call me at 619 275 1495 before 1800 pacific....I'm in San Diego...
Try my QFH...Many others have built them (years ago!!), and found them successful...BUT at 435 measure the filars +-1/64, and be careful with solder joints...and use teflon for the coaxial filar.....and I guess obviously, "N" connectors......the connector is the most expensive part of the antenna.
I have a friend that lives on a sailboat and bought some expensive commercial antenna, and the one he built from my dimensions outperforms it....
QFH are a bear to build, especially on 70 cm unless youâre very , very skilled. I tried 3 times and failed 3 times. Finally gave up and went with a standard turnstyle. Still critical tolerances but much easier to make and works lower on the horizon than the QFH. QHtenna used to sell turnstiles (reviewed in QST) but I think they are out of business now. You might also want to consider a moxon. Cebik wrote a nice article on making a moxon based turnstile. I built one for 70 cm using PVC and like the QFH and eggbeater (with reflector) , it works best on higher passes. If you run out of patience, you might consider the Antennas.us QFH. It was also reviewed positively in QST but I donât own one. And lastly, omnis are small and simple, but you really need a preamp to avoid a terminal case of frustration. I use the ones from ARR with good results. Mike _______________________________________________ Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
73, Dave, WB6LLO
dguimon1 at san.rr.com
Disagree: I learn....
Pulling for P3E...
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