Has anyone played with Kent's idea of insulating the elements from the boom?
73, Joe kk0sd -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Robertson Sent: Friday, September 25, 2009 8:53 AM To: Jeff Yanko Cc: AMSAT-BB Subject: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE Jeff -- I really appreciate you doing this research for us. Two additional ideas come to mind: 1. Those of us with FT-817s could configure its two RF ports to use different bands and connect the rig directly to the beam's antenna connectors, bypassing the duplexer. For this purpose, higher-quality bnc terminated cable would be useful. 2. If I'm correct, your replacement duplexer is rather larger than the one it is replacing. It would be a great topic for a Journal article if someone with the necessary equipment and expertise were to design a replacement with less loss. 73, Bruce VE9QRP On Fri, Sep 25, 2009 at 6:10 AM, Jeff Yanko <[email protected]> wrote: > Hi all, > > A quick update to my new project to improving the Arrow antenna, efficiency > wise. I wanted to see how well it would perform on gaining and losing > access during AOS and LOS. AO-27 is not a good choice since the timer is > turned on when it is well above the AOS horizon and it is switched off > before it reaches its LOS horizon. That leaves a dependable AO-51 to test > it out. > > With the last setup, the OEM diplexer provided by Arrow Antenna, I would > copy AO-51 about 3 minutes after AOS and lose it about 3 to 4 minutes before > LOS. Not bad, but people were saying they worked the birds when they were 1 > degree off of the horizon. I have some pine trees that could be an issue > but they are spaced far enough apart that I can work between them and I also > have to deal with the McCollough Range to the SSE of me here in Las Vegas, > NV. Today, there were 2 passes of AO-51, one at 12 degrees elevation, the > other at 74 degrees. During both passes, I began to copy the downlink about > a 1.25 minute after AOS. A considerable difference from 3 minutes. The > downlink also improved down to about minute before LOS. On the last pass I > worked KG6NUB at 0124z and LOS was 0125z and my downlink sounded fairly > good, though I was fighting desense. (That's another issue I need to > resolve.) Also, on both passes, I never once lost the downlink. No > dropouts or fades. I'm still amazed. > > Another issue I came across was how wide the beamwidth is of the Arrow > Antenna between the Arrow diplexer and the new diplexer. I was wondering if > this was going to happen and it did. The reason that this happened was with > the old diplexer, the signal attenuated so much that you had to be pointed > right smack dab on the bird, a few degrees off and you lost the signal. > Now, with the new diplexer, you can point the beam in the general direction > and still copy the bird. In most cases I had to turn the beam 90 degrees > before I completely lost the downlink! Twisting the antenna to make > polarization changes makes absolutely no difference now. This also > attributes to the fact that now I'm copying the entire pass without dropouts > or fades. Makes sense. What I've regained over the lossy diplexer makes up > for any polarization differences, etc. for a better copiable signal. > > Next weekend I will have to try more passes and get a feel of how much this > system has changed. > > > 73, > > Jeff WB3JFS > Las Vegas, NV > DM26 > > > > > > > _______________________________________________ > Sent via [email protected]. 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 > _______________________________________________ Sent via [email protected]. 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 _______________________________________________ Sent via [email protected]. 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
