Full Freeview on the Sandy Heath (Central Bedfordshire, England) transmitter
 | Google Streetview |  | Google map |  | Bing map |  | Google Earth |  | 52.130,-0.242 or 52°7'47"N 0°14'33"W |  | SG19 2NH |
The symbol shows the location of the Sandy Heath (Central Bedfordshire, England) transmitter which serves 920,000 homes. The bright green areas shown where the signal from this transmitter is strong, dark green areas are poorer signals. Those parts shown in yellow may have interference on the same frequency from other masts.
Are there any planned engineering works or unexpected transmitter faults on the Sandy Heath (Central Bedfordshire, England) mast?
Sandy Heath transmitter - Sandy Heath transmitter: Possible effect on TV reception week commencing 22/04/2024 Pixelation or flickering on some or all channels 
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Digital television services are broadcast on a multiplexes (or Mux) where many stations occupy a single broadcast frequency, as shown below.
64QAM 8K 3/4 27.1Mb/s DVB-T MPEG2
H/V: aerial position (horizontal or vertical)
Which Freeview channels does the Sandy Heath transmitter broadcast?
If you have any kind of Freeview fault, follow this Freeview reset procedure first.Digital television services are broadcast on a multiplexes (or Mux) where many stations occupy a single broadcast frequency, as shown below.
64QAM 8K 3/4 27.1Mb/s DVB-T MPEG2
H/V: aerial position (horizontal or vertical)
Which BBC and ITV regional news can I watch from the Sandy Heath transmitter?
BBC Look East (West) 1.0m homes 3.7%
from Cambridge CB4 0WZ, 29km east-northeast (65°)
to BBC Cambridge region - 4 masts.
70% of BBC East (East) and BBC East (West) is shared output
ITV Anglia News 1.0m homes 3.7%
from Norwich NR1 3JG, 119km east-northeast (60°)
to ITV Anglia (West) region - 5 masts.
All of lunch, weekend and 80% evening news is shared with Anglia (East)
How will the Sandy Heath (Central Bedfordshire, England) transmission frequencies change over time?
| 1965-80s | 1984-97 | 1997-98 | 1998-2011 | 2011-13 | 12 Feb 2020 | ||||
| VHF | A K T | K T | K T | W T | W T | ||||
| C6 | ITVwaves | ||||||||
| C21 | C4waves | C4waves | C4waves | +BBCB | BBCB | ||||
| C24 | ITVwaves | ITVwaves | ITVwaves | D3+4 | D3+4 | ||||
| C27 | BBC2waves | BBC2waves | BBC2waves | BBCA | BBCA | ||||
| C31 | BBC1waves | BBC1waves | BBC1waves | ||||||
| C32 | com7 | ||||||||
| C33 | SDN | ||||||||
| C34 | com8 | ||||||||
| C35 | _local | ||||||||
| C36 | ArqA | ||||||||
| C39 | C5waves | C5waves | |||||||
| C43 | _local | ||||||||
| C48 | ArqB | ArqB | |||||||
| C51tv_off | SDN | ||||||||
| C52tv_off | ArqA | ||||||||
| C55tv_off | com7tv_off | ||||||||
| C56tv_off | COM8tv_off |
tv_off Being removed from Freeview (for 5G use) after November 2020 / June 2022 - more
Table shows multiplexes names see this article;
green background for transmission frequencies
Notes: + and - denote 166kHz offset; aerial group are shown as A B C/D E K W T
waves denotes analogue; digital switchover was 30 Mar 11 and 13 Apr 11.
How do the old analogue and currrent digital signal levels compare?
| Analogue 1-4 | 1000kW | |
| BBCA, D3+4, BBCB | (-7.4dB) 180kW | |
| SDN, ARQA, ARQB | (-7.7dB) 170kW | |
| com7 | (-13dB) 49.6kW | |
| com8 | (-13.1dB) 49.1kW | |
| Mux 1*, Mux 2*, Mux A*, Mux B*, Mux C*, Mux D* | (-17dB) 20kW | |
| Analogue 5 | (-20dB) 10kW |
Which companies have run the Channel 3 services in the Sandy Heath transmitter area
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Saturday, 21 February 2015
M
MikeB7:02 PM
David Nash : Do you still have the same problem?
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Sunday, 22 February 2015
D
David Nash 9:22 AM
Hi thanks for the replies.
It look like it could be a failed distribution amplifier as removing power from that seems to resolve the problem.
I initially thought the equipment was fine as the (poor) signal disappeared completely when I unplugged the aerial cable, indicating so I thought that it was supplying some signal.
Turns out the amplifier is cutting the signal, at least when powered up.
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J
jb3812:24 PM
David Nash : You should try a test by connecting the aerial downlead directly into the feed that goes to your TV? in other words bypassing the distribution amplifier, as an amplifier having developed a fault whereby it cuts the signal out "when powered" is something which is virtually unheard of, that is unless the amplifier is taking the signal slightly over the top strength wise resulting in the tuners input being overloaded, as this will block reception.
Your location of being at just under 7 miles from the Sandy transmitter, and with, according to the terrain indicator, with a clear line-of-sight to same being the reason for mentioning this.
I would though be interested to know the brand / model of the amplifier in question.
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J
jb383:16 PM
David Nash : In addition to that said, another possible reason for the problem could be that of a 4G transmitter having been installed in your area, the signal from said transmitter being received at a level just under that required to interfere with your Freeview reception, the powered distribution amplifier lifting it above this.
Of course, actual distribution amplifiers themselves "can" block reception, that is if the level fed into their aerial input socket is above a certain level whereby triggering instability (self oscillation) in the amps input stage.
That said, its still a bit puzzling as to how you are able to receive anything with the amplifier unpowered, that is if you are? and I am not just misinterpreting what you mean, as the output from most amplifiers when unpowered is almost negligible.
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D
David Nash5:48 PM
Yes it's a little odd I agree.
The aerial downfeed goes into the amp, and it has 8 outputs, only one of which is in use although some of the others have cables going to other rooms, but not connected to a receiver. The amplifier is Wolsey, described as "8+1" output. One output (the one I normally use) is marked "Full" and the others are marked 1-8.
This has been the same for >10 years and working properly until now.
With the amp on, the signal is very poor, some channels are detected by the TV but not all, presumably some muxes are not seen although I didn't bother checking which.
With the amp off, and all cables plugged in, signal is fine, all channels detected OK.
With the output from the amp unplugged, ie. just a cable to the TV, there is still a signal. I guess being only 7 miles from the transmitter the cable is picking up the signal itself.
Turning the amp on definitely breaks things.
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J
jb388:02 PM
David Nash: Thanks for the info re: distribution amplifier being used. However, there are two versions of this 8 way+1 amp. (1): being a two input model (334038) with each of the 8 UHF outputs having a gain of 11dB, full output being 18dB, and (2): a 1 input model (334044) with each of the 8 wideband outputs being 13dB, full being 23dB.
Irrespective of which model you have, try connecting the feed that runs to the TV into one of the 8 lower gain outputs rather than being connected into full, as this level of amplification (whether 18 or 23db) being used in a location such as yours is (in normal circumstances) grossly excessive.
Of course, I do appreciate the fact of you having been using this set up for 10 years or so, but something has obviously changed, and which I suspect as not necessarily being connected with your installation, but one never knows!
By the way, Wolsey also manufactures another 8 way+1 distribution amp called an "LTE" model, should by any chance you be using this model ? (albeit I doubt that you would be) disregard that previously mentioned regarding 4G, as the LTE model features built in protection against 4G transmitters.
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Monday, 23 February 2015
D
David Nash 11:13 PM
Hi again.
It's not the LTE model, as it precedes 4G by a long time.
I did actually try one of the lower gain outputs with no luck.
I guess I will replace the amplifier anyway.
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Tuesday, 24 February 2015
M
MikeB8:27 AM
David Nash : why replace it?
You don't seem to need the aerial, so an unpowered splitter might be fine. It would be cheaper and have little that could go wrong, and 4g is certainly not much of a worry.
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J
jb387:50 PM
David Nash - If the lower gain output test has made no difference to the situation, then I cant really see any way forward other than by replacing the Wolsey, but though with the replacement distribution amplifier being of the somewhat less powerful variety, as you only require the absolute minimum of gain just enough to compensate for the large number of outputs, whether they be presently used or not.
However, there is one final test that I would like you to carry out, that being, with the amplifier connected up in exactly the same way as it has been over the years but "not" powered up, which as you have said, results in all channels being detected, kill the signal whilst viewing any of the channels by powering up the amplifier.
The test being to remove the amplifiers aerial "input" connector and replace it with a short length of wire (3 or 4 feet) pushed into the middle of the aerial input socket, the question being, does this enable a picture of sorts to be seen? By the way, an old (non powered) set top aerial is ideal for this test if its coax connector is removed.
The reason for requesting this test is that I am beginning to suspect that the problem "might" be caused by instability in the amplifiers high gain input stage, (possibly by an electrolytic capacitor having dried out through age) the instability being triggered by the high level signal from the aerial being fed into the amps input stage, high gain stages being far more vulnerable to developing instability problems should anything be amiss component wise.
Purely out of curiosity, are you using a roof mounted aerial? and can you confirm (or not) that your Wolsey uses "F" sockets rather than coax types?
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D
David Nash10:47 PM
I will try that test when I get a chance, thanks for the suggestions.
To answer your other questions, the aerial is in the loft and the amp has the traditional (as I know them!) co-ax sockets, not F-connectors.
Mike: I am splitting to 6 room sockets which all have an outlet, I'd like them all to be usable without poking around under the stairs, although currently only one is in use. Hence an 8-way amp (obviously 6-way would do!).
An 8-way SLX amp is inexpensive on Amazon so I may as well.
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