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All posts by Chris.SE

Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.


This is an independent free help-site for people with technical and reception problems and has no direct connection with the BBC or any other broadcaster whether civil or military.

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Hi. Some basic checks, have you retuned at all recently? If so, check in your TV tuning section you are correctly tuned to Porlock's UHF channels which are C24, C27, C21 for BBCA/PSB1, D3&4/PSB2 and BBCB HD/PSB3.
Other signals can be received in your location and some of the recent weather conditions can cause Tropospheric Ducting/Temperature Inversion which could make such signals quite strong.

Porlock is a relay of Mendip and Mendip has had Planned Engineering in recent weeks and that may be affecting the signals at Porlock, nothing can be done about that, one has to wait for work to be complete. There are no recently reported faults or engineering at Porlock.

Have you checked your aerial hasn't been inadvertently disturbed, it should be pointing compass bearing 234 degrees (9 degrees W of SW) with the rods vertical, also check you haven't had any vermin chewing cables!

Your friend's caravan site is not in a "predicted" Freeview reception area. That doesn't mean that he wouldn't be able to get any reception as predictions aren't 100% but it does mean reception could be quite variable to poor. Reception may even be from an "out of area" transmitter. Do you know which way his aerial points and which way the rods are?

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Full technical details of Freeview
Monday 27 June 2022 1:48PM


You should get all 6 multiplexes with no real problem providing you have a good Group K aerial (a wideband would probably do), it should be pointing compass bearing 181 degrees that's virtually due S, and the rods should be vertical. Make sure there are no large metal objects or thick walls on the line of sight.

Check in your TV tuning section that you are correctly tuning to Lark Stoke's UHF channels -
The UHF channels are C26, C23, C30, C33, C36, C48 that's in the multiplex order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3,. SDN/COM4. ArqA/COM5 and ArqB/COM6.

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It depends on where you are in Caithness, it's a large area and reception in some parts could be patchy.
Where there is reception it is only the BBC National multiplex on Block 12B 225.648 MHz
There are no commercial multiplexes broadcast from Rumster Forest or Keelylang Hill.

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One source says the site is owned by BT. If the taller mast is the "slimmer" one of the two, that one could be the responsibility of the MoD.
As suggested by StevensOnln1, try asking Arqiva which organisation(s) are responsible for the masts and their maintenance.

As an aside information about lighting such obstacles may be found in

I haven't managed to find any information on the height of the tower, but my search wasn't exhaustive.

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Ted Slater:

Hi Ted. Just been having a recap on those previous posts. if you recall you did some quality and strength measurements with the aerial direct to the TV for each multiplexes UHF channel.
Results in this post all other equipment out of circuit and switched off. The results showed this decrease in quality and strength with increasing UHF channel !

I did mention at the time about doing the same but with just the filter in circuit. Could you do that and post the figures please.
Depending on results, that will hopefully give me a clue about the next possible check.

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