A non-Clansman Radio interface - VMARSmanuals

The VMARS Newsletter Issue 39Non-Clansman InterfaceInterface Box 2 - radioptt relayTr1*Operation.If you now set up two “CrewBoxes 2 set” and a singleInterface Box 2 set” you will getone operator position (selects Aset on his box plus +M on theright hand side switch), and thesecond operator or logger setshis box to the same settings. Bothcan now hear receive traffic, andwill get side tone (only if theconnected radio sets supportsmonitor or side tone), and eitheroperator by selecting IC on hisbox will be able to speak to theother operator.Further, extension to the outsideworld is simply achieved byextending the harness andadding more crew boxes.Crew Box 2 setHarness cablePin 3 Mic o/p to interface boxPin 4 Mic o/p to interface boxPin 5 GNDPin 8 Mic input from headetPin 9 Mic input from headetHeadset CircuitNotes:1. The transformer TR1 in the non-clansman interface box is a600Ω - 2x 300Ω mic transformer, but as this is a fairly rareitem, it is possible to use two standard 600Ω - 600Ωtransformers with the primaries in series to give the desiredeffect.2. It may be necessary to adjust the values of the resistors inthe base circuit of the relay switching transistor for satisfactoryoperation, depending on the gain of the transistor.5 February 2005