Telex 38109-977 manual Moisture / Contamination Protection, Magnetic Fields Hum Problems

user stations will normally continue to operate if one can only figure out a way to flip the switches and touch only the knobs.

Moisture / Contamination Protection

If, in the field, a soft drink or something like it is spilled into the equipment, the equipment can be dismantled and cleaned gently with clean water. After the equipment is dry it can be returned to service. If this happens fairly often, residues in the water can be deposited on the equipment. It should be noted that a build-up of contaminates and humidity can cause audible noise on the intercom line. If it is likely that the equipment is continually to be exposed to contaminating liquid, suitable plastic covers should be employed. It may also be necessary to add a plastic coating as described above. When using equipment in the rain always protect the equipment with plastic covers - also, make sure all cable connectors are lifted out of the mud or snow and protected with plastic bags. Rain, mud and snow in connectors can cause considerable audible noise in any communications system.

Magnetic Fields: Hum Problems

When the balanced type of intercom equipment is used, it is still possible to induce hum into the system by placing or locating user stations or system interconnects near a hum source, such as, power transformers or electrical switch panels or lamp dimmers. When the microphone switch is turned on and a dynamic microphone headset is used, the dynamic microphone is a sensitive antenna for magnetic fields. Often, operating personnel will go on a break, leave the microphone on and lay the headset on equipment with power transformers or near TV cameras or monitors with vertical deflection yokes. This is the reason for the system microphone turn-off scheme (Mic Kill).

SUMMARY

(Defining and Meeting Your Needs)

1Application Block Diagrams are a good starting place to define a system.

2The generic block diagrams show a basic small system and how things plug together.

3A generic system could used in a small television studio production, an outside television field production (such as ENG and EFP) or an industrial test of a large system (such as an aircraft).

4A generic system can be created using almost any Party-Line system. Audiocom, Clear- Com, and RTS TW systems block diagrams are shown.

5A switch on the Audiocom PS2000 two channel power supply can combine channels into one large Party-Line.

6Equipment available from any one of the three illustrated manufacturers intercom systems can be assembled into a two-channel system.

7A two-channel system can be used for a small TV operation (Studio or Truck) or cable access. One channel can be used for the director and crew, and the other channel can be used as a public address or stage announce system. The stage announce system can cue talent for the show, or allow the director to talk to the performing crew and talent during rehearsals.

8All three manufacturers make equipment suitable for theater applications use. Again, one channel of a two-channel system can be used to cue the actors.

C h a p t e r 3 - D e s i g n o f P a r t y - L i n e I n t e r c o m S y s t e m s 41