Lectrosonics T195 User Manual download pdf (Page 4)

The 195 system utilizes a separate ultrasonic tone modulation of the basic carrier to operate the receiver squelch. A

32kHz tone is injected into the audio signal after the microphone preamp, just after the compandor. The supersonic

pilot tone is filtered out of the audio signal immediately after the detector in the receiver so that it does not influence

the compandor or various gain stages. The basic benefit of the pilot tone squelch system is that the receiver will

remain squelched (muted) until it receives the pilot tone from the matching transmitter, even if a strong RF signal is

present on the carrier frequency of the system.

The high output antenna utilizes the lower half of the printed circuit boards as one radiating element, with the upper

half of the PC boards and mic capsule as the other half of the dipole configuration. This allows the mic to be held in

any position, since the user’s hands have little or no effect on the radiated power.

75kHz deviation improves the capture ratio, signal to noise ratio and AM rejection of a wireless system dramatically.

75kHz deviation is frequently used in the UHF spectrum, but it is much harder to implement at VHF frequencies. The

195 system is the first to take advantage of this wider deviation now allowed by the FCC in the VHF spectrum.

Almost all other VHF wireless systems use 15kHz deviation.

High efficiency circuits throughout the design allow over 4 hours of operation using a single 9 Volt alkaline battery

and 12 hours with a lithium battery. The battery compartment is a unique mechanical design which automatically

adjusts to fit any brand alkaline battery. Battery replacement is easily accomplished by releasing the bottom ring and

removing the battery cover. No tools are needed to change the battery. The battery is spring loaded to prevent

“rattle” as the unit is handled.

The VHF RF transmitter section is composed of a crystal stabilized main oscillator followed by a frequency tripler and

two frequency doublers. The UHF transmitter section uses a crystal stabilized main oscillator followed by quad/

double/double/double multiplier stages. The crystal controlled frequency is extremely stable over a wide temperature

range and over time. Double tuning used in the multiplier stages provides higher attenuation of spurious emissions

which, in turn, minimizes the possibility that the transmitter RF output would interfere with another transmitter/

receiver system operating in the same vicinity.

CONTROLS AND FUNCTIONS

EXTERNAL

“P” SWITCH – POWER ON/OFF

A slide switch which turns battery power on and off. The LED next to the switch lights up when the “P” switch is

When the battery

The LED will glow brightly when the battery is good

turned on. This LED also serves as a battery condition indicator.

and will dim as the battery condition deteriorates. The LED is at full brightness with a new battery.

voltage reaches 7 Volts, the LED will be completely dark.

Audio Power

On/Off On/Off

“A” SWITCH – AUDIO ON/OFF

A slide switch which “mutes” the audio in the OFF position and allows the audio gain (modulation level)

of the transmitter to be adjusted without feedback from the sound system.

INTERNAL

MOD LEVEL LEDs

These LEDs indicate the audio input level and are used when adjusting the transmitter AUDIO LEVEL (gain) control.

As the audio level increases, first one LED lights. The other LED lights as the audio level reaches maximum modula-

tion. The LEDs are located underneath the battery cover, next to the AUDIO LEVEL control and are easily viewed

when holding the transmitter in a normally used position.

Mod Level

AUDIO LEVEL

LEDs

This knob (located underneath the battery door) is operated while speaking or singing into

the transmitter to adjust the audio gain of the transmitter for the correct amount of modu-

lation. The LEDs located next to it indicate the modulation level as the gain is adjusted.

See page 6 for details on this very important adjustment.

AUDIO

LEVEL

Gain Control

1 2 3 4 5 6 7 8 9 10 11 12

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Lectrosonics T195 User Manual Page 4

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