Pro Intercom, Partyline Intercom MS300 Master Station

Three circuits rather than the usual two.
Circuits are linkable (A + B) or (A + B + C) with auto termination impedance adjustment.
-Each circuit’s termination can be lifted via rear panel DIP switches.
-Mic switch on each circuit can be tapped for locking or held and released for momentary.
-Full duplex, hands-free operation, in moderately noisy environments. (with optional noise-canceling gooseneck mic.)
-Front panel 4-pin XLR may be used for gooseneck mic. or headset.
-Gooseneck or headset mic. may be dynamic or electret. Lighted front panel switch sets choice.
-Front panel green LED indicates presence of 24VDC across the three circuits.
– Three front panel flashing red LEDs report trouble status of each circuit. Other circuits are not affected.
-System auto-resets when the problem is eliminated.
-While switching is all electronic, the audio paths remain analog providing comfortable long-term listening.

Each circuit has a characteristic impedance of 200 ohms at audio frequencies, allowing many beltpacks to be connected together without significantly changing the circuit performance. The termination networks are automatically removed and inserted during circuit linking to ensure a constant impedance for all circuits. The termination networks may also be man- ually removed by setting a switch on the rear panel, if desired. This may be useful when using an adjunct network, or if in- terfacing with a larger communications system.