19-09-2016, 01:58 PM
I ought to add a note about safety when using Auroras, modulators etc with old TVs. Many sets have their chassis connected to one side of the mains. The aerial isolator in the set keeps mains away from the aerial. Unfortunately the isolators can fail with unpleasant results as we've seen above. Even worse, if nothing is earthed and the entire aerial distribution system goes live you've got a nasty shock hazard.
Hence I recommend:
1: Solidly earth the co-ax outer of an aerial distribution system. Mains earth is fine for this. If an errant set puts live mains on the co-ax it will at least blow a fuse.
2: Use an RCD in the power feed to the sets. Always sensible. Will trip on lesser faults that wouldn't blow a fuse.
3: Ensure that the chassis of each set is connected to neutral. Mark connectors that are reversible. At least this will reduce the likelihood of damage if something goes wrong.
For larger systems and workbenches consider using additional isolators. There's a good reason why every Virgin cable installation has one of these where their cable enters the house. At the Museum we use one in the feed from the sheds to the house to ensure that a fault at one end doesn't affect the other. We also use one in the feed to the workbench so that a duff set or accident there doesn't affect anything else. A DIY isolator, along the lines of Gryphon's balun will be fine if nothing else is available. Or even a couple of Y rated 1000p caps in a plastic 35mm film can.
Hence I recommend:
1: Solidly earth the co-ax outer of an aerial distribution system. Mains earth is fine for this. If an errant set puts live mains on the co-ax it will at least blow a fuse.
2: Use an RCD in the power feed to the sets. Always sensible. Will trip on lesser faults that wouldn't blow a fuse.
3: Ensure that the chassis of each set is connected to neutral. Mark connectors that are reversible. At least this will reduce the likelihood of damage if something goes wrong.
For larger systems and workbenches consider using additional isolators. There's a good reason why every Virgin cable installation has one of these where their cable enters the house. At the Museum we use one in the feed from the sheds to the house to ensure that a fault at one end doesn't affect the other. We also use one in the feed to the workbench so that a duff set or accident there doesn't affect anything else. A DIY isolator, along the lines of Gryphon's balun will be fine if nothing else is available. Or even a couple of Y rated 1000p caps in a plastic 35mm film can.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
