Digi TV switchover question

MarrowFarmer

I have 6 tv's connected to a main ariel with a booster dowstairs on the main tv's connection, all of them have worked fine before the first phase of our switchover* and all still work fine after retuning. All except the main tv downstairs, all the BBC channels break up badly now. (*East Midlands area)

I was lead to believe the signal strength would increase not decrease. Any chance my signal will improve after the second phase or is this what I'm stuck with?

Kurtis_Blue

maybe that the signal is now too strong, especially as the one tv breaking up is the closest to the amp.


Try, fitting a attenuator to the tv downstairs or replacing the amp with a passive splitter.

cajef

Kurtis_Blue wrote: »

maybe that the signal is now too strong, especially as the one tv breaking up is the closest to the amp.

Exactly the problem I had, the main mast for this area is only approx. 1 mile away and is clearly in view, after the switchover I had to put an attenuator in the main aerial feed as the TV tuner was being overloaded.

MarrowFarmer

Wierd!

I tried an attenuator, made no difference so I moved the booster power to another TV, still no difference. Stuck an old freeview box on the main tv and it works perfectly! Annoying thing is the box that is breaking up is a hard drive one so looks like I might have to splash some cash :mad:

Why the hell would would switching analogue off kill my box???

Kurtis_Blue

Most PVR freeview boxes are (basically) two tuners in one box, so it requires more signal.

yorkie98

Kurtis_Blue wrote: »

Most PVR freeview boxes are (basically) two tuners in one box, so it requires more signal.

Not true, dual tuner boxes loop the signal thru from tuner 1 to tuner 2 so there is no loss of signal, it's not like the signal is split then sent to each tuner.

WIth reception problems like this, the first rule is to try the aerial connected direct to the problem set (no amps, splits or anything) and see what you get. If reception is good then it's a distribution problem. It does sound like it's likely to be overloading as the only change to the BBC mux is an INCREASE in power.

What strength of attenuator did you try and what transmitter are you on as it would be useful to try to match the attenuator value to the amount of transmitter power increase. This could be as much as 20dB or more in some cases. Failing that, try a variable attenuator and a bit of trial and error, these are not much more than a fixed one.

Kurtis_Blue

It doesn't matter whether you cable the units in parallel or series you cant counter basic physics.

TimothyEBaldwin

In most (all) areas the BBC mux will change channel, and will change from 2k mode to 8k mode. The change of channel may result with it clashing with local sources of interference; check that you have no equipment with a UHF modulator (eg. the digibox itself) with the output tuned to the same channel as the BBC mux.

MarrowFarmer

TimothyEBaldwin wrote: »

In most (all) areas the BBC mux will change channel, and will change from 2k mode to 8k mode. The change of channel may result with it clashing with local sources of interference; check that you have no equipment with a UHF modulator (eg. the digibox itself) with the output tuned to the same channel as the BBC mux.

Hmmm sounds like a possibility. Now if only I knew what that meant and how to check

yorkie98

MarrowFarmer wrote: »

Hmmm sounds like a possibility. Now if only I knew what that meant and how to check

In laymans terms, your aerial should connect to your digibox first as if you have a VCR first (for example) it may output a signal which then passes on into your digibox and causes interference.

yorkie98

Kurtis_Blue wrote: »

It doesn't matter whether you cable the units in parallel or series you cant counter basic physics.

Nobody said you could but whatever method is used, a dual tuner box does NOT need more signal than a single tuner, these boxes have circuitry included which compensates for any such losses, the same way as when you loop the aerial cable thru a VCR, it does not reduce the signal that then passes on to the TV.
The simple fact is that some boxes will require more signal than some others due to the different sensitivity of tuners used and manufacturing quality etc but the number of tuners is not a factor.

None of this however is particularly relevant to the problem th OP is having so I suggest we move on and get back on topic.

Oh and just for the record, I am a former TV/Satellite installer of 20 years experience and I now work as a broadcast engineer so I have the credentials to know what I'm talking about.