UHF signal strength

That reminds me of when I was trying to tell a colleague how to pronounce my Greek colleague's name "Asthanostheas" I got as far as "Ast" and he said "Astronomical?" I said "Just call him Thanos" - which was what he seemed to like going by, probably because it was a Greek god.

Reply to
Commander Kinsey
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Which sort of indicates a low signal level for the HD MUX(s). Why though? Have you ever changed the aerial? With all the shuffling about that has gone on with the clearing fo 800 and 700 MHz, your aerial may now be the "wrong" group for the frequencies used by the HD MUXs in your area.

Reply to
Dave Liquorice

The LabGear amp contains Class 3 4G filter providing 45dB interference protection

Reply to
rick

Which was the point of the OP

Reply to
rick

The loss will be 50 to 60dB so yes, you will need line amps. As you say, they need to be correctly positioned along the cable. Do you use line amps with built-in equalisation? Do you use direct-burial or sheathed cable?

It would be technically better to use a large diameter cable such as CT167, but I realise cost would be a factor.

Bill

Reply to
Bill Wright

Sometimes reiteration is necessary.

Bill

Reply to
Bill Wright

Where are you?

It doesn't sound as if you have a main station nearby.

When I was fixing aerials for rental chains in the 1970s excessive signal levels were a constant problem in West and South Yorkshire. The usual tx was Emley Moor, and if it was line-of-sight and you were closer than 15 miles the signal levels would be +23dBmV (analogue of course) or more. Really close you might get +35dBmV but it didn't increase much as you got even closer because of the vertical beamwidth of the tx.

In the 70s and 80s the rental firms mostly used chassis that were intolerant of levels above +16dBmV (they were also intolerant of levels below +3dBmV!). That was OK while the sets had a little preset on the back that was a variable attenuator. But when that was discontinued the problem became as much financial as technical. Attenuators were 50p. The gross profit on a new aerial job was £4.75. I resorted to faraday loops. Most installers resorted to putting one strand of braid onto the centre pin in the plug.

Bill

Reply to
Bill Wright

Er.... I dunno what that is. I just bought inline amps that are powered off the 12VDC present on the cable from the Sky box. They're tiny little things, not much bigger than the two connectors on each end.

Just the standard cable everyone has from Sky dish to Sky box at home, but longer. It's not buried, it's going through false ceilings.

It seems to work fine with the little amps.

Reply to
Commander Kinsey

Central Scotland. It's actually worse in the town where the transmitter is, as the tall buildings block the signal.

It's amazing anything works at all :-)

Reply to
Commander Kinsey

Because losses on cable are greater on higher frequencies than on lower ones, the line amps should really amplifier the higher frequencies more than the lower ones, to compensate for it. This is called 'equalisation'. Some line amps have a fixed amount of equalisation ('gain slope') and some are adjustable. Have a look at the instructions for the ones you use. Also look at Triax 370650

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I have a lot of these surplus and brand new if you want a bargain.

Yes you're generally going to be OK but if you have problems with higher muxes consider thicker cable and/or equalising line amps.

I hope you make sure no section of the cable is permanently under water...

Bill

Reply to
Bill Wright

I just bought the cheap ones and they seem to work ok.

The signal strength to all boxes is quite satisfactory. Mind you I did also use a very large dish. The management were mildly irritated when they saw the size of it, especially as I didn't tell them I was installing it. It replaced a cable TV line which was damaged by extensive building work, and Telewest or whatever they call themselves refused to fix it without a tremendous fee, plus they wanted to know how we'd been getting their services for free for the last 10 years :-)

If the water got to 12 feet above ground level, we'd have greater concerns.

Reply to
Commander Kinsey

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