My PVR using the same cable gets all channels but the tv does not get any standard definition BBC channels or radio. The cable is split using a passive splitter before going in to the tv & pvr.
Just to clarify on the way the cable is split....
Are you saying that (
i) the a single cable comes in to the room, and then it goes in to a two-way splitter. Or do you mean that (
ii) the cable is split somewhere else and then the single cable loops through the PVR to the TV?
Is it
i or
ii??
If it's '
i', then the action of splitting will reduce the signal level by 3.5dB or more, but could also let in a dose of noise if the splitter is poorly shielded such as the one in the image below
Replace that with one either of these
For TV signals both of these do the same job and to the same quality. The difference other than shape and type of connectors is that the 66100 also works at satellite signal frequencies. You don't need that, but if it's more convenient for you then don't hesitate to buy the 66100.
Signal difference between the PVR and the TV
Whether the split is done
i or
ii doesn't matter so much for this next bit. Where it's split in-room then both the TV and the PVR should be getting the same signal level and quality so long as both fly leads are up to the job. There's more on that later.
The point here is that both devices are (or should be) getting what amounts to the same signal, so if there was an issue with the cable in the wall then the natural question would be why the TV is reacting differently to the PVR? If we presume that both devices are correctly tuned, then the real world answers are usually either there's a difference in the sensitivities of the tuners or there's a problem with the wiring in the room.
Tuner sensitivity would explain why one of the weaker muxes might be received differently between two devices. That doesn't appear to be the case with you though. This isn't the shopping channels on SDN 29 that's affected; it's the main SD BBC mux, and the BBC muxes are always transmitted at full power from a transmitter. Sudbury is a powerful transmitter; AFAIK 100,000W for BBC A.
Is it the aerial then? Again - site unseen - I would say it's unlikely. Not unless there's a problem with how it's mounted in the loft. But if there was then the TVs on the longer cable runs would be similarly affected, as would be the PVR, and neither of those situations is the case. Besides that, the BBC A mux is in a part of the gain curve where the aerial's reception is stronger rather than weaker.
Is it too much signal from the aerial? Without the booster in place you had trouble getting signal to this point. That wouldn't have been the case if the signal was already sufficient. I'm going to say then that this is unlikely. Besides, if too much power was the issue then the TV on the shortest cable run would have obvious issues, and you haven't said that's the case, so I'm leaning towards no again on too much signal, but I will circle back to this later depending on how your in-room wiring is laid out.
One further question... Does the affected TV have a HD tuner or not?
What this leaves us with then is either some problem with the wiring in the room or a problem with the cable to that room that's then exacerbated by the wiring in the room. For troubleshooting, it's sensible to eliminate the simple elements first.
Store-bought fly leads are a common cause of signal issues. They're lossy, and they're poorly shielded, and there's a longer-term issue with their construction which means that the acid in the solder used to join the pin to the centre core eats the connection over time. Since the whole thing is entombed in plastic it's impossible to see and check. A fault might show up if you use a multi-meter on continuity test or Ohms. RF is slightly weird in that a signal will 'jump' a gap or break if the distance is small enough. It's called capacitive coupling. The cable looks like it works with an RF signal but is massively more lossy. To a multi-meter measuring continuity or Ohms then the cable shows up as a break.
The simpler solution is just to replace them, but
not with new versions of the same thing.
Short recap... These are crap.
Replace with something like this.
A properly-made fly lead will have decent shielding and the sort of connections that can be checked for issues should the need arise. They're also far less lossy than the bought-in cables, and cheaper too.
You're unlikely to find these read-made in stores and so may need to buy a small reel of cable and some coax plugs to make your own. Where doing so, I'd recommend Webro WF100, Triax TX100, Labgear PF100 or Doncaster CT100 cable. They're all good 100% copper coax cables. Should that prove to be a little OTT for just a couple of short fly leads then I can supply you some made-to-length in either white or black with the appropriate male/female ends to suit your needs.
What about if the in-room signal cables are wired as ii?
If you're using the PVR loop-through connection - and presuming you've switched off any power saving feature in the PVR which disables power in the loop-through when the PVR is in standby (God knows who thought that was a good idea!?!) - then the looped signal often has a little amplification.
As we know with aerial amps, amplification increases power but decreases quality. If the signal is already marginal for some reason then this can tip the balance and stop reception. Generally any weaker muxes will be lost first, but if the cables are a bit dodgy then they can have a
notch filter effect which means that only certain frequencies are lost regardless of initial strength.
This could be the case with your BBC A signal.
Summary: replace the fly leads and splitter first to see if that's enough to fix the issue. It's
cheap and
easy to do, and a good idea in the longer term anyway, so the effort and cost isn't high. Also, if it doesn't work then you'll know for sure that going to the expense of having a new downlead fitted is justified because you've already ruled out the simpler solutions.
