My Humax Forum » Freesat HD » FOXSAT HDR

One cable, without loop through link?

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    AlanFoxsat

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    grahamlthompson - 4 hours ago  » 

    AlanFoxsat - 1 min ago  » 
    Ah I see now. The cable splitter does not have DC pass through that is needed for the lnb to work and presumably those that have it, only allow it in the one direction to prevent conflicting DC power. Not sure if your post was truncated or DOW means something but I get the idea. Thanks.

    Should have said down to tuner 1.
    You need a splitter that passes DC from the tuner 2 cable and not the TV.
    https://www.amazon.co.uk/Way-TV-Satellite-Combiner-Splitter/dp/B06Y3MR4CC/ref=sr_1_13?dchild=1&keywords=satellite+splitter&qid=1593529600&sr=8-13
    Current pass direction isn't shown
    Connect tuner 1 out to in/out. Connect TV to TV and Sat to tuner 2 in. a Test meter with a battery should be able to confirm the splitter blocks DC positive in the direction you need.
    You might have to build your own DC blocker. A silicon diode soldered into the coax core the right way round should do this basically you need to block DC out from the TV tuner getting to the splitter.

    The link has two options. The combiner appears to be for combining/splitting satellite and aerial RF but the splitter option has arrows showing DC pass on both OUT ports with arrows which would seem to show that power can only pass in the direction indicated?

    | Tue 30 Jun 2020 19:51:00 #11 |
  2. grahamlthompson

    grahamlthompson

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    AlanFoxsat - 13 mins ago  » 

    grahamlthompson - 4 hours ago  » 

    AlanFoxsat - 1 min ago  » 
    Ah I see now. The cable splitter does not have DC pass through that is needed for the lnb to work and presumably those that have it, only allow it in the one direction to prevent conflicting DC power. Not sure if your post was truncated or DOW means something but I get the idea. Thanks.

    Should have said down to tuner 1.
    You need a splitter that passes DC from the tuner 2 cable and not the TV.
    https://www.amazon.co.uk/Way-TV-Satellite-Combiner-Splitter/dp/B06Y3MR4CC/ref=sr_1_13?dchild=1&keywords=satellite+splitter&qid=1593529600&sr=8-13
    Current pass direction isn't shown
    Connect tuner 1 out to in/out. Connect TV to TV and Sat to tuner 2 in. a Test meter with a battery should be able to confirm the splitter blocks DC positive in the direction you need.
    You might have to build your own DC blocker. A silicon diode soldered into the coax core the right way round should do this basically you need to block DC out from the TV tuner getting to the splitter.

    The link has two options. The combiner appears to be for combining/splitting satellite and aerial RF but the splitter option has arrows showing DC pass on both OUT ports with arrows which would seem to show that power can only pass in the direction indicated?

    Which is why you may need to make an external DC blocking add on by adding a silicon diode,

    You need a unique solution.

    A reverse biased silicon diode stops any current passing. A bridge connection converts AC to DC.

    https://www.instructables.com/id/Make-A-Bridge-Rectifier-From-Diodes/

    A single one blocks all DC current in one direction. That's what you need for the Tv Connection/

    | Tue 30 Jun 2020 20:15:22 #12 |
  3. Trev

    Trev

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    A straight forward diode in the signal path, (unless bypassed with a capacitor) will not pass signal level AC unless it is forward biased on by approx 0.6V between anode and cathode. Surely his rather defeats the objective. You Need the signal level AC through but block the DC from the unwanted source.

    A combination of the splitter and a diode to block DC in the opposite direction will block both signals and DC current both ways.

    | Wed 1 Jul 2020 9:40:10 #13 |
  4. grahamlthompson

    grahamlthompson

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    Trev - 4 hours ago  » 
    A straight forward diode in the signal path, (unless bypassed with a capacitor) will not pass signal level AC unless it is forward biased on by approx 0.6V between anode and cathode. Surely his rather defeats the objective. You Need the signal level AC through but block the DC from the unwanted source.
    A combination of the splitter and a diode to block DC in the opposite direction will block both signals and DC current both ways.

    An isolated wall outlet plate in the lead to the TV will block DC and pass the rf.

    https://www.toolstation.com/axiom-tv-socket/p65086

    | Wed 1 Jul 2020 13:45:41 #14 |
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    AlanFoxsat

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    I have seen several references that these splitters do indeed have diodes to protect the DC going the wrong way. Looking at the reviews, lots of people seem to be using them and I have not seen any reports of damaged equipment. (just the expected complaints from people who don't understand the channel limitation)

    Based on this, is their any benefit of using the splitter (as suggested) connected to lnb1 out, rather than before the humax. i.e. one output to the humax (still using the link through cable), the other to the tv ? It would appear this is the way most people are doing it, connecting to two devices that don't have an out socket?

    Incidentally, just to check, whilst I don't have a splitter, If I just connect the tv to lnb1 out, accepting that some offered channels will not work, there is no danger of damage from this? Also, I seem to remember that a single scheduled recording could not be guaranteed to use either of the tuners so could potentially fail?

    | Wed 1 Jul 2020 14:20:29 #15 |
  6. grahamlthompson

    grahamlthompson

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    AlanFoxsat - 8 mins ago  » 
    I have seen several references that these splitters do indeed have diodes to protect the DC going the wrong way. Looking at the reviews, lots of people seem to be using them and I have not seen any reports of damaged equipment. (just the expected complaints from people who don't understand the channel limitation)
    Based on this, is their any benefit of using the splitter (as suggested) connected to lnb1 out, rather than before the humax. i.e. one output to the humax (still using the link through cable), the other to the tv ? It would appear this is the way most people are doing it, connecting to two devices that don't have an out socket?
    Incidentally, just to check, whilst I don't have a splitter, If I just connect the tv to lnb1 out, accepting that some offered channels will not work, there is no danger of damage from this? Also, I seem to remember that a single scheduled recording could not be guaranteed to use either of the tuners so could potentially fail?

    That's how my TV is connected. Works as described. However my Foxsat is setup as two cables (same). No diseqc in use. So continues to work as twin tuner recorded with the only restriction of max two recordings at the same time. I also have a HDR-1000s connected to the same quad lnb.

    | Wed 1 Jul 2020 14:33:27 #16 |
  7. Trev

    Trev

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    grahamlthompson - 1 hour ago  » An isolated wall outlet plate in the lead to the TV will block DC and pass the rf.
    https://www.toolstation.com/axiom-tv-socket/p65086

    Yes, of course it will, but it won't have a diode in series, it will have a capacitor.

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    | Wed 1 Jul 2020 15:11:58 #17 |
  8. grahamlthompson

    grahamlthompson

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    Trev - 27 secs ago  » 

    grahamlthompson - 1 hour ago  » An isolated wall outlet plate in the lead to the TV will block DC and pass the rf.
    https://www.toolstation.com/axiom-tv-socket/p65086

    Yes, of course it will, but it won't have a diode in series, it will have a capacitor.

    I know. The capacitor will block DC and the impedance will be tiny at SAT IF frequencies. just what is needed. Tuner 2 on the Humax will need to retain lnb control. This should allow the box to work normally when the Foxsat is in full sby.

    | Wed 1 Jul 2020 15:13:44 #18 |
  9. Trev

    Trev

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    So what you are saying now is that the OP needs a capacitor to block the DC? I'll go along with that.

    | Wed 1 Jul 2020 15:23:20 #19 |

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