Which of these is CT100 cable or equivalent?

Lobster · 2007-01-16T18:03:23+00:00

I need to order up some more coax cable - this is for the downlead on a terrestrial aerial (currently analogue) and for feeds from a passive splitter to two TVs. May as well ensure it's futureproofed by being digital-compatible.I know I should get CT100 grade for this(?) - ideally I would like to include it in a Screwfix order I'm compiling but could anyone tell me which of their offerings is appropriate? Presumably the el-cheapo stuff isn't; but what about H109F, PF100, RG59, "Satellite Cable", and RG6? All double-dutch to me. See list at:Can these be simply "ranked" in order of efficiency or something (in case I have to decide between lengths/colours etc)?Thanks for any advice.David

Jan 16, 2007 27 Replies

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harrogate3 19 years ago

twisted

In the radio business these days it is more common to use Andrews LDF series - that is low density foam filled. The type used in older days and especially for high powered Tx is the FHJ range which uses a helical polythene insulator. The reason for the latter? Because you can blow air through it to keep it cool.

The TV feeders at Emley are - I believe - aluminium and are about six inches diameter. DAB from the bottom of the tower uses something that looks like FHJ7-50 at about 2" diameter.

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Ashley Booth 19 years ago

The TV feeders were made by a German company called KableMetall (sp?). Can't find much on the web, they seem to have been taken over by a French company.

They also supplied waveguide to one of the Goonhilly dishes.

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tony sayer 19 years ago

Sounds about right and only 1.45 dB loss;))

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>DAB from the bottom of the tower uses something that

Usually in TV practice made by the Andrews corporation. Up to around 6 inches in diameter and more often than not solid sections and pressurised by dry nitrogen to keep the damp out!....

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Ashley Booth 19 years ago

When working at a satellite tracking station in the 60s I had the job of logging the pressure in all the feeders. This was to spot leaks which usually meant the farmer had hit a cable with his machinery.

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Terry 19 years ago

When I saw the Band I transmitter at Crystal Palace in the early 60's - Channel 1 (45.0MHz Vision, 41.5MHz Sound), the sound/vision diplexer was a magnificent piece of plumbing cooled by distilled water! A float viewed through a little glass window read 20L/min, IIRC.

Terry

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Bill Wright 19 years ago

Yes it is, I've seen it and touched it. You couldn't fit a Poundshop belling plug on it that's for sure. I hope the gyppos never get in there with their chainsaws.

Bill

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Bill Wright 19 years ago

That very good figure could be one reason why they had all that bother a while back, when they were radiating a 'ghost' on BBC1 analogue. Didn't it turn out to be due to a mismatch at the top end of the feeder?

Bill

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