Diplex Sky rf and UHF signal

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hazza87

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Topic # 89546 4-Sep-2011 21:44

I am doing some work upgrading a mates audio visual setup :

Lounge - Panasonic LCD TV (freeviewHD built in)
- My Sky Hdi

Bedroom - Small LCD (no freeview)

There is existing cabling in the walls 3 RG6 cables from the roof to main lounge (1 to sky dish, 1 to uhf aerial, 1 spare)
There is also an RG6 cable from the lounge to the bedroom and an ir extender to the bedroom from lounge.

So i would like to use the existing RG6 cable to send the sky to the bedroom, obviously i will need an rf modulator to convert the my sky composite to RF on RG6. Any recomendations? found a few at jaycar.

But i would also like to get freeviewHd in that bedroom.
Is there a way to diplex the UHF signal from the aerial with the modulated UHF channel from the Sky box and send them both down the cable to the bedroom? If so what do i need?

Thanks

cyril7

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Reply # 516641 5-Sep-2011 07:20

Hi, there are several ways to do that, but the first and simplest way, in the lounge connect the uhF antenna to the modulator input, then connect the UHF output to a splitter, wth one leg to the lounge TV and the other catching the 3rd spare cable to back to the roof space, then connect that to the feed going to the bedroom, you will now find what is on the UHF antenna and modulator. Depending on what signal levels are on the antenna feed will determine if any gain is needed, but if it were I would put it directly after the modulator and only if really needed, Kingray make a suitable two output distribution amp (looks like a bar of soap.

Make sure you put the modulator on a low channel like 22-25, reason is that with the FreeView|HD channle move coming up you will need the more commonly used Ch36 free.

Cyril

trig42

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Reply # 516662 5-Sep-2011 08:52

cyril7: Hi, there are several ways to do that, but the first and simplest way, in the lounge connect the uhF antenna to the modulator input, then connect the UHF output to a splitter, wth one leg to the lounge TV and the other catching the 3rd spare cable to back to the roof space, then connect that to the feed going to the bedroom, you will now find what is on the UHF antenna and modulator. Depending on what signal levels are on the antenna feed will determine if any gain is needed, but if it were I would put it directly after the modulator and only if really needed, Kingray make a suitable two output distribution amp (looks like a bar of soap.

Make sure you put the modulator on a low channel like 22-25, reason is that with the FreeView|HD channle move coming up you will need the more commonly used Ch36 free.

Cyril

Exactly how I would do it.

If you get the LM3879 from Jaycar, you will be able to do this. The LM3878 does not have the RF input.

You could call Sky and see if they can get a Modulator to you - the ones they provide have an RF input. I think Sky only charge $50 for a modulator whereas the Jaycar one is $90

Skolink

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Reply # 516692 5-Sep-2011 09:40

The cheapest way would be to use a video recorder (we gave ours away). Plug Sky (composite/Svideo) into the AV inputs and loop the FreeviewHD UHF signal through the video recorder RF in /out.
Set the video recorder to A/V input channel and put the remote away.
You will still need to split the UHF signal to both the loung TV and the video recorder of course.

richms

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Reply # 516768 5-Sep-2011 11:45

The low 20's in UHF are not free, they are assigned to portable walkietalkies in NZ, so you get bursts of noise on those channels.

I just use a backwards splitter to combine, and then into the distribution amp. An amp on the antennas before combining stops the modulated sources radiating out the antenna to the neighbours.

Richard rich.ms

hazza87

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Reply # 516784 5-Sep-2011 12:42

Thanks everybody
Would a LM3873 from jaycar also work, i see it needs a separate power supply but would still work out cheaper.
http://www.jaycar.co.nz/productView.asp?ID=LM3873&keywords=rf+modulator&form=KEYWORD

The aerial is a medium gain one with direct line of sight to Waitarua and signal quality and strength is 100% on all freeview channels so that shouldnt be an issue.

Also what UHF channel should i use for the modulator if not low 20's?? Doesnt look like the above one is very changeable, will this matter?

cyril7

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Reply # 516791 5-Sep-2011 13:08

If you find UHF CB is an issue then Ch24 or above should be fine, although as you are in Auckland the 36 is fine.

Cyril

hazza87

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Reply # 516793 5-Sep-2011 13:13

Also what should i do at the bedroom end? the single rg6 cable will contain both the rf modulated channel and the uhf signal.
Can i simply plug this into the freeview receiver then use the rf out from the receiver to the tv as well as composite for the freeview channels? Will the rf out from the receiver still keep the modulated sky channel? or even better can the freeview receiver tune the sky channel so i dont have to flick between tv and av1?

cyril7

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Reply # 516797 5-Sep-2011 13:23

Hi, I dont know of any FreeView|HD STBs that modulate the internal decode, so you will need to use a composite feed (or better) for FreeView and obviously the RF out of the STB will pass onto the TV for the Sky feed.

Cyril

richms

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Reply # 516826 5-Sep-2011 13:55

hazza87: Thanks everybody
Would a LM3873 from jaycar also work, i see it needs a separate power supply but would still work out cheaper.
http://www.jaycar.co.nz/productView.asp?ID=LM3873&keywords=rf+modulator&form=KEYWORD

That one is VHF, so you can use a standard diplexer to prevent backfeed. That will mean no VHF reception tho

I think that both the channels that modulator outputs on are in use in auckland. certainly a friend had no luck mixing a cheap VHF modulator in with the off air VHF, as it is low band and there is analog off skytower and waitartua on low band. which is a tiny piece of spectrum.

Richard rich.ms

hazza87

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Reply # 516832 5-Sep-2011 14:02

richms:
hazza87: Thanks everybody
Would a LM3873 from jaycar also work, i see it needs a separate power supply but would still work out cheaper.
http://www.jaycar.co.nz/productView.asp?ID=LM3873&keywords=rf+modulator&form=KEYWORD

That one is VHF, so you can use a standard diplexer to prevent backfeed. That will mean no VHF reception tho

I think that both the channels that modulator outputs on are in use in auckland. certainly a friend had no luck mixing a cheap VHF modulator in with the off air VHF, as it is low band and there is analog off skytower and waitartua on low band. which is a tiny piece of spectrum.

I am not using any VHF at all so that should not be an issue (no vhf aerial)
But will it carry the UHF signal as well as the modulated sky ---> vhf channel?

Sounds like it may be easier to get the $90 one.

Thanks cyril7 i had read somewhere that freeviewHD stb's do not output on the rf out, only passthrough.

hazza87

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Reply # 517026 5-Sep-2011 17:57

I have now purchased the $90 jaycar modulator (LM 3879) and a sommet freeviewHD box ($139 - farmers)
will go back over there and set it up and test it in the next few days.

While im on the topic i noticed an
F-Connector Tool Set at jaycar for half price ($49.99) i was considering getting one to crimp all the f connections on properly (currently using twist on f connectors). Is this one any good? will it do the PPC compresison connectors? any other recommendations?

cyril7

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Reply # 517089 5-Sep-2011 19:20

Hi, yes that tool should do the posted PPC connectors, just dont pay that price, its about 6x too much

Cyril

richms

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Reply # 517094 5-Sep-2011 19:34

Hit ebay up for a crimptool etc out of asia. Jaycar is only really viable for the "oh crap I need it now" purchases

Richard rich.ms

hazza87

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Reply # 517101 5-Sep-2011 19:55

Anywhere locally i can get one for a reasonable price then? i tried ideal electrical and they had one almost identical but just the crimp tool for $44.95
Or should i just get one of ebay and wait the week to get it?