Handbook for Sound Engineers

1540 Chapter 41

41.4.2. FM Receiver

A typical FM receiver is shown in Fig. 41-12. The spec-
ifications for this FM receiver are:

General

• Number of channels: 19 wide band, 38 narrow band.


• SNR: 70 dB or greater.


• Programmable to electronically lock out unneeded
  channels.


• Can seek channels and can be locked on a single
  channel.


• Adjustable squelch.


• Audio frequency response: 50 Hz–15 KHz ±3 dB.


• Includes: a stereo headset jack for either a mono or
  stereo headset.


• Includes: an LCD display that indicates channel,
  battery level, low battery, battery charging, and RF
  signal strength.


• Functions in both DX and Local mode.


• Operates on two AA batteries.


• Includes: an automatic battery charging circuitry for
  recharging of NiMH batteries.

Radio Frequency

• RF frequency range: 216.0125–216.9875 MHz.


• Number of channels: 19 wide band, 38 narrow band.


• Sensitivity: 0.6 uV typical, 1 uV maximum for 12 dB
  sinad.


• Frequency accuracy: ±0.005 stability, 32 to 122qF.


• Antenna: uses earphone cable.


• Squelch: programmable in twenty steps, automatic on
  loss of RF signal.


• Compliance: FCC Part 90, Industry Canada.

Audio

• Frequency response: 50 Hz–10 kHz ±3 dB 216 MHz.


• SNR (A-weighted): SQ enabled: 80 dB; SQ disabled
  60 dB.


• System distortion: <2% total harmonic distortion
  (THD) at 80% deviation.


• Output: unbalanced, 0 dBu nominal output level,
  16 mW maximum, impedance 32:.

Controls

• User controls: channel up/down, seek, volume.


• Set up controls (battery compartment): alka-
  line/NiMH batteries, SQ enable/disable.


• Programming: channel lock, squelch, channel lock-
  out.

Indicators

• Red LED: illuminated when unit is on. Flashes when
  batteries are low, or to indicate charging. Flashes
  when locked and seek is pushed.


• Display: channel designation, lock status, signal
  strength indication, programming.

Power

• Battery type: two AA batteries, alkaline or NiMH.


• Battery life: alkaline–15 h NiMH rechargeable.


• Battery charging (NiMH only): fully automatic, 14 h.


• Power supply: Input—120 Vac, Output—7.5 Vdc
  250 mA.
  Physical


• Dimensions (H × W × D) 5.0 × 3.0 × 1.0 inches
  (13.0 × 7.6 × 2.5 cm).


• Color: dark gray with white silk screening.


• Unit weight: 3.9 oz (111 g).


• Unit weight with batteries: 5.8 oz (164 g).
  The above specifications are fairly common for
  high-quality receivers.

41.4.3. All-in-One System

An all-in-one system or self-contained system for use in

multiple venues is Listen Technologies’ Soundfield FM,

Figure 41-12. Typical high-quality FM receiver, the Listen

LR-500-863. Courtesy Listen Technologies Corporation.