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Re: Gettng on AO-40 - Uplink Antenna



Mike
My comments are imbedded within your questions.
Rick

----- Original Message -----
From: "Mike King - KM0T" <scsueepe@mtcnet.net>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, August 12, 2002 11:44 PM
Subject: [amsat-bb] Gettng on AO-40 - Uplink Antenna


Hi all, got some equipment for getting on AO-40.  Looking at a 435 Mhz
uplink antenna.  Hope to be on in a month or two.

Question, is the circular polarization uplink antenna such as a M2 436CP30
verses a single polarization unit a good way to go?
***That is a superb antenna----- Is it worth the cost---I doubt it
.My research has indicated that there is a 3 db difference to the sat, plus
possibly less
fading?
*** "Possibly"  is the correct term and closer to 2.4 db difference.
I guess how much better is it in terms of operation?
*** If you need the GAIN and don't have the power to make up for it -- then
definitely go for it

Also, I understand that the RHC polarization, just set the antenna up for
that, no need to change polarization?
*** TRUE
 I assume that the A040 antennas basically allways point back at earth in
 the same polarization.  I guess what Im asking is if there is any reason
or need for a polarization switch
***  No need for a polarization switch
to optimize the uplink signal.

In addition, any comments on this antenna verses the unit from Gulf Alpha
antennas.  That unit is about 3/4 the boom lenght of the 117" M2 unit.  Any
users out there with comparisons?
***  Never tried Gulf Alpha, but you can take the M2 specifications to the
bank, i.e., they are accurate
       and true.

I will be using a FT-847 with 50 watts out (or less) to one of these
antennas.  Question is that without offending LELIA (I think thats the name
anyway) will 50 watts do the job (assuming reasonable feedline loss of 1 to
1.5 db) or will a brick still be required?  I really dont have a feel for
this as all the reading I have done kind of shows guys using different power
levels across the board.  Also I imagine this has some to do with single
verses circular polarization as well.
***  I only work L-band uplink so I can't help you on this one

So, sorry if this has all been covered before (I would imagine it has) and I
appreciate any info from the veterens on the bird.  Any tips appreciated,
dont want to be a lid.

73 and thank you.
*** Good luck --  hope to see you on the bird
73
Rick

Mike - KM0T en13vc - NW Iowa
www.qsl.net/km0t



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