Converter, Frequency Shift Type CV-89A.
This American frequency shift adapter is powered from 115V AC supply and accepts audio signals from the 600 ohm output of a radio receiver. These signals are converted to single current on/off signalling that requires an external 120 volt loop supply having a grounded negative output. The wide and narrow shift audio signals are connected through their respective input connectors and pass through tuned filters to select only the required range of frequencies. Operating frequencies.-Narrow shift: centre frequency 1000 cps ± 1%, shift 10 to 200 cps. Wide shift: centre frequency 2550 cps ± 1%, width of shift 200 to 1000 cps. It also provides a keyed tone output for feeding remotely located telegraph equipment via landlines or radio links.