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DISH SETUP: Single sat, Multi-Sat & Motorised
Invacom 0.3dB vs. Octagon PLL vs. SMW PLL Ku LNBs
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<blockquote data-quote="s-band" data-source="post: 981544" data-attributes="member: 407744"><p>More comparisons. I decided to check the noise figure of several LNAs and LNBs. Measurements were done comparing the noise from a “hot” source (a piece of microwave absorber) with noise from the quietest bit of sky I could find. Hot noise minus cold noise (sky) gives the Y factor. From that noise figure & noise temperature can be calculated. There’s a good summary here: <a href="https://gm8bjf.joomla.com/images/pdf/noise_figure.pdf" target="_blank">https://gm8bjf.joomla.com/images/pdf/noise_figure.pdf</a></p><p></p><p>It’s quite hard to eliminate the possibility of ground noise sneaking in on the side lobes of the feeds especially as the garden is surrounded by trees. That will tend to make the devices seem worse than they really are. I didn’t have time or enthusiasm to check on more than one frequency. All will vary across the bands. Most tests were done at an IF of 1.2GHz. In the case of the LNAs at 3.9GHz for the Dexcel and 10.95GHz for the SMW. The figures below are as measured and calculated, there's a fair probability of errors but I think they give a reasonable idea of reality.</p><p></p><p>[ATTACH=full]96350[/ATTACH]</p><p></p><p>Observations:</p><p>Norsat - probably meets its spec as it is easy to pick up another 20 deg K on side lobes.</p><p>Dexcel - Not far off its 120K, can be forgiven as it is 33 years old.</p><p>TIT C1W PLL - Hmm, 15K vs 82K. Not much difference between V & H. Even assuming some side lobe pick up it’s much worse than the Norsat.</p><p>HDSKY - Unknown history, came with the 1.8m CM. Good enough for Sky, I guess.</p><p>Octagon OTLSO - Hmm again, 0.1dB vs 1dB not much to say except there wasn’t a measurable difference between the C120 modified one and an unmodified unit.</p><p>SMW 1dB Max - Meets spec</p><p>Unknown Ka - I guess 2dB+ is to be expected from a surplus 5yr old Ka.</p></blockquote><p></p>
[QUOTE="s-band, post: 981544, member: 407744"] More comparisons. I decided to check the noise figure of several LNAs and LNBs. Measurements were done comparing the noise from a “hot” source (a piece of microwave absorber) with noise from the quietest bit of sky I could find. Hot noise minus cold noise (sky) gives the Y factor. From that noise figure & noise temperature can be calculated. There’s a good summary here: [URL]https://gm8bjf.joomla.com/images/pdf/noise_figure.pdf[/URL] It’s quite hard to eliminate the possibility of ground noise sneaking in on the side lobes of the feeds especially as the garden is surrounded by trees. That will tend to make the devices seem worse than they really are. I didn’t have time or enthusiasm to check on more than one frequency. All will vary across the bands. Most tests were done at an IF of 1.2GHz. In the case of the LNAs at 3.9GHz for the Dexcel and 10.95GHz for the SMW. The figures below are as measured and calculated, there's a fair probability of errors but I think they give a reasonable idea of reality. [ATTACH=full]96350[/ATTACH] Observations: Norsat - probably meets its spec as it is easy to pick up another 20 deg K on side lobes. Dexcel - Not far off its 120K, can be forgiven as it is 33 years old. TIT C1W PLL - Hmm, 15K vs 82K. Not much difference between V & H. Even assuming some side lobe pick up it’s much worse than the Norsat. HDSKY - Unknown history, came with the 1.8m CM. Good enough for Sky, I guess. Octagon OTLSO - Hmm again, 0.1dB vs 1dB not much to say except there wasn’t a measurable difference between the C120 modified one and an unmodified unit. SMW 1dB Max - Meets spec Unknown Ka - I guess 2dB+ is to be expected from a surplus 5yr old Ka. [/QUOTE]
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DISH SETUP: Single sat, Multi-Sat & Motorised
Invacom 0.3dB vs. Octagon PLL vs. SMW PLL Ku LNBs
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