How should portable and vehicle-mounted wireless megaphones be installed, powered, and operated?

Installation, Wiring, and Operational Guidelines

Correct setup and operational procedures ensure maximum acoustic performance and prevent hardware damage or safety hazards.

1. Battery Setup & Power Connection

• Dry Cell / Alkaline Battery Installation: Observe correct polarity (+/- orientation) when loading AA or C/D size dry cells into the battery compartment. Remove spent batteries promptly to prevent chemical leakage.
• Rechargeable Battery Packs (Ahuja LB20 / Li-ion): Insert the rechargeable pack into the handle compartment. Ensure the charging cable is disconnected prior to switching on the megaphone.
• 12V DC Vehicle Power Wiring: For vehicle-mounted models (e.g., MP89U), connect the provided DC jack cable into the 12V cigarette lighter socket or directly to the vehicle battery terminal with an inline fuse protection.

2. Flameproof Unit Safety Mandatory Protocol

For Ex d flameproof megaphones (model STJ30115):

• Charging Restrictions: NEVER charge the internal 3.7V Li-ion battery inside a hazardous Zone 1 or Zone 2 area. Charging must take place strictly in designated non-hazardous maintenance rooms.
• Earthing: Secure 1 internal and 2 external grounding points using copper earthing conductors to prevent static charge buildup.

3. Microphonic Feedback Prevention & Acoustic Positioning

Hold the dynamic microphone approximately 2 to 5 cm from the operator's mouth. Speak clearly directly into the diaphragm. Avoid pointing a detachable microphone directly back into the horn flare to eliminate high-pitched acoustic feedback (howling).