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
Hi Jerry, N0JY
The only way to eliminate all of your uncertainty is to point the dish to the Sun and try to receive the Sun-Noise.
If the pick of Sun-Noise match both with the traking program of the Sun and the indication of the AZ and EL of your control box then you are calibrated otherwise you must apply the necessary corrections.
73" de
i8CVS Domenico
----- Original Message ----- From: "N0JY" n0jy@lavabit.com To: amsat-bb@amsat.org Sent: Thursday, August 20, 2009 2:51 AM Subject: [amsat-bb] You learn something new every day...
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
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