[amsat-bb] Arrow Diplexer loss + Arrow v Elk

[KI6RRQ]

Jeff, you said; "The antenna and coax remain the same, the difference, the
diplexer."  

My Arrow diplexer has three factory fixed wires coming out of it, one for
the radio and two that go to BNC connectors on the Arrow antenna.   So, you
cannot say; the coax remains the same!   The coax on your diplexer or the
connections to it, can be at fault as well.  These coax wires and how well
they are connected to the Arrow diplexer, are another variable that you have
not considered in your statement because they are removed from the mix when
using the Elk, unless you are trying to use the Arrow diplexer on the Elk
Log Periodic antenna, Which I doubt because I am assuming you used the same
one radio configuration on the Elk as you did the Arrow with your diplexer
but if you are that could be presenting some other variables to produce the
results your experiencing.   You have to use different cables for your Comet
Duplexer on the Arrow, from the Comet, to the antenna connection. 

Although, I agree that the Arrow seems to pick up the signal a little later
then my Elk antenna, both antennas work pretty darn good, IMO.  I like them
both and recommend them both.   I do not have a technical background so my
comments here, are all anecdotal in nature but the other thing I have
noticed between the two antennas, is that when I make terrestrial contacts
with them, the Elk appears to radiate almost as well toward the back, as
toward the front.  I have been told this is called front to back ratio.   If
I point north, a guy from the south calls back and I tell him, wow I am
pointed north, let me turn and point it toward you.......any better.... And
usually there is little if any improvement, while on the Elk and what blows
my mind is, there is also a fair bit of response from people even 90 degrees
from the business end of the Elk.   I have tried the same with the Arrow and
gotten much different reports.  This is only a general statement; I think
the Arrow has a better front to back ratio, more energy going out the front
end but I know there are other variables such as; hand held or up on the
tripod I use to hold them each up (at times) and perhaps the ground under
me, or the moisture in the ground during the different attempts, etc.  (4-5'
above the ground on tripod and me not always right behind it, so plenty of
variables but in general, that is my experience in the field) 

Nevertheless, I have mentioned this to several on the board who have the
Elk's and no one has responded that they have tested there's in this regard,
so take this with a grain of salt for now.  To others, I would love to hear
your experience in this regard.   I have asked a capable HAM friend to help
me figure this out, properly, so one day I will have more then anecdotal
info. 

I think both antennas are very well built and work well for satellite and
emergency communications!    I have often pulled one of them out, with
success, when band conditions would not allow an Omni to get the job done on
my VX-7R.  I found the Elk a little cheaper to buy unless you do not
purchase the Arrow diplexer.  For others I will point out that, you can use
the Arrow with two radios without a duplexer, with same two radio
configuration, you will need a duplexer for the Elk and of course the
reverse is true if you are using one radio for dual band work, as I do, the
Arrow will require a duplexer and the Elk will not.  Also as many of you
know the Arrow diplexer is only rated for 10 watts but without it both
antennas will handle much more.

73 de Rich
KI6RRQ


Message: 15
Date: Fri, 2 Oct 2009 23:26:38 -0700
From: "Jeff Yanko" <wb3jfs at cox.net>
Subject: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE
To: "Gary \"Joe\" Mayfield" <gary_mayfield at hotmail.com>,	"'Charles
	Suprin'" <hamaa1vs at gmail.com>

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>
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
> 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
>