MFJ Enterprises MFJ-722B User manual

MEJ
MEJ Optimizer
Model MFJ-722B
(ees
see
INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
VERSION 1A COPYRIGHT © 2012 MFJ ENTERPRISES, INC.

Specifications
Notch
Frequency Range 300-3000 Hz
Depth 70 dB
High Pass
Roll off below 375 Hz at 12 dB per Octave
SSB
Low Pass of 2.5 KHz, 2KHz, or 1.5 KHz
cw
Center Frequency aprox. 790 Hz
3 dB Width of 180, 150, 110, 80 Hz
Audio Output 2W,
Power Supply 9-18VDC

MFJ-722B INSTRUCTIONS
INTRODUCTION
The MFJ-722B OPTIMIZER
consists of a tunable notch filter
combined with a — switch
selectable highpass/lowpass filter
(SSB) and bandpass (CW) filter.
This filtering capability allows
you to remove interference from
both SSB and CW signals thereby
optimizing the desired signal.
INSTALLATION
1, Connect any 9-18 VDC, 300
ma power supply to the POWER
jack on the rear of the MFJ722B.
‘An optional AC adapter (MFJ-
1312B) is available from MFJ
Enterprises, Inc. Use a 2.1 mm
Coaxial plug with the Center pin
positive. A 12 VDC, 300 ma
power supply is required for
maximum audio power output.
2. Connect a 4 to 16 ohm speaker
to the SPEAKER jack or connect
a set of stereo headphones to the
PHONE jack on the rear of the
MFJ-722B. 3. Connect a shielded
lead, with the proper connector,
from the external speaker or
headphone jack of your receiver
or transceiver to the INPUT jack
on the rear of the MFJ-722B. The
INPUT jack accepts an RCA
phono plug.
CONTROLS
ON-OFF/BYPASS SWITCH:
When depressed, power is
applied to the circuit as indicated
by the front panel LED. When
out, power is removed from the
circuit and the input signal is
switched directly to the
SPEAKER and PHONE jacks.
The filter circuit is bypassed.
NOTCH:
Only the notch filter in the MFJ-
722B affects the signal in this
switch position. NOTE: The
notch filter is operable in all other
SELECTIVITY switch positions
except BYPASS.
NOTCH FREQ: Varies the
frequency of the notch filter
section from 300 Hz to 3000 Hz.
NOTCH WIDTH: This control
allows adjustment of the
bandwidth of the notch filter
section only. Wide bandwidth
tuning is easy but removes a
larger slice of signal.

SELECTIVITY:
SSB MODE:
HP- The notch filter is followed
by a highpass filter which passes
all frequencies above 375 Hz.
Frequencies below 375 Hz are
rejected at the rate of 12
db/octave. This position greatly
reduces 60 Hz and 120 Hz hum
and other low frequency noise
and interference.
CW MODE:
The center frequency of the CW
filters is approximately 800 Hz.
The signal level peaks when you
tune the signal to this tone. Low
Q stages are used for minimum
ringing.
180- A single stage, 2 pole active
bandpass filter is selected with a
3 db bandwidth of approximately
180 Hz. This position is useful
for light QRM levels.
150- A two-stage active filter is
selected. This position is useful
for moderate to heavy QRM
levels.
BYPASS:
All filter sections of the MFJ-722
are bypassed and the signal is fed
directly to the output amplifier
circuit. The circuit is designed to
2.5- The HP filter is followed by
a lowpass filter that rejects
frequencies above 2.5 KHz.
2.0- The 2.5 KHz filter is
followed by another lowpass
filter to give a cutoff frequency of
2.0 KHz.
1.5- The 2.0 KHz filter is
followed by another lowpass
filter to give a cutoff frequency of
1.5 KHz.
110- The steeper skirts of three
active bandpass filter stages are
selected. This position is useful
for moderate to heavy QRM
levels.
80- Four active filter stages are
selected for a very narrow
bandwidth and very steep skirts.
You must be careful to tune
slowly while switching to this
position. Slight retuning may be
needed due to drifting of your
receiver and/or the transmitting
station. This position is useful for
heavy QRM levels.
supply a signal to the output
which is virtually the same as the
unfiltered input.
GENERAL OPERATIONS:
After connection as described in
the INSTALLATION section, the
MFJ-722B is ready for use.
The NOTCH filter in the MFJ-
722B is useful for removing
interfering signals near the
desired signal such _—as
heterodynes, stations tuning up
on your QSO, or CW signals near
frequency. Care should be taken

that the NOTCH WIDTH control
is not set to high or too low. If set
too low, the bandwidth is so large
the notch filter —_ appears
inoperable. If set too high, the
bandwidth is so narrow that the
NOTCH tuning is very critical
and the notch frequency is hard to
locate. Set the SELECTIVITY
switch to the NOTCH position.
After tuning in the desired signal
on your receiver, adjust the
NOTCH FREQ control to
attenuate unwanted signals near
the tuned signal.
The SSB positions of the
SELECTIVITY switch optimizes
the desired signal by attenuating
unwanted high or_~—— low
frequencies. In the HP position,
frequencies below approximately
375 Hz are attenuated reducing
interference such as 60 Hz and
120 Hz hum. In the 2.5, 2.0, and
1.5 position, a lowpass filter is
activated in addition to the
highpass filter. The range of
frequencies passed to the speaker
or headphones is progressively
narrower as the switch is changed
from 2.5 to 2.0 to 1.5. Only those
frequencies above the HP cutoff
frequency of 375 Hz and below
the selected lowpass cutoff
frequency are passed.
In the cw positions
SELECTIVITY switch, the
bandpass filters of switchable
bandwidth are activated. The 3 db
bandwidth is as set by the
SELECTIVITY switch at either
180 Hz, 150 Hz, 110 Hz, or 80
Hz. At the 80 Hz position, the
selectivity is so great that you
may notice a "talking in a barrel"
or slight ringing effect. This is
normal for this position. NOTE:
1) Be aware that the notch filter is
operable at all SELECTIVITY
switch settings except BYPASS.
If you do not desire the notch
function while using the SSB or
CW switch positions, rotate the
NOTCH FREQ control fully
clockwise to minimize the notch
filter effect.

FULL 12-MONTH WARRANTY
MFI Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFI
Enterprises, Inc. and purchased from an authorized dealer or directly from MEI 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 or machine reproduction of such proof of purchase to
MEI Enterprises, Inc. at the time of warranty service. MFI Enterprises, Inc. shall have the
discretion to deny warranty without dated proof-of-purchase. Any evidence of alteration,
erasure, of forgery shall be cause to void any and all warranty terms immediately
2. MFI Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to
the original owner any defective product provided the product is returned postage prepaid to
MFI Enterprises, Inc. with a personal check, cashiers check, or money order for $12.00 covering
postage and handling.
3. MFI Enterprises, Inc. will supply replacement parts free of charge for any MFI
product under warranty upon request. A dated proof of purchase and a $8.00 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 [phone].
3. ‘This warranty does not apply to kits sold by or manufactured by MFJ Enterprises,
Ine.
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 un-repaired.
7 Under no circumstances is MFI 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 licu of any other warranty expressed or implied
10, MFI 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
ul All MFS products to be serviced in-warranty or out-of-warranty should be addressed
to MFJ Enterprises, Inc., 300 Industrial Park Rd, 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 and a telephone number.
12 This warranty gives you specific rights, and you may also have other rights, which
vary from state to state
Rev 04/08/2011

MFJ ENTERPRISES, INC. 473-7225 Manual
300
Industrial
Park
Road
Version
1A
Starkville,
MS
39759
Printed
In
U.S.A.