[amsat-bb] You learn something new every day...

[N0JY]

Hello AO-51 V/S gang!

I've been on the past couple of nights trying out my modified K5GNA BBQ 
dish, I had removed the dipole and replaced it with a LHCP patch feed I 
built.  Past mode */S runs on AO-51 were spent getting the feed back in 
the focus.  The passes this week though still left me with some bad 
fades and signals varying from S9+ to nothing but noise.

Well I finally figured it out during the 00:00 pass tonight... I'm using 
SATPC32 rotor control and I was fiddling with the pointing corrections.  
Tonight was an overhead pass, so the signals should have been great.  
They weren't though, so I started tweaking the rotor degree 
corrections.  Came to find that a +14 degree azimuth gave me the great 
signals I expected to hear!  So I got to thinking about it.

I know the rotator/antenna assembly is pointed right, north is north and 
east is east and such.  All of the other antennas give me the kind of 
signals I expect, when pointing toward a particular satellite and some 
local beacons and sweeping around them.  So it must be one of two 
things:  either the patch feed is off center, and I'll admit that it was 
heck to line up exactly using the PVC arrangement that I have created to 
get the AIDC downconverter pointed back toward the dish.  I looks pretty 
centered... but, could it be off just a tad to the side so that I am 
actually feeding off-center, hence the need for a 15 degree adjustment 
to get the best signal?  The other thought, the dish is mounted with the 
left edge about 1 foot to the right of the 70cm  40el crossed yagi, 
could the yagi be influencing the signal causing the apparent bend in 
the pointing?  And probably vice versa, if so.

Your thoughts on this would be appreciated.  Meantime, I have at least a 
workaround to get the solid downlink that I was looking for.  No 
polarization fades with the CP patch, and the 15 degrees offpoint isn't 
going to affect the 2m uplink as the bandwidth of that antenna (20el 
crossed) doesn't seem to mind.  So, hopefully you won't have to hear me 
sign because I lost the downlink anymore this week!

73 and thanks,
Jerry
N0JY