LF Engineering L-202B User manual

L-202B VLF Preamplifier
The L-202B fixed tuned preamplifier is an
amplifier and filter combination designed to
improve your present receiver or converter's VLF
and LF reception.
The unique design with a sharp roll off filter
cleans up broadcast inter-modulation, reduces
noise, and boosts gain throughout the entire LF
spectrum. 10 kHz to 520 kHz broadband
coverage with adjustable gain eliminates the
need for an external antenna tuner. The L-202B is
designed for use with typical 50 foot SWL wire
antennas.
Features
Broadband
coverage, 10 kHz to
520 kHz
(no tuning
necessary)
Adjustable gain 28
dB max.
8 dBm max.
power output.
LED power
indicator.
Antenna returned to
the receiver in the
off position.
External 120 vac /
12 vdc supply
included.
L-202B Specifications
Size: 4.19"L x 2.74"W x 1.57"H
Filter Rejection: >40 dB in AM BC passband and higher
Gain: 28 dB maximum (adjustable)
Pass Band: 10 to 520 kHz +4 dB
Max. (linear) Output Power:8 dBm
Output Impedance: 50 - 75 ohms
Input Impedance: 2k ohms
Input/Output Jacks: RCA
DC Power: 12 - 15 vdc, 30 - 40 mA.
AC Power: 120 vac / 12 vdc external power pack
with 2.5 mm plug
L-202B VLF Preamplifier
Product Warranty
LF Engineering Co. warrants that, at the time of shipment the products
manufactured by LF Engineering Co. are free from defects in material and
workmanship. LF Engineering Co. obligation under this warranty is limited to
replacement or repair of such products within 1 year from the date of shipment.
For sales or return authorization, contact LF Engineering Co. at (860)
526-4759. For technical support call [phone].
LF Engineering E-mail address: [e-mail]
Copyright 2004 by LF Engineering Co.
All rights reserved.
Printed in U.S.A.
LF Engineering Co.
17 Jeffry Road
East Haven, CT 06513

Introduction:
The L-202B broadband VLF preamplifier is designed ideally for SWL long
wire antennas between 40 and 70 feet in length. A wide band linear
device is used to insure low noise and ample gain throughout the
spectrum.
The L-202B can be used to match long wire antennas to 50 ohm
converters and eliminates the need of an LF tuner.
Static discharge protection is provided at the (ANT) input for moderate
discharges (short of direct lightning strikes).
The 120 vac / 12 vdc power supply plugs into the
2.5 mm jack located on the front panel.
Installation:
Connect the VLF preamplifier (RCVR) RCA jack output to your existing
converter or LF receiver's input with coax or shielded cable. Connect your
receiving antenna to the (ANT) RCA jack input on the preamplifier.
Gain is factory set nominally at 8 dB. You can adjust this level with the
gain control located on the PC board. Use a small screwdriver or
alignment tool.
How to Get the Most Out Of Your L-202B VLF Preamplifier:
1. Front end overload and or inter-modulation caused by strong low
frequency signals, or use of an antenna greater than 100 feet can be
controlled by reducing the gain level on the L-202 and the RF gain
control on your receiver. A series tuned LC circuit in series with the
antenna at the input of the preamplifier will also help control overload.
2. Noise from light dimmers and other man made EMI will be reduced
using the L-202B. The factory adjusted gain setting is optimum when
using a 40 to 70 foot antenna.
3. Connect the antenna directly to the antenna input. Do not use long
lengths of grounded coaxial cable (6 feet or less).
RCA 2k ohm
Antenna Input
2.5mm
mono jack
12-15 vdc
RCA50ohm
Output to
Receiver
Trim Pot
adjustment
onPCboard
(inside)