Hi Charles and the group, FB on the numbers. Interesting to say the least and thanks for taking the time to look further into this topic.
Questions? I have a few after looking at these numbers and performing more observations. First, are you testing just the diplexer and not the diplexer and the antenna combined? This could result in an overall number and not just the diplexer alone. How could there be a large discrepency between preliminary reports, 2.65dB and .5dB now. Could be equipment calibration, human error, etc. from previously tested, or attempted testing of the device. I don't believe any improvements have been made to the Arrow diplexer, but who knows? Second, I switched back to the Arrow diplexer and made another comparison with the Comet diplexer. Again, no comparison, the Comet outperformed. Why would this happen if the two are pretty close to one another in numbers. The Comet has .25db loss at VHF and .26 at UHF. Third, with the Arrow diplexer I wouldn't begin to receive the birds until almost 3 minutes after AOS, with the Comet diplexer a minute to 1.5 minutes after AOS. Yes, watch calibrated to WWV and multiple times of acquiring the birds. I've tried both setups with the HT and D710 and they both show the same results respectively, Arrow diplexer vs. Comet diplexer. The antenna and coax remain the same, the difference, the diplexer. May not be test lab quality but something is proving itself. What is it? Finally, is it just my Arrow diplexer? Doesn't appear to be shorted or any defects to it. Actually looks great and assembled very well. I've encountered others saying the same thing. However, a very noticable difference to the overall performance. 73, Jeff WB3JFS ----- Original Message ----- From: Charles Suprin To: Jeff Yanko Cc: Joe ; Gary "Joe" Mayfield ; AMSAT-BB Sent: Thursday, October 01, 2009 1:09 PM Subject: Re: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE 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
