[ConfusedYagi]

My location: Harrow, N.W. London.
Transmitter: Crystal Palace.
Aerial: Horizontally polarised Loft mounted 10 element yagi, with mains powered mast-head amplifier.
Coax - standard, all running internally through the house.
TV: Sony KDL26S5000 LCD

As of today 27/12/2010 I cannot receive any digital channels, including radio and channels 1 to 5 analogue are very grainy.

This follows a month of partial loss of Freeview digital which started at the end of November 2010.

Contacted the BBC in early December who advised that transmitter work was ongoing until the 10th December 2010
- "Dear Mr *******

Reference CAS-4491**

Thank you for contacting the BBC.

I understand you've been experiencing reception problems recently.

Having checked our database, you most likely receive your signal from the Crystal Palace transmitter and I can confirm that it's currently undergoing work to prepare it for the digital switchover. The work is scheduled to be completed by the 10 December but there will be times when it is operating on reduced power and during these occasions, digital users will experience reception problems.

I hope you find this information useful and thanks once again for taking the time to contact us.

Kind Regards

Peter Thompson
BBC Audience Services"

Situation hadn't improved as of last wednesday (22/12/10) so I reported the loss of signal again - no reply yet.

At that time I was still able to receive Channels 1-5, 8,9, 80 =81 i.e. most BBC.

Now, i've got nothing on digital.

Whilst I appreciate that there have been tropospheric ducting conditions over the UK affecting transmissions, it was also quite clear from the signal level indicator on my set that the transmission power eminating from CP has been down all through December and that this has varied by station throughout the month.

Yet someone on another forum located at Borehamwood (on the fringes of NW london) was having no problem at all.

Freeview on Crystal Palace TV transmitter | ukfree.tv - independent free digital TV advice


Can anybody on here explain what's happening and why there is so little advance information of signal outages coming from the BBC.

IMHO, judging from the reports of loss of service round the country over the last 18 months, the so-called "Digital switchover" has got to be the biggest C*ck-up in broadcasting history - I'm old enough to remember the more or less seamless introduction of BBC2 (apart from the opening night London wide power failure), Ch4 etc on analogue.


Nick

[Gavtech]

Originally Posted by ConfusedYagi

My location: Harrow, N.W. London.
Transmitter: Crystal Palace.
Aerial: Horizontally polarised Loft mounted 10 element yagi, with mains powered mast-head amplifier.
Coax - standard, all running internally through the house.
TV: Sony KDL26S5000 LCD

As of today 27/12/2010 I cannot receive any digital channels, including radio and channels 1 to 5 analogue are very grainy.

This follows a month of partial loss of Freeview digital which started at the end of November 2010.

Contacted the BBC in early December who advised that transmitter work was ongoing until the 10th December 2010
- "Dear Mr *******

Reference CAS-4491**

Thank you for contacting the BBC.

I understand you've been experiencing reception problems recently.

Having checked our database, you most likely receive your signal from the Crystal Palace transmitter and I can confirm that it's currently undergoing work to prepare it for the digital switchover. The work is scheduled to be completed by the 10 December but there will be times when it is operating on reduced power and during these occasions, digital users will experience reception problems.

I hope you find this information useful and thanks once again for taking the time to contact us.

Kind Regards

Peter Thompson
BBC Audience Services"

Situation hadn't improved as of last wednesday (22/12/10) so I reported the loss of signal again - no reply yet.

At that time I was still able to receive Channels 1-5, 8,9, 80 =81 i.e. most BBC.

Now, i've got nothing on digital.

Whilst I appreciate that there have been tropospheric ducting conditions over the UK affecting transmissions, it was also quite clear from the signal level indicator on my set that the transmission power eminating from CP has been down all through December and that this has varied by station throughout the month.

Yet someone on another forum located at Borehamwood (on the fringes of NW london) was having no problem at all.

Freeview on Crystal Palace TV transmitter | ukfree.tv - independent free digital TV advice


Can anybody on here explain what's happening and why there is so little advance information of signal outages coming from the BBC.

IMHO, judging from the reports of loss of service round the country over the last 18 months, the so-called "Digital switchover" has got to be the biggest C*ck-up in broadcasting history - I'm old enough to remember the more or less seamless introduction of BBC2 (apart from the opening night London wide power failure), Ch4 etc on analogue.


Nick

Welcome to the forum Nick.



If you have been having trouble all this time, it strongly indicates that the problem is with your installation and not an issue of transmission.

Crystal Palace has no engineering work currently which is interrupting transmissions.

See here.

You need to get your aerial installation checked out.

[Rodders53]

Your aerial installation is your problem, not the BBC transmissions..... especially when you describe your aerial installation. The work at Crystal Palace would have meant operating on reduced power - but a properly installed aerial installation should cope with that.

Depending on where you are in Harrow you might get better signals from the Hemel Hempstead transmitter rather than Crystal Palace. (This is a vertically polarised transmitter).

Check out all your aerial cables and interconnections. Try by-passing / removing the amplifier as that may have a fault. Any crushed or damaged cables could give problems. Corrosion or rust on the plugs and sockets likewise. Even one tiny stray whisker of the outer braid near to the centre conductor could degrade the signal enormously.

One of your neighbours between you and the transmitter hasn't built up into their loft have they? (Foil-backed insulation and plasterboard will very effectively block TV signals).

[grahamlthompson]

Additionally check the coax from the aerial for water ingress if the lead runs externally. Any abrasion of the outer insulation will let in water.

[ConfusedYagi]

I don't thinks its the leads or plugs because none of those have been touched/renewed in the last 6 months and the system was operating fine up until the end of November with 100% signal strength on all channels. In actual fact when i moved from a Sony 14" CRT + Goodmans GDB2 digital box to the integrated digital tuner of the current Sony LCD I had to remove the set-top amplifier from the line because the its was overdriving the RF signal - with only a mast-head amplifier all the signals were showing 100% strength.

I've just done some tests in which I connected a portable omni directional UHF aerial directly to the Sony.This aerial has an integral moulded coax plug. I attempted to retune the Sony both automatically and manually - No joy. Couldn't detect a digital signal. that's v unusual.

Substituted the same omni aerial for the main yagi in the loft, plugging it in as the input to the mast-head amplifier. Again no joy.

Plugged the same omni aerial in a Win TV HVR 900 TV tuner USB stick and then put the stick into my main desktop (Located at first floor level), downloaded the drivers and attempted to tune using Windows Vista 64's Media Centre software. Once again, could not detect a signal. And I have used that unit in exactly the same configuration before with good (Not spectacular) results.

Also, i'm located end of terrace, with the yagi pointing through the roof tiles into thin air. No immediate obstruction for 150 yards. I would imagine that Harrow-on-the-Hill is the major obstruction to signal propagation line-of-sight, but I've never had any problems with that in 25 years at this location.

Looks like either the transmitter bods have turned the wick down or something has popped-up in the line-of-sight building wise.

Whatever it is it must be substantial as I can only receive C4 & 5 PM on analogue.

I'll have to pop the usb stick + laptop in the car and go done the road a bit until I get a decent signal.

Myself, i think its definitely work being done at CP in preparation for the DSO.

Wasn't there a switch back planned to a different type of mux to allow auctioning-off of further airspace and that the type of Mux being switched to required more power in order to output the same signal - or is that issue ancient history now ?


Nick

[Gavtech]

Originally Posted by ConfusedYagi

I don't thinks its the leads or plugs because none of those have been touched/renewed in the last 6 months and the system was operating fine up until the end of November with 100% signal strength on all channels.

...


Myself, i think its definitely work being done at CP in preparation for the DSO.

Your conclusions are extraordinary.

CP serves millions of people.
If what you believe to be the problem was true, these forums would be awash with complainants from your area.

Officially - CP is broadcasting as normal... therefore it seems almost inescapably true that there is some issue with your aerial installation...or perhaps some change in your local geography albeit this would be very unlikely.

Have you asked neighbours what their reception is like?
Are you using any devices with HDMI cables as these can knock out UHF reception? If so - remove any to test.

Experienced contributors here have shown possible reasons why this may have occurred and have suggested good testing measures to attempt to find the cause and to hopefully achieve a remedy.

For some reason you have chosen to ignore this wisdom and the suggested remedial action which may point you to a solution...and if that is the case, I don't think we can help you any further.

[ConfusedYagi]

Apologies for going over the top. This has been driving me up the wall.

I believe I've now traced the problem to a partially disconnected co-ax connector on one of the fly leads between the TV set and the wall socket. The connector was in the socket, but not fully pushed home. This may have occurred when I added an additional set-top amplifier at the beginning of the month to counter the admitted signal strength reduction at that time. i.e. in solving one problem I caused another.

All appears to be rectified now. Freeview signal strength 100%. Personally, i'm astounded that the signal strength sensors in the TV were that easily fooled - I presume its just purely based on voltage.

Many thanks for puting me back on the right track.


Nick

[Gavtech]

I'm delighted to hear you have sorted it out.