TV/Sat/FM Triplexers - noticeable negative impact on signal?

[c128]

Due to limited conduit space to my lounge TV-point, I'm thinking of using a combiner/triplexer in order that I can have a single cable in the wall to combine my Satellite, FM and TV connections.

So...in the loft I'm thinking of one of these:

http://www.tvaerials.com/product.aspx?productid=372

...and in the lounge one of these:

http://www.reallycleverhomes.co.uk/acatalog/MK_K5853_WHI_TV_FM_satellite_triplexer_module.html

Now...currently I have TV and Satellite via dedicated cables. In a real world situation, using CT100 through-out, am I likely to see much signal loss compared to dedicated cables if using a combiner/triplexer for all three of TV, Satellite and FM?

 

[RF Lighting]

I occasionally have problems with my sky picture going funny since I triplexed the downlead.

I will be eventually installing an extra cable and removing the triplexer.


If you have good signals on the sky and ariel then you might be ok

 

[c128]

Oh dear, that doesn't sound too promising...

Basically I need to ensure at least "good" DVB-T and DVB-S signals as, respectively, they will be feeding two twin tuner DVB-T PVRs and a single tuner DVB-S PVR. This I manage averagely at the moment on the DVB-T side with my current dodgy terrestrial aerial and decaying 80's dedicated downlead, and very well on the DVB-S side with a recently installed minidish and CT100 dedicated downlead (FM I'm not so worried about). So...I guess I was hoping to do better on the DVB-T side with a decent terrestrial aerial and CT100 through-out, albeit as a triplexed single cable combination of TV, Sat and FM at the point where all connections need to come down the wall and into the lounge.

Shame I didn't think about this much more when chasing the wall and only putting in a single conduit a few years ago... What I'm aiming for in the conduit in the end is two, separate, Cat5e cables (one for "proper" networking, and one to carry video elsewhere in the house) along with the TV, Satellite and FM connections. So - with a triplexed solution I'd have the two, slim, ethernet cables and one coax. Three coax cables would definitely be too tight with the ethernet cables, but I'm wondering whether two ethernet + two coax would fit and, if so, which of TV, Sat or FM would be best to combine/split?

 

[Sureitsoff?]

Oh dear, that doesn't sound too promising...

Basically I need to ensure at least "good" DVB-T and DVB-S signals as, respectively, they will be feeding two twin tuner DVB-T PVRs and a single tuner DVB-S PVR. This I manage averagely at the moment on the DVB-T side with my current dodgy terrestrial aerial and decaying 80's dedicated downlead, and very well on the DVB-S side with a recently installed minidish and CT100 dedicated downlead (FM I'm not so worried about). So...I guess I was hoping to do better on the DVB-T side with a decent terrestrial aerial and CT100 through-out, albeit as a triplexed single cable combination of TV, Sat and FM at the point where all connections need to come down the wall and into the lounge.

Shame I didn't think about this much more when chasing the wall and only putting in a single conduit a few years ago... What I'm aiming for in the conduit in the end is two, separate, Cat5e cables (one for "proper" networking, and one to carry video elsewhere in the house) along with the TV, Satellite and FM connections. So - with a triplexed solution I'd have the two, slim, ethernet cables and one coax. Three coax cables would definitely be too tight with the ethernet cables, but I'm wondering whether two ethernet + two coax would fit and, if so, which of TV, Sat or FM would be best to combine/split?

how big is the conduit that you have? if you carefully lay the cables into a sort of circular shape and tape into place you might get more cables in than just pulling in cables individually.

if you can get two ct1oo and two cat5 cables in the conduit, use one coax for sat and the other for an amplified signal from the aerial and then split the amplified signal to the respective tvs and recorders
also bear in mind that you might need a return from the sat rf2 output back up the conduit

 

[c128]

how big is the conduit that you have? if you carefully lay the cables into a sort of circular shape and tape into place you might get more cables in than just pulling in cables individually.

The internal diameter of the conduit is 17mm. At the moment I have 3 coax cables (TV, FM and Sat) and one ethernet cable stuffed down there. That was "a bit of an effort" - much swearing, push/pulling and washing-up liquid involved in getting that to happen (umm...sounds slightly dodgy now I write it ).

If you can get two ct1oo and two cat5 cables in the conduit, use one coax for sat and the other for an amplified signal from the aerial and then split the amplified signal to the respective tvs and recorders

Thanks - I'm thinking that might be the best way, and should at least be a bit easier to get down than what's down there at the moment. What I might actually use, I've decided, is MK's K5854-DAB from here (I already have an MK four-gang double modular faceplate for the current connections):

http://www.electrika.com/products/m/man-0290/pdfcat/mk-06-107.pdf

I've confirmed the connections with MK, and what this gives is a TV/FM-DAB/Satellite triplexer and a standalone F-connector in a small package. So if I connect with two coax cables to this, it will give me flexibility in the loft to decide which of DVB-T and DVB-S is standalone on that additional connector (even if the legends are then incorrect on the plate).

also bear in mind that you might need a return from the sat rf2 output back up the conduit

I'm going to skip this bit as what I've actually got in my lounge is a home theatre PC with DVB-T and DVB-S tuners, and I'm going to be feeding the output of that via the additional ethernet connection I'm adding - probably with one of those "s-video over cat5" devices, or something similar.

 

[c128]

An additional question relating to all of this...

Is there a coax, with the same/better characteristics than the usual CT100 spec, but that's thinner in diameter to make it easier for me in the conduit? Cost isn't much of an issue as there will only be about 4m X2 of it to cover the wall height and to an apppropriate place in my loft...

For example, would something like this be appropriate, as it would save >1mm over two typical CT100-spec cables?

http://www.maplin.co.uk/module.aspx?ModuleNo=34993&doy=28m9

 

[Sureitsoff?]

have a look at the satcure site cable section here http://www.satcure.com/accs/page8.htm and look for CT63 twin or shotgun cable as it is only 4mm in diameter

 

[c128]

Excellent - thanks, didn't know that existed. So...it seems to be greater loss, but only really over extended distances.

I'm tempted to give this a go and, if I suffer issues, I should be able to pull it back up quite easily and then maybe try one of its pairs + some ordinary CT100 for the triplexer. If that doesn't work, then two bits of CT100, but some good options there...

 

[Sureitsoff?]

using the cross sectional area of your conduit and assuming WT63 is 5mm in diameter to allow a bit of leeway you might/should get 10 cables down the conduit (but dont quote me!!!!!!!!!)

 

[electronicsuk]

How about running CT100 up to the point where the cables drop down the wall? Then you can joint to a smaller diameter cable, if things don't work out then you can joint and extend using CT100. Just fit a couper or male/female connectors under the floorboards.

 

[plugwash]

I'd imagine the losses of the joint would outweigh the reduction in losses from using slightly higher grade cable.

 

[electronicsuk]

Depends on the distance we're talking. At the sort of frequencies used for TV signals I wouldn't expect more than 1dB loss at the joint, whereas a long length of thin/lossy cable could easily introduce ten times that.

 

[Sureitsoff?]

as the poster has already stated that the cable length is approx 4m i dont think losses due to length are worth considering

 

[c128]

Well...this is my current thinking .

I've decided I'm going to fit a dual LNB in place of my single (just to complicate things a bit more), so that gives me one 17mm internal diameter conduit and the following required connections :

2 x Satellite connections
2 x Cat5 cables
1 x TV
1 x FM

The cable-run distance from satellite dish to wall socket is, I would guess, about 10m. So...I'm thinking 10m of CT63, of which one of the pair I'll run straight from the LNB down the conduit to the dedicated F-connector in the wall socket (details above), and the other side of the pair will stay "loft-side" to go into a triplexer. Also going into the triplexer in the loft will be my TV aerial and FM aerial, and the output from the triplexer I'll take via a single short run of CT100 to the TV/Sat/FM triplexer in the wall socket. In the conduit this will give me:

1 x CT100 (combined TV/FM/Sat)
1 x one side of CT63 (Sat)
2 x ethernet

...which I think will be a reasonably straightforward "squeeze". However, I do realise this brings me back to the original limitations of combining TV, Sat and FM together, when I need to make sure I have a good TV signal...

I won't be trimming down any of the coax cables currently there, rather I'll pull them up into the loft (as they are in continuous runs from the aerials/dish) then if this doesn't work out, I can at least go back to where I was before.

Sound sensible?

As a further aside...do triplexers differ much in quality? I really do need to have the MK one (linked above) in my lounge, but loft-side I'm flexible...

 

[Sureitsoff?]

i personally would keep the main dish feed on the CT100 and the others via the triplexer on the CT63 , but as the CT63 is fairly small you may still get both legs down the conduit as well as the CT100 and the cat5

let us know how you get on