Distribution advice needed

iognaid

I've changed to DTT and am using the UHF aerial previously used for TV3 and TG4. Up to this I distributed the signal (VHF,UHF) in the attic to other rooms by means of a Labgear distribution amp.
Now when I do this I only get TV3 and TG4 and RTE 1&2 are unwatchable. However if I wire the signal directly to the TV set I get all 4 channels perfectly. I can't understand this, what am I doing wrong? Help/advice most welcome

Peter Rhea

So you're saying that you previously used this amplifier without any problems & have changed nothing in the aerial setup? All you've done is get a Saorview capable receiver?

iognaid

Yes, exactly that. When I run the cable directly from the aerial by means of a simple coax connector rather than going through the distribution amp it works fine. Puzzled!

excollier

DTT can be fickle sometimes. It may be that the amp is a little too high in gain on some frequencies, or possibly the insertion loss is killing them, ie it's losing just enough to knock out those frequencies.
Only way to tell is use a meter and check, or another distribution amp to compare.
Another thought is that the gain is putting the existing analogue signal strength too high which will "swamp" the DTT tuner at certain frequencies, and lose some channels.

Peter Rhea

I think OP's referring to the loss of the VHF analogue channels. What's the model no. of the amp?

darth_maul

ok when you talk about rte 1&2 being unwatchable and TV3 & TG4 being fine is this DTT you are talking about?? whats the other channels on DTT like, also by unwatchable describe the picture,

The reason I ask is that problems on DTT usually affect all channels on the same mux to a greater or lesser extent as they are all on the one uhf channel and need to know you are not talking about analogue (loss of VHF in a UHF amp), but if it is indeed DTT your are talking about, what could be happening in this case is that the amplifier is adding just enough noise to send the signal over the edge of the digital cliff, whats needed here is a proper professional digital meter to measure the signal quality before the amp and after it. It could also be that the signal is too strong for the amplifier and causing cross modulation, again a good digital signal meter is the only way to diagnose that.

excollier

Ah, yes, good point, forgot about Saorview DTT being all on same mux, too used to Freeview and multiple muxes, where some can be lost while others are ok.

Ronnie Raygun

Nothing like confusing the issue before the precise nature of the OP's problem has even been properly established.

excollier

So sorry.

iognaid

Really appreciate the input so far. Will put a signal metre next week, of course its the logical place to start. Will report

iognaid

Thanks Peter, The model # of the Labgear amp: CM7296

darth_maul

darth_maul wrote: »

ok when you talk about rte 1&2 being unwatchable and TV3 & TG4 being fine is this DTT you are talking about?? whats the other channels on DTT like, also by unwatchable describe the picture,

If you answer the above it may well save you the bother

Peter Rhea

iognaid wrote: »

Will put a signal metre next week, of course its the logical place to start. Will report

Could you just confirm if the problem is with the analogue channels? And you definitely didn't change anything between aerial & amplifier?

Can't find anything on that particular amp, but there seem to be a number of newer versions. How many inputs does yours have & how are they labeled?

Schintzel

iognaid wrote: »

I've changed to DTT and am using the UHF aerial previously used for TV3 and TG4. Up to this I distributed the signal (VHF,UHF) in the attic to other rooms by means of a Labgear distribution amp.
Now when I do this I only get TV3 and TG4 and RTE 1&2 are unwatchable. However if I wire the signal directly to the TV set I get all 4 channels perfectly. I can't understand this, what am I doing wrong? Help/advice most welcome

Reading between the lines it seems like you installed dtt set top boxes at one or more locations? If you are looping the aerial lead from the stb (ant in) to tv (ant out) then maybe the lower vhf signals are being filtered out as the stb will have a uhf receiver only.

Sam Russell

Schintzel wrote: »

Reading between the lines it seems like you installed dtt set top boxes at one or more locations? If you are looping the aerial lead from the stb (ant in) to tv (ant out) then maybe the lower vhf signals are being filtered out as the stb will have a uhf receiver only.

No, Saorview is VHF as well, it's in the spec. Besides, the pass through is just that, a pass through.

sesswhat

Sam Russell wrote: »

No, Saorview is VHF as well, it's in the spec. Besides, the pass through is just that, a pass through.

But then we don't know if the equipment is saorview approved. Even if it is, is VHF required to be looped through effectvely by Saorview equipment, or merely processed by the tuner?

Vince Cable

iognaid wrote: »

When I run the cable directly from the aerial by means of a simple coax connector rather than going through the distribution amp it works fine.

This post would seem to suggest there's something up with his distribution box, not any receiver.

sesswhat

Maybe that test is taking the DTT box out of the loop as well? What happens if you connect aerial to TV through the new receiver?

Vince Cable

. . . or maybe there's no DTT box, just a Saorview compatible tv in the 'main' room & the problems are on other tvs.