1-18
Getting Started
Model 820 Technical Reference Manual
Internal battery life is approximately 16 hours. (Refer to the
description in
Chapter 2
of this manual for additional battery
information.)
The cable CBL116 SLN serial connectivity kit, which allows
connection of the 820 to a PC or modem, provides the
connection of an external power adaptor such as the PSA017
or similar
Alternatively, you may use an
external power source via pin
1(GND) and pin 4(+) of the 5-pin
connector. To do this, order cable
#CBL035 from Larson Davis. The
Model 820 accepts 7-16 Vdc @ 30
mA and is internally fused at 0.5 A.
Environmental Considerations
The Model 820 sound level meter can be both used and stored
in a wide range of temperatures, free of moisture and non-
condensing humidity conditions. Moisture will cause the
breakdown of an air condenser microphone. Some precautions
should be taken. For example, allow the Model 820 ample
time to adjust to abrupt temperature changes. Condensation
may form inside a cold Model 820 if it is brought into a warm
room or vehicle and may persist long after the outside case has
adjusted to the ambient temperature.
Also, temperatures inside closed vehicles can reach excessive
levels.
Therefore, do not leave the instrument in direct sunlight
in a vehicle.
A simple safeguard is to keep the instrument
inside a sealed foam insulated case or bag with desiccant silica
gel, available at photographic equipment stores or from Larson
Davis.
Preparing to Use the Model 820 - Connecting the Mic/Preamp
Before powering the SLM, carefully thread the microphone on
the preamplifier. The microphone bias voltage is not
dangerous, but installing or removing the microphone with the
instrument on may damage the electronics. Insert the 828 in
the nose cone or extension cable by lining up the latch button
with the channel in the mating connector. The small black dot
should click and protrude at the base of the 828 after insertion.
It must be depressed completely to remove the preamplifier
from the mating connector.