Dave, If you want to "bridge" a balanced line to listen, the three operative precautions are (a) make sure you isolate both lines from ground, (b) make sure the device you use for monitoring has an input impedance significantly higher than the nominal line impedance, and (c) make sure to protect your monitor from DC voltage.
A battery-powered audio amp made from an LM386, a 5K input level pot and two capacitors works great. (It's unbalanced, but isolated from ground.) Add a 2.2K resistor ahead of the input coupling cap if you want a little more safety. I'm going to date myself here, but I still have a Brush Clevite high-Z dynamic headphone which works well for this. 73, Paul, AE4KR ----- Original Message ----- From: ve7ltd To: [email protected] Sent: Monday, March 30, 2009 11:22 AM Subject: [Repeater-Builder] Motorola Tone-Remote system troubleshooting question I don't fully understand the concept of balanced lines, and I don't want to damage any of the equipment by connecting something I shouldn't to it.
