Lectrosonics UDR200b User Manual download pdf (Page 8)

REAR PANEL CONTROLS AND FUNCTIONS

AUDIO OUTPUT

A calibrated control on the rear panel adjusts the output level

in 5 dB steps, referenced in dBu. This control knob adjusts the

absolute output level at the XLR connector. The AUDIO OUT-

PUT level control is located after the output transformer. This

allows the signal to noise ratio to remain constant regardless

of the setting of the control. As the audio level is reduced, the

noise is also reduced maintaining the same ratio.

PHASE REV

This switch reverses the polarity of the audio output signal.

The "0" setting corresponds to a positive signal at the transmit-

ter input producing a positive output on pin 2 of the XLR audio

output connector.

AC POWER SUPPLIES

The UDR200B has a universal switching power supply which

will operate on AC voltages from 95 to 240 Volts, 50 or 60 Hz.

There is no external fuse since the power supply is self pro-

tected against line transients, short circuits, and over current

conditions.

EXT DC IN

The primary purpose of this jack is to provide battery backup

in case of a loss of normal AC power. The receiver will accept

power from this jack under two conditions. The first is when-

ever the front panel power switch is in the OFF position and

the second is when the front panel power switch is in the ON

position

and the normal AC power fails or is removed. This

jack can also be used to provide normal DC power to the

receiver, if desired, although the power switch OFF position

will not function as expected. When using this jack to provide

normal DC power the receiver will always be ON regardless of

the position of the front panel power switch.

The external DC source can be 12 to 26 VDC. Pin 4 is positive

and pin 1 is ground. This jack will accept a standard 4-pin

female XLR connector. The relays and power supply stage are

fully protected by automatic reset poly fuses. The ground side

of the power supply is protected with a self resetting poly fuse

in case the UDR200B is connected to a positive ground device

through the audio cabling. The poly fuse will trip to protect the

receiver and the offending ground path can then be removed.

LecNet (RS232) JACK

This 3.5mm stereo mini jack provides the serial connection

between the receiver and the computer. A stereo mini to DB9

cable is supplied with the receiver.

ANTENNA JACKS

These are standard 50 Ohm BNC terminals for the RF input to

the receiver.

EXPANSION OUT, EXPANSION IN

These miniature jacks provide the serial port interface for

multi-channel systems in a “daisy chain” manner. The receiver

that connects to the computer uses the IN jack to receive

signals and information from the OUT jack on the next receiver

in the chain.

See the interconnect diagram on the next page.

PILOT TONE BYPASS

This switch defeats the audio output muting and triggering

action of the pilot tone. When the pilot tone is bypassed, the

Opti-Blend and the Variable Cutoff Low Pass Filter will still

provide a squelching action during weak signal conditions.

These circuits will still provide approximately 50 dB of muting

when the pilot tone is bypassed. When bypassed, a warning

message is displayed on the front panel LED character strip.

NOISE FILTER

A sophisticated dynamic noise reduction filter can be switched

to operate in two different modes. The most effective mode is

the “TRI MODE DYNAMIC”. This mode derives a signal that is

proportional to the high frequency content of the desired audio

signal multiplied by the amplitude of the desired audio signal

and divided by the RF noise level. This derived signal controls

a proportional low pass noise filter that responds to transient

high frequency signals in less than a millisecond; this speed is

commonly accepted as much faster than the human ear can

resolve. Basically, the filter gets out of the way of high fre-

quency audio information so quickly that the ear cannot detect

its operation. In addition this filter reduces high frequency

room noise and also the electronic microphone noise that is

present to some extent in all small electret microphones.

It may sound as if the filter is dulling the sound but this is a

well known psycho acoustic effect of reducing high frequency

noise. The ear is sensitized or fooled by hiss to “hear” more

high frequencies. The second mode, “LOW RF ONLY”, oper-

ates the filter only when the RF link between transmitter and

receiver is unusually weak, less than 5uV at the receiver

antennas. This is a relatively rare circumstance and so the

noise filter is effectively out of the circuit except when abso-

lutely needed.

AUDIO OUTPUT

ANT B

PILOT

TONE

BYPASS

0 180

-0

-5

dBu

-10

-15

-20

-25

-30

-35

PHASE

ANT A

OUT

GND

LIFT

(RS232)

LecNet

EXPANSION

NOISE FILTER

TRI MODE

DYNAMIC

LOW RF

ONLY

90 - 240 VAC

EXT DC IN

+12 TO 26V

UDR200B Rear Panel

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 21 22

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Lectrosonics UDR200b User Manual Page 8

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