Tech Support

Below are the most frequently asked questions for transmitters and receivers.


Are transmitters water resistant?

Pendant and watch style transmitters are water resistant to 60 feet of pressure. Alarm Electronics will replace at no charge any transmitter which is damaged by water in normal use. Because of the possibility of the seal being damaged with time and handling, if a transmitter is used in an environment which exposes the unit to water, frequent routine testing is a necessary requirement of use. Transmitters are not intended for constant exposure to water for extended times or exposure to high temperatures, chemicals, strong soaps, cleaning agents, solvents, etc. Users of these products should be made aware of these limitations. In addtition we recommend the PLS-style bands for the watch style transmitters which will see a water environment.

How long do the batteries last inside the transmitter?

The pendant and watch style transmitters are powered by lithium batteries which are not replaceable. Lithium batteries lose about 1-2% of their total capacity per year of shelf life and after 10 years should have 80% of their initial capacity less any discharge due to use. In the typical application the capacity for use is 10,000 operations of one second duration. The DW-101A auxillary transmitter batteries can be changed. The life depends on whether the input circuit is N/O or N/C and how frequently the transmitter is activated. If the input sensor circuit is N/C (normally closed) or the reed switch is used, the maximum battery life is typically 3 to 5 years due to the current drain required to monitor the closed loop. When the input circuit is N/O (normally open) and the reed switch is not used the life approaches the life of a pendant (10 years +) for seldom activated applications. The initial capacity is 50,000 activations (25,000 in supervised mode).

How do I know when the battery is low?

Each Transmitter sends a battery status every time it is activated to the receiver. The 811LX, 902L, 904L and 601A receivers/decoders have a low battery output which is activated if the transmitter sends a "LOW BATTERY" condition.

What about encoding?

There are approximately 65,000 possible transmitter key code combinations. The transmitters are encoded at random unless otherwise requested by the customer. Matched sets, or specific key code sequences are available at no additional cost.


What will cause a decrease in range?

Obstructions by metal or radio absorbent materials which either absorb the radio energy from the transmitter or reflect the energy to another direction preventing the signal from reaching the receiver. Reflections also cause multi-path effects where there will be areas of poor reception within a few feet of each other. Multi-path effects can be substantially eliminated by using 2 receivers a few feet apart. Location of the receiver is also important. In general the higher elevation the better. For instance, it is better to locate the receiver in an upstairs room than in a basement if it is desired to have reception outside the home. Obstructions such as aluminum siding or foil insulation/wall paper will block 90% or more of signal. In commercial installations place the receiver away from metal partitions and below suspended ceilings.

What about Interference?

EMI/RFI electromagnetic interference and radio frequency interference. Electrical or radio interference will not cause false alarms but may cause a substantial decrease in range. Typical sources are alarm panels with high clock rate micro-processor controls, radio scanners, local high power radio stations, defective dimmer controls, etc. For maximum immunity to EMI/RFI use the extended range receivers 811LX, 902L, 904L, 800LX which are superheterodyne receivers with good shielding and helical resonator antenna pre-filters.