TV/Sat splitter combiner questions

[Huevos]

On the roof there is a TV/Sat splitter. At the the bottom there is a 3 terminal combiner wall socket. If everything below 900MHz is siphoned through to the TV aerial how do the 22kHz tone, diseqc commands and LNB power get up to the satellite dish? Also what stops the TV aerial being fed DC and causing an LNB short.

Regarding the 3 way socket what is the difference between an intermediate socket and an end of run socket?

[Robbo]

The TV/uhf side should have no DC pass, the satellite side needs DC pass to power the LNB.

one would imagine that the sat side contains a low-pass filter and a band pass filter to let the DC, 22khz and the sat IF through, with the UHF side just a bandpass filter.

I'm sure there will be a block diagram/schematic of a diplexer or the net somewhere.

[PaulR]

I'm a bit suspicious of the splitter being used as a combiner. A proper combiner will do exactly as Robbo says with DC paths and frequency bands correctly implemented. The diagram on the photo looks for all the world as if it's a simple resistive splitter/combiner and the only reason it hasn't shorted out is because the terrestrial aerial doesn't have a DC path through!

I dont understand what you mean by "Regarding the 3 way socket what is the difference between an intermediate socket and an end of run socket?" This is a term I would normally think of for the old co-axial cable connected ethernet sockets.

[Huevos]

one would imagine that the sat side contains a low-pass filter and a band pass filter to let the DC, 22khz and the sat IF through, with the UHF side just a bandpass filter.

I was guessing bandpass for sat and bandstop for TV. It's advertised to pass diseqc commands and that it can be used up as a combiner and down as a splitter. I was just hoping someone knew the product.

I dont understand what you mean by "Regarding the 3 way socket what is the difference between an intermediate socket and an end of run socket?" This is a term I would normally think of for the old co-axial cable connected ethernet sockets.

Well most 3 way sockets here are labled that way. Intermediate means you loop the cable from the aerial downlead into the first socket and out again to subsequent sockets in the run... instead of using TV aerial splitters. Obviously this can't work for satellite as we know it but maybe this type of socket is used in Spanish installs as the majority of satellite installs here are solely vertical lo-band. Not sure about the end of run type but that is supposed to replace a splitter. To me they look pretty much the same as the 3 way sockets sold in the UK (for example Labgear PSW132) so I was hoping someone who has used one of those sockets there could comment.

[PaulR]

The Labgear PSW132 is a triplexer, which I have used myself here at home. It takes a single cable of combined signals and splits them off so that the sat connection passes DC-30KHz up (to the LNB) and 950-2400MHz down to the satellite receiver. The FM/DAB socket strips out 87.5-230 MHz and the TV socket supplies 470-862 MHz. This means that DC to 2400MHz

This is fed from a multiswitch in my case which, effectively, combines the satellite, TV and radio frequencies together so that 87.5 - 2400MHz travels down a single cable and DC to 30Khz travels up. I don't understand where this looping in and out fits in.

It sounds, from what you're saying, like the Spanish just run a cable around a building and tap into it (just ethernet used to) wherever they want. It's not smething I've come across before but there ae several installers here who may have. Hope they can help on this.

[deleted]

i have only ever used the triplexer on multiswitch distribution

[Channel Hopper]

It sounds, from what you're saying, like the Spanish just run a cable around a building and tap into it (just ethernet used to) wherever they want.

It is not just in Spain, many central European installers do the same. The idea of tapping off a percentage of signal works up to a point, usually a frequency limit of about 500/550 MHz, which is why many cable companies can fit a loop system into buildings without a problem..

Often the signal levels per point can vary by as much as a factor of ten, but the robustness of the tuner AGC will keep things in check.

[pipino]

hi huevos ,
i know the stuff you are dealing with ..simply you cant use intermediate socket in the middle on these set ups because will only alow voltage for sat and let thru passivaly terrestrial and any socket in the middle may provoc a short circuit on the sat receiver..those are tipical instalations when you cant have a second cable run ..aslo those have another name (multiplexor/demultiplaxor)...if you have trouble with an instalation just tel me what are you planning to do ,i may help me if any doute...best regards