Howdy Jeff, Someone asked and here we go. A file attachment follows.
Actually the diplexer looks pretty good. Less than half a db of loss at VHF and around half a dB at UHF. I checked the calibration and that was within tenth of a dB over the entire range. Any questions. Charles AA1VS On Sat, Sep 26, 2009 at 6:26 AM, Jeff Yanko <[email protected]> wrote: > Hi Joe and all, > > I doubt if the Arrow diplexer has 20dB of loss. If it did, we'd never > receive a signal! :) > > I believe somebody here on the -bb will be performing a test on the Arrow > diplexer using a vector/network analyzer. It will be interesting to say > the > least. There were preliminary reports saying the device had a loss > anywhere > from 2.65 to 2.80dB. That's close enough to 3dB which is technically half > power loss. Add the loss of a short piece of coax and it will certainly be > pushed over the 3dB line. > > If I recall correctly, cross polarity is also a 3dB loss. I have noticed > that when I rotate the antenna I might get a stronger downlink but I never > lose it when I rotate it back. Before, when I would do that it would drop > once I rotated in either direction from the peak signal. Basically what is > going on is the lossy device is removed and replaced with a more efficient > one, that extra net gain you just boosted now shows how the system on the > antenna side of the diplexer is truly performing. > > I don't have an antenna analysis program to perform a test, but what does a > 7 element 440 yagi pattern look like and what is its overall gain? > > What we need to do is break down the antenna configuration into 3 segments, > see what their losses and gains are then combine them for the overall > figure. The 3 segment would be the antenna, the diplexer and the coax. > Each one will be tested individually to give an accurate number for each. > > > 73, > > > Jeff WB3JFS > ----- Original Message ----- > From: "Joe" <[email protected]> > To: "Gary "Joe" Mayfield" <[email protected]> > Cc: "'AMSAT-BB'" <[email protected]> > Sent: Friday, September 25, 2009 6:42 PM > Subject: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE > > > > as in the texts below, there is something else going on here. > > > > That Diplexor can not be all that bad. two reasons. > > > > How many db down is the front to side of that antenna? > > > > and I can not imaging someone would sell a diplexor that has greater > > than 20 db of losses. > > > > because of the statement that how criticalpolarity was with the > > original, and now the antenna has to be nearly 90 degrees cross > > polarized to make it drop out uhh > > > > that close to 30 db, > > > > at least 20,, > > > > something else is going on here > > > > Gary "Joe" Mayfield wrote: > > > >>> > >>>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 > >> > >> > >> > >>------------------------------------------------------------------------ > >> > >> > >>No virus found in this incoming message. > >>Checked by AVG - www.avg.com > >>Version: 8.5.416 / Virus Database: 270.13.113/2395 - Release Date: > >>09/25/09 17:52:00 > >> > >> > >> > > _______________________________________________ > > 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
