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DISH SETUP: Single sat, Multi-Sat & Motorised
Motorised dish not moving with lnb plugged in
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<blockquote data-quote="Terryl" data-source="post: 1065231" data-attributes="member: 369937"><p>Sorry but I don't have a schematic for an 8 port LNB handy, and yes this has been tested in my lab on a 4 port output LNB at work back a long time ago.</p><p></p><p>Trust1, the test you did was with only one receiver attached, (your Maxplus 2100) and coupled out somehow to multiple ports on the LNB, try this with 8 different receivers attached, and the LNB in an active mode actually receiving a satellite signal, and the different receivers on different channels and different polarity transponders.</p><p></p><p>Also we used specially modified receiver's to monitor the LNB's current draw, these receivers were modified to allow the active RF circuit to be monitored without affecting the signal to/from the LNB, attaching an amp meter inline would cause the RF circuit to not work as designed.</p><p></p><p>The closest thing I can find for a schematic would be this application guide for a matrix switching IC,(link to a PDF at the bottom of this post) it is a very simple one, look at pages 6 and 13, on page 6 at the bottom it shows the DC current draw with one active LO output port, and all 4 active, as you can see the DC current draw goes up when more ports are active, on page 13 is the simplified schematic showing the DC power inputs from the attached receivers. </p><p></p><p>It shows 4 DC voltage regulators, one on each receiver port, this is not common to most consumer grade LNB's as the cost would be too high, but after the regulators it shows each feeding into a diode, in a perfect world with perfect parts the regulators would put out exactly the same DC voltage, and then all 4 would be feeding the power. </p><p></p><p>But there are very few DC regulators that would feed the exact same DC voltage, so with diode's seeing a slightly different DC voltage on the input only the one seeing the highest voltage would feed the circuit, and again there are no perfect diodes, and seeing that the power supplys are a very simple design they can't be directly attached together into one feed, one or more would get quite hot.</p><p></p><p>I will admit that not all LNB's are the same internal design and use the same type of circuitry, I have seen many many different designs and configurations over the years.</p><p></p><p>If you want to monitor the DC current and voltage out to an active LNB the best way would to take a look for the internal DC power circuit for the LNB connection on the receiver, look for the DC power feed from the receivers main power supply to this circuit, it is there you would do the DC current and voltage measurements (with proper calibration) for the attached LNB with special circuitry as to not affect the RF path to the receivers tuner.</p><p></p><p>[code]https://www.nxp.com/docs/en/application-note/AN11674.pdf[/code]</p><p></p><p></p><p>Opps sorry too much coffee this morning again, I'm rambling on again....My fault.</p></blockquote><p></p>
[QUOTE="Terryl, post: 1065231, member: 369937"] Sorry but I don't have a schematic for an 8 port LNB handy, and yes this has been tested in my lab on a 4 port output LNB at work back a long time ago. Trust1, the test you did was with only one receiver attached, (your Maxplus 2100) and coupled out somehow to multiple ports on the LNB, try this with 8 different receivers attached, and the LNB in an active mode actually receiving a satellite signal, and the different receivers on different channels and different polarity transponders. Also we used specially modified receiver's to monitor the LNB's current draw, these receivers were modified to allow the active RF circuit to be monitored without affecting the signal to/from the LNB, attaching an amp meter inline would cause the RF circuit to not work as designed. The closest thing I can find for a schematic would be this application guide for a matrix switching IC,(link to a PDF at the bottom of this post) it is a very simple one, look at pages 6 and 13, on page 6 at the bottom it shows the DC current draw with one active LO output port, and all 4 active, as you can see the DC current draw goes up when more ports are active, on page 13 is the simplified schematic showing the DC power inputs from the attached receivers. It shows 4 DC voltage regulators, one on each receiver port, this is not common to most consumer grade LNB's as the cost would be too high, but after the regulators it shows each feeding into a diode, in a perfect world with perfect parts the regulators would put out exactly the same DC voltage, and then all 4 would be feeding the power. But there are very few DC regulators that would feed the exact same DC voltage, so with diode's seeing a slightly different DC voltage on the input only the one seeing the highest voltage would feed the circuit, and again there are no perfect diodes, and seeing that the power supplys are a very simple design they can't be directly attached together into one feed, one or more would get quite hot. I will admit that not all LNB's are the same internal design and use the same type of circuitry, I have seen many many different designs and configurations over the years. If you want to monitor the DC current and voltage out to an active LNB the best way would to take a look for the internal DC power circuit for the LNB connection on the receiver, look for the DC power feed from the receivers main power supply to this circuit, it is there you would do the DC current and voltage measurements (with proper calibration) for the attached LNB with special circuitry as to not affect the RF path to the receivers tuner. [code]https://www.nxp.com/docs/en/application-note/AN11674.pdf[/code] Opps sorry too much coffee this morning again, I'm rambling on again....My fault. [/QUOTE]
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DISH SETUP: Single sat, Multi-Sat & Motorised
Motorised dish not moving with lnb plugged in
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