MFJ MFJ-817C - Calibration Procedure; Equipment and Test Setup; Forward Power Scale Calibration; Reflected Power Scale Calibration

MFJ-817C
Deluxe
VHF/UHF
True
Peak
Reading
SWR/Wattmeter
Instruction
Manual
Calibration
The
MFJ-817C
has
been
calibrated
at
the
factory.
If
it
should
ever
need
to
be
recalibrated,
then
follow
this
procedure:
Equipment Needed
1.
Transmitter
capable
of
supplying
enough
power
to
obtain
%
to
full-scale
reading
at 144/220/440
MHz.
2.
50-ohm
dummy
load
that
is
capable
of
handling
full
transmitter
output
power
and
has
better
than
a
1.15:1
SWR
at
144/220/440
MHz.
3.
Power
meter
of
know
accuracy.
The
calibration
will
only
be
as
good
as
the
standard
reference
meter.
4.
50-ohm
cables
capable
of
handling
the
power.
RG-58/u
is
recommended.
DO
NOT
USE
RG-59
or
RG-11.
Meter Calibration
1.
Refer
to
Figure
J
for
the
Test
Setup
and
refer
to
the
PCB
layout
in
Figure
2
for
trim
pot
location.
2. Remove the top of the MFJ-817C.
3.
Connect
the
Test
Setup
equipment
as
shown
in
Figure
/.
Use
a
50-ohm
dummy
load
for
the
antenna.
Set
the
Transmitter
to
the
144/220/440
MHz
in
the
VHF/UHF
band.
4.
With
the
300/30
Watts
button
pushed
in
for
the
300
Watt
scale,
Transmit
100
Watts
as
indicated
on
the
reference
meter.
Adjust
the
HI
FWD
trim
pot
to
set
the
forward
power
scale
to
100
Watts.
5.
With
the
300/30
Watts
button
pushed
out
for
the
30
Watt
scale,
Transmit
10
Watts
as
indicated
on
the
reference
meter.
Adjust
the
LO
FWD
trim
pot
to
set
the
forward
power
scale
to 10 Watts.
6.
To
set
the
reflected
power,
interchange
the
TRANSMITTER
and
ANTENNA
coax
cables
so
that
the
transmitter
is
connected
to
the
ANTENNA
connector
and
the
dummy
load
is
connected
to
the
TRANSMITTER
connector.
7.
With
the
300/30
Watts
button
pushed
in
for
the
60
Watt
reflected
scale,
Transmit
10
Watts
as
indicated
on
the
reference
meter.
Adjust
the
HI
REF
trim
pot
to
set
the reflected
power
scale to 10 Watts.