MFJ MFJ-802B User manual

ME)
Field Strength Meter
Model MFJ-802B
INSTRUCTION MANUAL
CAUTION:
Read
All
Instructions
Before
Operating
Equipment
MFJ
ENTERPRISES,
INC.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
COPYRIGHT
@
1099
MFJ
ENTERPRISES,
INC.

MFJ-802B Instruction Manual
INTRODUCTION
Thank
you
for
purchasing
the
MFJ-802B.
A
field-strength
meter
(or
FSM)
is
one
of
the
most
practical
pieces
of
ham
test
equipment
you
can
own,
and
the
MFJ-802B
has
some
special
features
we
think
you'll
like,
For
example,
it
has
a
huge
high-resolution
meter
with
a
robust
0-
100
scale
that's
easy
to
read
from
several
feet
away.
It
also
combines
a
balanced
pick-up
antenna
with
a
RF-insulated
enclosure
to
eliminate
hand-capacitance
errors
typical
of
older-style
meters.
There's
a
high-Z
balanced
decoupling
network
that
ensures
top
efficiency
over
a
wide
frequency
range
and
provides
complete
isolation
between
the
detector
and
metering
circuits.
And,
there's.a
uA-type
meter
movement
with
a
wide-range
sensitivity
control
to
handle
signals
from
the
milliwatt
to
kilowatt
level.
Add
the
MFJ-802R
remote
pickup,
and
you
can
monitor
field
strength
from
anywhere
you
wish
in
the
comfort
of
your
shack.
Inexpensive
low-voltage
de
wire
connect
the
two
units
together.
Like
most
field-strength
meters,
the
MFJ-802B
is
extremely
simple
to
operate.
However,
as
with
any
piece
of
RF
test
equipment,
it
has
limitations
you
should
know
about--and
we
urge
you
to
read
the
manual
carefully
before
using
it.
YOUR
METER'S
CONTROLS
= Remote Sensitivity
O-5
. MFJ-802 FSM
1.
Collapsible
Dipole:
Balanced
pickup
element
extend
to
38"
(1/2-
wave
on
2-meters).
Adjust
for
resonance
at
VHF/UHF
frequencies,
or
extend
fully
and
use
as
a
non-resonant
dipole
at
HF.
The
antenna
is
RF-decoupled
from
metering
circuitry,
and
a
dipole
pattern
will
be
maintained
at
non-resonant
frequencies.

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MF/J-802B Instruction Manual
2,
Easy-to-Read
Meter
Scale:
Bold
0-100
scale
is
readable
for
several
feet--may
be
set
up
at
any
convenient
location
near
your
operating
site.
High-quality
meter
movement
resolves
even
small
changes
in
the
RF
field.
3.
Remote
Detector
Jack:
Standard
phone
jack
accepts
monaural
1/4"
plug
when
MFJ-802R
remote
detector
is
used.
4,
Wide-Range
Sensitivity
Control:
Adjusts
your
meter
for
a
wide
range
of
power
levels
and
distances
to
the
RF
source.
To
prevent
damage,
always
begin
measurements
with
the
sensitivity
control
set
at
minimum
(fully
counter
clockwise).
USING YOUR METER
The
MFJ-802B
is
useful
anywhere
a
hand-held
or
stationary
field-
strength
meter
is
needed.
For
example,
it's
perfect
for
resonating
critical
HF
mobile
antennas,
adjusting
tuning
networks,
optimizing
antenna
arrays
for
highest
ERP,
and
tuning
transmitter
circuitry
for
maximum
output.
Remember
to
exercise
caution
when
working
near
guises
antennas.
and permanent injury.
Here
are
some
specific
tips
to
help
you
get
the
most
from
your
meter:
1.
To
avoid
violently
pinning
the
meter,
always
begin
field-strength
measurements
with
the
sensitivity
control
turned
fully
down
(or
counter-clockwise).
Also,
it's
a
good
practice
to
store
your
meter
with
the
sensitivity
set
to
minimum.
2.
For
best
meter
resolution,
set
the
meter's
sensitivity
control
to
yield
mid-range
readings.
3.
Orient
the
meter's
pick-up
dipole
to
the
same
polarization
as
your
antenna
under
test.
4.
At
VHF/UHF
frequencies,
maintain
a
minimum
of
2-3
wavelengths
spacing
between
the
pick-up
antenna
and
any
antenna
under
test.
Closer
proximity
could
easily
damage
the
meter's
diode
detector,
and
may
detune
the
test
antenna
you're
attempting
to
adjust.

MFJ-802B Instruction Manual
5. Try to keep test antennas--and your meter's pick-up antenna--well
separated from nearby cables, masts, or other metallic structures
that could act as a parasitic element and effect your results.
may result:
REMOTE PICKUP (MFJ-802R)
The MFJ-802R is an optional antenna/detector unit that is identical to
your MFJ-802B--minus the meter and sensitivity control. The MFJ-
802R can be plugged into your primary meter and located remotely to
provide optimum monitoring positioning. For example, to obtain
station antenna measurements uncolored by household wiring and RF
leakage, install the MFJ-802R remote outside of the building and
connect it to your MFJ-802B in the ham shack. Or, for accurate-
antenna range measurements, install the MFJ-802R remote several
wavelengths down-range and locate the MFJ-802B meter at your
antenna test site. The MFJ-802B meter and remote pickup require
only low-cost 2-conductor dc wire for interconnection. The remote
pickup is a great way to increase the versatility and usefulness of your
MFJ-802B.
THEORY OF OPERATION
The MFJ-802B Field-Strength Meter uses a dipole sense antenna with
a diode bridge connected across its feedpoint. The diode bridge passes
dc-detector voltage to sensitivity control R1, while blocking RF and
isolating the antenna from common-mode pickup. R1 is an adjustable
voltage divider that controls the detector output level applied to meter
Ml. The remote detector is identical to the MFJ-802B, minus the
sensitivity contro] and meter.

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MFJ-802B Instruction Manual
IN CASE OF DIFFICULTY
Your
meter
has
no
internal
adjustments
and
represents
a
trouble-free
design.
However,
it
has
a
sensitive
electro-mechanical
meter
that
may
sustain
damage
if
dropped.
Also,
the
MFJ-802B
is
not
weatherproof,
and
should
not
be
exposed
to
heavy
rain,
snow,
or
other
harsh
environmental
conditions
TECHNICAL ASSISTANCE
If
you
have
any
problem
with
this
unit
first
check
the
appropriate
section
of
this
manual.
If
the
manual
does
not
reference
your
problem
or
your
problem
is
not
solved
by
reading
the
manual
you
may
call
MFI
Technical
Service
at
662-323-0549
or
the
MFJ
Factory
at
662-323-
5869,
You
will
be
best
helped
if
you
have your
unit,
manual
and
all
information
on
your
station
handy
so
you
can
answer
any
questions
the
technicians
may
ask.
You
can
also
send
questions
by
mail
to
MFJ
Enterprises,
Inc.,
300
Industrial
Park
Road,
Starkville,
MS
39759;
by
Fax
to
662-323-6551,
or
by
email
to
[email protected].
Send
a
complete
description
of
your
problem,
an
explanation
of
exactly
how
you
are
using
your
unit,
and
a
complete
description
of
your
station.

MEFJ-802B Instruction Manual
SCHEMATIC
UNLESS OTHERMISE SPECIFIED
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FIELD STRENGTH METER

LIMITED 12 MONTH WARRANTY
MF Enterprises, Inc. warrants to the original owner of this product, if manufactured by
MF] 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,
10.
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 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 shal] be cause to void any and all warranty terms
immediately.
. MFYJ 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.
This warranty is NOT void for owners who attempt to repair defective units. Technical
consultation is available by calling Service Department at 662-323-0549 or the MFJ Factory
at 662-323-5869.
This warranty does not apply to kits sold by or manufactured by MFJ Enterprises, Inc.
Wired and tested PC board products are covered by this warranty provided only the wired
and tested PC board product is retumed. 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 retuned at the owner's expense unrepaired.
Under no circumstances is MFJ Enterprises, Inc. liable for consequential damages to person
or property by the use of any MFJ products.
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.
This warranty is given in lieu of any other warranty expressed or implied.
MF] 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.
All MFJ products to be serviced in-warranty or out-of-warranty should be addressed to:
MEJ 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.
This warranty gives you specific rights, and you may also have other rights which vary from
state to state.