Listen Technologies LA-140, Design Manual

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LA-140
LT-82
Design Guide Design Guide
LR-42/44
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The IR stethoscope receiver shall be capable of receiving on four carriers (2.3, 2.8, 3.3, 3.8
MHz) and the channel shall be displayed on one of four front panel LEDs. The receiver shall
be capable of being locked on a channel. The receiver shall be capable of receiving a
stereo signal on each of the four carriers. The receiver shall have a SNR of 60 db or greater
and have built in squelch control. The device shall have an audio frequency response of
63 Hz to 15 kHz, +/- 3db and shall have distortion of less than 2%. The device shall operate
for 30 hours with two AAA alkaline batteries and 15 hours with two AAA NiMH rechargeable
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Specifications LR-42
RF
Carrier Frequencies Selectable: 2.3 MHz, 2.8 MHz, 3.3 MHz, 3.8 MHz
Number of Channels Four (4) selectable channels
IR Detectors Two (2) detectors under front IR lens
Sensitivity One (1) nW/cm2 at 40 db SNR
Frequency Accuracy +/- .005% stability 0 to 50C
Squelch Automatic on loss of RF signal (40 db SNR)
Compliance FCC Part 15, Industry Canada, CE, RoHS
Audio
** All system specifications are wireless end-to-end
System Frequency Response 63Hz - 15kHz (+/- 3dB)
System Signal to Noise Ratio
(A-weighted)
Mono: >60dB
Stereo: >52dB
System Distortion <2% total harmonic distortion (THD)
Audio Output Jacks 3.5 mm connector unbalanced, mono or stereo headphones
Audio Output Power 20 mW maximum at 32 ohms
Controls
User Controls Volume, Power, Channel Select
Programming Channel Lock, Auto Seek, Channel Lock-Out, Squelch
Indicators
Unit Power Indicated by current channel selection LED
Channel Selection Red LED illuminates on the current channel selection
Power
Battery Type Two (2) AAA alkaline batteries or NiMH battery pack
Battery Life 30 hours alkaline, 15 hours NiMH rechargeable pack
(LA-364)
Battery Charging Fully Automatic with NiMH battery pack and LA-350 charger
Physical
Dimensions (H x W x D) 1.8 x 4.0 x .75 in (46x102x19 mm) Stethoscope Arm length 8 in (203 mm)
Color Grey with White Silk Screening
Unit Weight without batteries 1.75 oz. (49 g)
Unit Weight with batteries 2.55 oz. (74 g)
Shipping Weight 8.00 oz. (227 grams)
Environmental
Temperature - Operation -10 C (14 F) to +40 (104 F)
Temperature - Storage -20 C (-4 F) to +50 (122 F)
Humidity 0 to 95% relative humidity, non-condensing
•Specifications are subject to change without notification.