[amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE
Jeff Yanko
wb3jfs at cox.net
Fri Oct 2 23:26:38 PDT 2009
Could very well be.
73,
Jeff WB3JFS
----- Original Message -----
From: "Gary "Joe" Mayfield" <gary_mayfield at hotmail.com>
To: "'Jeff Yanko'" <wb3jfs at cox.net>; "'Charles Suprin'" <hamaa1vs at gmail.com>
Cc: "'Joe'" <nss at mwt.net>; "'AMSAT-BB'" <amsat-bb at AMSAT.Org>
Sent: Friday, October 02, 2009 6:27 PM
Subject: RE: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE
> We are missing the easy answer. He had diplexer that was off spec. It
> happens.
>
> 73,
> Joe kk0sd
>
> -----Original Message-----
> From: amsat-bb-bounces at AMSAT.Org [mailto:amsat-bb-bounces at AMSAT.Org] On
> Behalf Of Jeff Yanko
> Sent: Thursday, October 01, 2009 4:28 PM
> To: Charles Suprin
> Cc: Joe; AMSAT-BB; Gary "Joe" Mayfield
> Subject: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE
>
> 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 <wb3jfs at cox.net> 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" <nss at mwt.net>
> To: "Gary "Joe" Mayfield" <gary_mayfield at hotmail.com>
> Cc: "'AMSAT-BB'" <amsat-bb at amsat.org>
> 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
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>_______________________________________________
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