[amsat-bb] Re: AMSAT-BB Digest, Vol 2, Issue 135

[Gary McKelvie]

Hi to John and the List,

I'm certainly taking onboard what people are suggesting :)

I think I also have said that I have  a crossed 70 cm 19 element Yagi 
from before, as well as rotators to enable both azimuth and elevation 
control of the antennas so i'm starting to think even with the fixed 
polarization of the 9/19 element Tonna i will need to use the 
elevation rotator.

Now to my next though If I have this right the LEO's use 70cm as the 
down link and the 2m side as the uplink, so to my way of thinking I 
need the most gain really on the down link side.

So would it be better to have a small 2m Yagi crossed about 4-5 
elements. The 847 output on 2 and 70 is variable 5 - 50 watts on both 
bands all modes.
If I was to go this way I would also look at circular polarization on 
the antennas. I would also be looking at using a duplexer to enable 
me to use one feed line which again would make the XYL happier as 
where the antennas will have to go when up is across the back lawn. I 
understand that will impact on the performance of the system but I 
willing to accept that :)
So the question is RHCP or LHCP? Which is best or do I need to be 
able to switch from one to another?

As you can see  I don't have a fixed idea on the station as yet. I 
find it easier to talk it through with people first then go get it up 
and running :)
So thank you all for listening to me and the help as well.

73 Gary

At 01:45 23/02/2007, John Kopala wrote
:
>The beams with their inherent gain will enable working satellites on more
>passes and lower elevations.  You may experience some fading with fixed
>polarization, but the gain of the antennas may compensate for that.  Some of
>the satellites do require a little more power to get into, but your setup
>should be more than adequate.

Gary McKelvie
G7USC
Web : www.garym.org.uk
Mobile : +447968501863
MSN Messenger : gm7usc at hotmail.com
So Long and Thanks for all the Fish