Bad TV Signal

[kevin01]

I have always had a bad tv signal in my house which is doubley confusing bearing in mind I am only a few miles fom the Bedmond tranmittor.
Several years ago I had an amplifer fitted and this improved the situation but I still wouldn't have considered the reception as ideal except on the one tv that plus in directly to the amplifier.
I have been doing up the living room, this necessetated redirecting the incoming cables from the aerial and refitting the aerial junction boxes in the walls.
The reception isn't much better than having no aerial connection at all.
I assume that this is a bad connection somewhere but I have checked out all the junctions and they appear fine.
Why is the signal so bad?

[plumbbob]

There could be a whole raft of problems causing bad reception. The aerial could be ought of line, a building could be blocking the line to the transmitter, the aerial itself could be faulty, there may be a break in the downlead, the downlead may be poor quality and losing the signal, the lead may be too long, there could be a short at one of the junctions.

I would start by replacing the downlead with a good quality cable and see what happens. What sort of signal do your neigbours have?

[kevin17]

The downlead is certainly very old, in excess of 30 years, from before I moved in.
A new aerial was fitted several years ago when the amplifier was fitted, by a neighbour who was an aereal installer as it happens.
At the time it was ok but since then due to work in the house the route the cable takes has changed and the downlead has been cut and joined to a newer downlead into the house so I suspect this join.
I will have a go at remaking this joint, if it doesn't work then I will get an installer in as I am not going up on the roof.

[ericmark]

Find your nearest Radio Ham and ask him aerials are normally dead give away as to where they are. They will normally be very helpful. Some pointers the signal may be too strong and bouncing of things so giving mutli signals out of phase. Also too weak, and water in coax will really mess things up. As to aerial fitters I went to my local one who chatting told me some of the daft requests he got. Like stacking aerials on top of each other. My son and I had a job to keep a straight face. We had assisted in setting up an array of 9 aerials all in phase to bounce signals off the moon an knew stacking aerials was common for Radio Hams. Joining cables is asking for problems.

Eric

[kevin17]

Interesting that you mentioned water in the co-ax as I was wondering if moisture was getting in the cable join. I have got a waterproof junction box to fit so I better do that right away.

[ericmark]

Sorry to say once water get in coax renewing is normal only cure. It is a balanced feed and water makes it no longer 75 ohm and losses become too great. Testing with ohm meter will not show faults you would need a signal generator and oscilloscope to test far easier to renew. From electrical whole sale to too expensive you will get whole role for less than you get short length at B&Q

[plumbbob]

I once had water feeding all the way from the roof down the airspace in the cable and forming a puddle at the back of the TV!