Lectrosonics REFUM User Manual

REFUM/REFSWITCH

Referee Transmitter and Switch

• Externally switched “no pop” audio muting

• Digital Hybrid Wireless™

(U.S. Patent 7,225,135)

• Compatible with older Lectrosonics

analog receivers

• 256 synthesized UHF frequencies and

100 mW output power

• Adjustable low frequency roll-off

• Rugged machined aluminum construction
A Complete System Includes:

• REFUM transmitter

• REFSWITCH external mute with

Interface cable

• M152 or other electret microphone

Digital Hybrid WirelessTM is a revolutionary new

design that combines digital audio with an analog
FM radio link to provide outstanding audio qual­ity and the extended operating range of the finest
analog wireless systems. The design eliminates the
audio companding process.

The design overcomes channel noise in a dramati­cally new way, digitally encoding the audio in the
transmitter and decoding it in the receiver, yet still
sending the encoded information via an analog FM
wireless link. This proprietary algorithm is not a
digital implementation of an analog compandor. In­stead, it is a technique which can be accomplished
only in the digital domain, even though the audio
inputs and outputs are analog signals.

US Patent No. 7,225,135

The referee transmitter offers sports officials the latest
digital/analog hybrid technology in a convenient, weather­resistant package. Using the REFSWITCH external belt­pack switch assembly, the audio in the REFUM transmit­ter can be muted or engaged, without pops or clicks in the
audio.

A 5-pin input jack provides taps for low impedance
dynamic mics, electret lavalier mics (positive or nega­tive bias) and a pin designated for audio muting using
an external switch. Input gain is adjustable over a 43 dB
range to perfectly match the audio input level for optimum
modulation, minimum distortion and maximum signal to
noise ratio. Input levels are accurately indicated by two
LEDs on the control panel.

The input is gain controlled with a wide range dual enve­lope input limiter, which cleanly limits input signal peaks
over 30 dB above full modulation. Along with the Digital
Hybrid Wireless™ audio path, the RF transmission is an
aggressively optimized FM system with +/- 75 kHz wide
deviation for a high signal to noise ratio. The overall sys­tem delivers full bandwidth audio frequency response up
to 20 kHz plus excellent operating range and resistance
to interference.

The REFUM is powered by a single 9 V battery and
provides a full 100 mW output for extended operating
range. The housing and belt-clip are machined aluminum,
powder coated and laser engraved for ruggedness and
legibility.

TECHNICAL DATA

Rio Rancho, NM, USA

www.lectrosonics.com

REFUM TRANSMITTER

581 Laser Road NE • Rio Rancho, NM 87124 USA • www.lectrosonics.com
[phone] • [phone] • fax [phone] • [e-mail]

The low frequency roll-off

is adjustable from 35

Hz to 150 Hz to control

the presence of low

frequency audio in the

program material.

Easy to reach

ON/OFF switch

handle

The machined

aluminum battery

door is hinged to the

housing. Battery

contacts automatically

adjust to a wide variety

of alkaline and lithium

9 V batteries.

Reversible Belt Clip

REFSWITCH

Rugged machined aluminum housing

and spring loaded belt clip

Transmitter and

Microphone

Jacks

Specifications

Operating Frequencies (MHz); Block 21 537.600 - 563.100

Frequency selection: 256 frequencies in 100kHz steps

Channel Separation: 100 kHz

RF Power output: 100 mW

Pilot tone: 25 to 32 kHz; 5kHz deviation

Frequency stability: ± 0.002%

Deviation: ± 75 kHz (max)

Spurious radiation: 90 dB below carrier

Equivalent input noise: –120 dBV (A-weighted)

Input level: Nominal 2 mV to 300 mV, before limiting.

Input impedance: Taps provided for 200, 4k, 40k Ohm

Input limiter: Dual envelope “soft” limiter; greater than

Gain control range: 43 dB; semi-log rotary control

Modulation indicators: Dual bicolor LEDs indicate modulation of

Audio Performance (overall system):

Frequency Response: 32 Hz to 20 kHz (+/-1dB)

Low freq. roll-off adjustment: –18 dB/octave; adjustable from

Block 25 640.000 - 665.500

Greater than 1V maximum, with limiting.

30 dB range

-20, -10, 0 and +10dB referenced to full
modulation

35Hz to 150Hz

SNR at receiver output:

(Note: The dual envelope “soft”
limiter provides exceptionally
good handling of transients using
variable attack and release time
constants. The gradual onset of limiting in the design begins below clipping level, which
reduces the measured figure for SNR without limiting by 4.5 dB)

THD: 0.2% (typical)

Input Dynamic Range: 125 dB (with full Tx limiting)

Controls: Two position “ON-OFF” power switch

Audio Input Jack: Switchcraft 5 pin locking (TA5F)

Antenna: Detachable, flexible wire supplied; 50 Ohm port

Battery: Precision compartment auto-adjusts to accept any

Battery Life: 5 hours (alkaline); 10 hours (lithium)

Weight: 6.98 ozs. - 198 grams (including lithium 9V battery

Dimensions: 3.17 x 2.48 x .84 inches

Emission Designator: 180KF3E

SmartNR No Limiting W/ Limiting

OFF 103.5 108.0

NORMAL 107.0 111.5

FULL

Audio input gain knob

Low rolloff pot on side panel

Two 16-position rotary switches adjust
transmitter frequency

Audio muting from pin 5 on mic connector

allows connection to test equipment

known alkaline 9 Volt battery. (We’ve tried 243
different ones.)

and antenna)

108.5

113.0

February 2, 2006