5
Plug-On Transmitter
Rio Rancho, NM – USA
CONTROLS AND FUNCTIONS
The H175DC may be used with a wide variety of microphones. The 3-pin XLR type connector on the H175DC allows
the transmitter to be used with any dynamic microphone, as well as many two wire positive bias lavalier systems
(such as those systems supplied by Lectrosonics.)
INPUT JACK
Standard 3-pin XLR type. Pin 2 is signal, pin
3 is signal ground, and pin 1 is case ground
(see schematic in Figure 2.) The H175DC
locks onto a standard microphone. The XLR
connector is permanently bonded to the to
the locking assembly, and is not normally
replaceable. The electret bias is 5 Volts at
1mA or less. The bias is connected in a
“phantom” manner and will not interfere with
any standard balanced microphone. If severe noise is experienced when the microphone is moved with respect to
the H175, the cause is an unbalanced condition between pins 2 and 3 of the microphone.
POWER OFF/ON
Turns the battery power on and off.
BATTERY POWER LED
Glows brightly when battery is good. A weak or dim power LED means that the battery is weak, and has about an
hour of operation left. If the LED fails to light, the battery should be replaced. The POWER LED is connected to a
precision battery test circuit that continuously monitors battery voltage. The LED is at full brightness with a new 9 Volt
alkaline. As the battery voltage drops during use, the LED brightness will also decrease. After 12 to 15 hours the
battery voltage will be about 7 Volts. The LED will be completely extinguished. Since the internal circuits are all
tightly regulated and the RF output stage has a separate discrete regulator, the transmitter will continue to operate to
a battery voltage of 6.5 Volts. From 6.5 Volts to 6 Volts, the transmitter will still operate, but with degraded perfor-
mance. Please note that a weak battery will sometimes light the POWER LED immediately after turn on, but soon
will discharge to the point where the LED will extinguish.
The combination of an accurate battery condition indicator and regulation of all internal circuits guarantees much
longer battery life, as well as consistent performance versus battery life.
LEVEL CONTROL
Used to adjust the audio input volume for the proper modulation level. Rotate knob until the LEVEL LED on the
receiver flickers when there is an input signal. The LIMIT LED on the receiver should light occasionally.
1 UH
1 UH
1 UH
1K
1K
980
+9 VOLTS
1
2
3
33UF
5.1V
+
TO MIC PREAMP
AUTO-LOCK
XLR INPUT
TOP VIEW
CONTROL PANEL
ON
OFF
LEVEL
BATTERY
POWER
LED
1
2
3
(Note: The H175DC, Digital Code Squelch version is operationally identical to the standard H175.)
Содержание H175DC
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