MFJ-1020B Active Antenna Instruction Manual
MFJ-1020B Active Antenna
The MFJ-1020B Active Antenna provides reception of radio signals without an outside antenna.
The MFJ-1020B receives from 300KHz to 30MHz which includes all international short-wave
and high-frequency bands. This antenna also functions as a pre-selector for inside and outside
wire antennas through the use of FET and bipolar circuitry with a tuned input section. The tuned
circuit in the Active Antenna gives RF selectivity and reduces noise outside the tuned band. This
circuit can be bypassed without disconnecting the unit by using the On/Off Bypass switch. Use a
9V battery and the telescoping antenna for portable operation.
Installation
1. An optional MFJ-1312B AC adapter or a 9-12 Vdc power supply should be connected to the
power jack on the rear of the MFJ-1020B. The power jack accepts a 2.1mm coaxial plug
with the center conductor positive and the sleeve ground. A standard 9 volt battery can be
connected to the battery snap inside the cabinet for portable operation.
2. A shielded cable should be connected from an Output jack on the MFJ-1020B to the antenna
input on the receiver. Use either the RCA phono output or the SO-239 output depending on
the connector on your radio.
3. Connect the Gnd post on the MFJ-1020B to a good RF or earth ground, such as a metal cold-
water pipe or a metal rod driven into the earth. Proper grounding will help eliminate
oscillation that may occur.
4. The internal telescoping antenna should be fully extended prior to use. Do not connect an
external antenna when the internal antenna is extended.
5. If the unit is to be used as a pre-selector, use a shielded cable to connect your external
antenna to the Input jack on the rear of the MFJ-1020B and retract the internal antenna. Use
either the RCA phono input or the SO-239 input depending on the connector on your radio.
NOTE: Fluorescent lamps, electric motors, microwave ovens, televisions, and other electrical
or electronic devices can generate noise that may be picked up by the MFJ-1020B. The MFJ1020B should be located as for as possible from these devices or interfering devices should be
turned off while the MFJ-1020B is in use.
Front Panel Controls
On, Off/Bypass: Power is applied to the circuit when this switch is depressed. Signal from the
antenna are connected directly to the Output jack when the power is off.
Gain: This control adjusts the gain in the amplifier section of the Active Antenna.
Band: This control is used to select the tuning band for the desired frequency coverage.
Tune: This control adjusts the frequency of the tuned circuit within the selected tuning band.
The frequencies on the tuning dial are to assist in faster tuning. Proper tuning procedures
are described in the operation section.
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MFJ-1020B Active Antenna Instruction Manual
Operation
The On-Off switch should be depressed after the MFJ-1020B is properly connected. The LED
will light, indicating circuit operation. Set the Band control to the desired tuning range.
The Tune control scale is used as a guide. Set the Tune control to the same frequency as your
radio. Adjust Tune for maximum signal strength with the receiver's tuning meter or for the
clearest audio.
Note: The Tune control may be inadvertently set to a receiver image or to a strong undesired
signal. In the presence of such signals the receiver may overload. In this case best circuit
operation may be achieved at less than the maximum Gain setting.
Oscillation may occur at some frequencies if Gain is set too high. This type of oscillation is
particularly common with portable receivers using plastic cabinets. Oscillations may be
recognized by one or more of the following symptoms:
1. Unmodulated carriers are noticeable when tuning through a frequency range with the
Tune control on the Active Antenna.
2. When the MFJ-1020B Tune control is adjusted, different stations appear and disappear as
if the radio is being tuned.
3. Stations other than the desired station appear.
If this happens, connect a ground wire from the ground post of the MFJ-1020B to a ground post,
a jack, or the telescopic antenna on the receiver.
NOTE: External antennas should be disconnected from the input jack when operating the
MFJ-1020B with it's internal antenna. The MFJ-1020B Tune dial may be slightly less
accurate when operating with an external antenna.
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MFJ-1020B Active Antenna Instruction Manual
FULL 12 MONTH WARRANTY
MFJ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ Enterprises,
Inc. and purchased from an authorized dealer or directly from MFJ Enterprises, Inc. to be free from
defects in material and workmanship for a period of 12 months from date of purchase provided the
following terms of this warranty are satisfied.
1. The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check, credit card or
money order receipt, etc.) describing the product to establish the validity of the warranty claim
and submit the original of machine reproduction or such proof of purchase to MFJ Enterprises,
Inc. at the time of warranty service. MFJ Enterprises, Inc. shall have the discretion to deny
warranty without dated proof-of-purchase. Any evidence of alteration, erasure, or forgery shall be
cause to void any and all warranty terms immediately.
2. MFJ Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to the original
owner any defective product under warrantee provided the product is returned postage prepaid to
MFJ Enterprises, Inc. with a personal check, cashiers check, or money order for $7.00 covering
postage and handling.
3. MFJ Enterprises, Inc. will supply replacement parts free of charge for any MFJ product under
warranty upon request. A dated proof of purchase and a $5.00 personal check, cashiers check, or
money order must be provided to cover postage and handling.
4. This warranty is NOT void for owners who attempt to repair defective units. Technical
consultation is available by calling (601) 323-5869.
5. This warranty does not apply to kits sold by or manufactured by MFJ Enterprises, Inc.
6. Wired and tested PC board products are covered by this warranty provided only the wired and
tested PC board product is returned. Wired and tested PC boards installed in the owner's
cabinet or connected to switches, jacks, or cables, etc. sent to MFJ Enterprises, Inc. will be
returned at the owner's expense unrepaired.
7. Under no circumstances is MFJ Enterprises, Inc. liable for consequential damages to person or
property by the use of any MFJ products.
8. Out-of-Warranty Service: MFJ Enterprises, Inc. will repair any out-of-warranty product
provided the unit is shipped prepaid. All repaired units will be shipped COD to the owner.
Repair charges will be added to the COD fee unless other arrangements are made.
9. This warranty is given in lieu of any other warranty expressed or implied.
10. MFJ Enterprises, Inc. reserves the right to make changes or improvements in design or
manufacture without incurring any obligation to install such changes upon any of the products
previously manufactured.
11. All MFJ products to be serviced in-warranty or out-of-warranty should be addressed to
MFJ Enterprises, Inc., 300 Industrial Park Road, Starkville, Mississippi 39759, USA and
must be accompanied by a letter describing the problem in detail along with a copy of your dated
proof-of-purchase.
12. This warranty gives you specific rights, and you may also have other rights which vary from state
to state.
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