John, The professional sound and recording industry addressed this problem long ago, when wired microphones and other pickups needed to be run several hundred feet from the performer on stage to the mixing board. We used balanced twisted pair shielded cable with XLR connectors on each end. A device called a "Direct Box" is used to convert unbalanced to balanced, and also avoid ground-loop issues. Since it is important to have a high-quality transformer in a direct box, I made my own with units from Jensen Transformer- a company that is still in business today.
http://www.jensen-transformers.com/ 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of JOHN MACKEY Sent: Friday, February 26, 2010 10:49 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] LOOONG audio runs I have a odd situation where I need to run long audio cables between my repeater controller and two repeaters. In this case, the repeater controller will be connected to 2 repeaters in the same cabinette. The other two repeaters will connected thru about 140 feet of wiring to the other side of a building. I am thinking of using balanced audio wires for the long runs and using Henry Engineeering boxes to convert between balanced/un-balanced at each end. Anyone ever done long audio runs like this? Am I over engineering it and unbalanced will be good enough? I use the Henry Engineering boxes for several audio conversions in broadcasting, here is a link for what they are: http://www.henryeng.com/matchbox.html <http://www.henryeng.com/matchbox.html>
