05-08-2012, 07:47 PM
Just a last couple of comments 'cause I don't like the idea of you heading into a Pit with no communications.
In a lot of American Pits they send and receive rf over the Trolley wires - they use Trolley Pole Locos and little cars when they're well away from the face. It works reasonably well, so I suspect a single wire strung along the roadways should work. I don't know what frequency they use but I could find out.
You could use (effectively) a Telephone, either with a pair or a single wire and Earth. Actually a Telephone is a bit of an overkill unless you have a couple of 'Buttphones' handy. The usual method is to have a battery powered amplifier with a Press To Talk (PTT) switch. You clip it to the line or lines and press the switch to talk, using the LS as a Microphone, then release the switch and listen. Generally you need a simple Signal Detector when listening otherwise you'll flatten the batteries.
Alan
In a lot of American Pits they send and receive rf over the Trolley wires - they use Trolley Pole Locos and little cars when they're well away from the face. It works reasonably well, so I suspect a single wire strung along the roadways should work. I don't know what frequency they use but I could find out.
You could use (effectively) a Telephone, either with a pair or a single wire and Earth. Actually a Telephone is a bit of an overkill unless you have a couple of 'Buttphones' handy. The usual method is to have a battery powered amplifier with a Press To Talk (PTT) switch. You clip it to the line or lines and press the switch to talk, using the LS as a Microphone, then release the switch and listen. Generally you need a simple Signal Detector when listening otherwise you'll flatten the batteries.
Alan
