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EleclroVoice
e
Commercial Microphones
Description
These microphones were designed for com-
munications and paging applications. Both
models are also useful in amateur radio, CB,
aeronautical and commercial base station
installations.
The US621L is an omnidirectional dynamic
microphone with wide-range frequency re-
sponse making it an excellent
choice
for gen-
eral-purpose and office paging applications.
The US622L is a noise-cancelling dynamic
microphone designed for paging, dispatch-
ing and call systems in which background
noise is high or for reduction of feedback
under difficult acoustical conditions. The
US622L allows the user to speak closely into
the microphone in a normal voice, while
background noise is greatly
attenuated.
The
frequency response was designed to ensure
excellent intelligibility.
The rugged, diecast stand is carefully bal-
anced for handheld use as a "grip to talk"
microphone, yet will remain
firmly
posi-
tioned for "touch to talk" use. The
switch
assembly will survive many hundreds of
thousands of use cycles--assuring the ulti-
mate in reliability. The switch assembly may
be changed from "touch to talk" to
"grip
to
talk." The switch may be locked in the "on"
position for "hands free" operation. There is
an adjustment screw that permits the lock-
ing feature to be defeated. This control is
accessible only when the switch is located
in the "touch to talk" position.
Locking Feature
In the "touch to talk" position, the switch is
locked in the
"on"
position by depressing the
switch bar and sliding it to the right. If the
switch assembly is mounted in the "grip to
talk" position, the switch bar should be de-
pressed and slid upwards to lock. To unlock
the switch bar, reverse the procedure.
Defeating the Locking Feature
With the switch in the
"touch
to talk" con-
figuration, the locking feature may be de-
feated by an adjustment screw located
through the access hole in the bottom plate
(see Figure 5). Rotating the screw fully
clockwise defeats the locking feature. To de-
feat the switch locking feature in the "grip
to talk" configuration, the adjustment must
be made prior to moving the switch assem-
bly to the neck location. To restore the lock-
ing feature, tum the adjustment screw coun-
terclockwise until locking is now possible.
US621L
US622L
DYNAMIC DESKTOP
MICROPHONES
• Touch to talk
• 7-foot, 5-conductor cable with
bare-wire termination
• US621l: Omnidirectional
US622l: Cardioid,
noise-cancelling
Changing Switch Connections
The US621L and US622L are shipped with
switch connections as shown in Figure 6. The
microphones have shorted outputs in the
"off"
position. See Figure 6 for complete in-
structions.
The switch assembly is easily accessible for
wiring revisions. First, remove the bottom
cover plate, then remove the two switch as-
sembly screws to release the assembly for
easy access to switch terminals.
Parallel Operation
If the US621L and US622L are to be used in
applications such as multiple microphone
paging installations (where several units are
connected in parallel to a single microphone
input), changes must be made as shown in
Figure 6. Cutting the short wire "opens" the
microphone output when the switch is in the
"off"
position; this will allow multiple mi-
crophone applications.
Relocating Switch
The microphones are designed for "touch to
talk" or "grip to talk" operation. When re-
ceived from the factory, the switch is
mounted on the base for "touch to talk" use.
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