Hopefully you are using decent balanced wire or fairly standard telephone lines from the remotes to the base station equipment.
All remotes should bridge (high impedance - CPI says their units bridge about 5,000 ohms each remote) the telephone line to the base station equipment with the exception of one "terminated remote", which is the one placed the furthest on the line(s) physical distance from the radio. Multiple remote setups in different location buildings invite serious hum problems. You'll be fighting the wires and then the ground loops at the equipment end. A hint is to actually try and observe the hum frequency... Is it 60Hz, 120Hz or something else. The CPI remotes I just installed were preset for -10dB, which is not the value I use. Check your levels once you get everything sorted out. There's a trick to finding ground loop problems at the radio equipment end... If you need help/ideas... email me direct for more leads. cheers, skipp > Joe <k1ike_m...@...> wrote: > > While the topic of tone remotes came up, I have a question about > configuration. > > I help to maintain a remote base system in my town. The radio is a > Motorola DeskTrac remote base. Connected to this are three CPI TR-10 > tone remotes. One of the tone remotes is at the Desktrac location, and > the other two are on two separate cable pairs to different locations. > I'm not quite sure as to how the three circuits should connect > together. CPI documents state that one should be in the 600 ohm > terminated mode and the other two in the 5000 ohm mode, but this is when > the three are on the same phone line. This does not work well, so I had > to put them all in the 600 ohm mode to make them work properly with no > ground hums. What I would like to do is put 600:600 ohm isolation > transformers on each of the remote circuits to isolate them and > hopefully eliminate the little ground hum I still have. > > I'm wondering if there is a better way. > > Joe >
