Setup:
Pansat 3500sd
T90
LNBFs:
3 x M20R
3 x ExtremeII
1 x Invacom QPH-031
Southwest US
With a new Wave Frontier T90 on the ground with a great southern view for initial alignment, a novel temporary mount was constructed to provide a highly stable mount while swinging the antenna around and easy/rapid fine adjustment to plumb the tripod.
First, an attempt to receive G10R was made connected to the linear ports of a Invacom LNBF. Performance was disappointing, with the strongest transponder (T6) peaking at only 30% while blind scanning the entire satellite. The Equity Broadcasting channels at Tp 1 and 5 have yet to be received at all. I manage to occasionally find Tp1, peaks at only 20% after a blind scan but no channels are ever found on a transponder scan. The two Fort Smiths on Tp21 can be received OK.
Next, T5 was a success with the linear feed at the centre bar (0), with the strongest peaks at about 90%. A neighbor with a 76cm winegard can reach 99% peaks on the stronger transponders, leading me to wonder how these T90s stack up against standard parabolic Ku dishes in general.
The beacons on a DSS satellite was then used find a peak with a LNBF at dead centre (0) of the LNB bar. This was a great success, with most signals found in the 90% range if not a full 99%-100%. A second DSS was peaked with an LNBF placed at around 15 on the bar. These first two LNBFs were easy to align and peak, presumably because of the circular polarization of a DSS signal. For a third try, T5 was selected and could never be found with the linear LNBF set at around 15 on the LNBF bar.
The linear LNBF was next returned to dead centre (0) on the bar and the T5 signal was re-acquired. In this configuration the LNBF was slowly stepped across the bar to it's intended resting place, re-peaking the signal by re-aligning the antenna as it went. As the LNBF was moved away from centre, the signal peak obtainable decreased until it nearly disappears entirely at about the 10-mark on the LNB bar.
It seems that skew is very important with linear feeds but a peak in the signal with both the antenna and LNBF skew adjustment does not seem to bring a noticable improvement in signal quality.
Questions:
1. Is it normal to experience a degraded signal at the edges of the bar in this manner?
2. The LNB bar is to be mounted to match the concavity of the secondary reflector (i.e. concave outward), right?
3. I'm getting horrible performance with the Extreme IIs, by far the worst of any feed tried so far. Has anyone had success with this feed?
Thanks in advance for any comments.
B
Pansat 3500sd
T90
LNBFs:
3 x M20R
3 x ExtremeII
1 x Invacom QPH-031
Southwest US
With a new Wave Frontier T90 on the ground with a great southern view for initial alignment, a novel temporary mount was constructed to provide a highly stable mount while swinging the antenna around and easy/rapid fine adjustment to plumb the tripod.
First, an attempt to receive G10R was made connected to the linear ports of a Invacom LNBF. Performance was disappointing, with the strongest transponder (T6) peaking at only 30% while blind scanning the entire satellite. The Equity Broadcasting channels at Tp 1 and 5 have yet to be received at all. I manage to occasionally find Tp1, peaks at only 20% after a blind scan but no channels are ever found on a transponder scan. The two Fort Smiths on Tp21 can be received OK.
Next, T5 was a success with the linear feed at the centre bar (0), with the strongest peaks at about 90%. A neighbor with a 76cm winegard can reach 99% peaks on the stronger transponders, leading me to wonder how these T90s stack up against standard parabolic Ku dishes in general.
The beacons on a DSS satellite was then used find a peak with a LNBF at dead centre (0) of the LNB bar. This was a great success, with most signals found in the 90% range if not a full 99%-100%. A second DSS was peaked with an LNBF placed at around 15 on the bar. These first two LNBFs were easy to align and peak, presumably because of the circular polarization of a DSS signal. For a third try, T5 was selected and could never be found with the linear LNBF set at around 15 on the LNBF bar.
The linear LNBF was next returned to dead centre (0) on the bar and the T5 signal was re-acquired. In this configuration the LNBF was slowly stepped across the bar to it's intended resting place, re-peaking the signal by re-aligning the antenna as it went. As the LNBF was moved away from centre, the signal peak obtainable decreased until it nearly disappears entirely at about the 10-mark on the LNB bar.
It seems that skew is very important with linear feeds but a peak in the signal with both the antenna and LNBF skew adjustment does not seem to bring a noticable improvement in signal quality.
Questions:
1. Is it normal to experience a degraded signal at the edges of the bar in this manner?
2. The LNB bar is to be mounted to match the concavity of the secondary reflector (i.e. concave outward), right?
3. I'm getting horrible performance with the Extreme IIs, by far the worst of any feed tried so far. Has anyone had success with this feed?
Thanks in advance for any comments.
B
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