DRAKE W-4 User manual

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rs INSTRUCTION MANUAL
RL L. DRAKE COMPANY Miamisburg, Ohio U. S. A.

E>) DRAKE
GENERAL
DESCRIPTION.
The
DRAKE
Model
W—4
Wattmeter
is
a
through
line
wattmeter
which
accurately
measures
forward
and
reverse
power.
The
RF
coupler
is
made
removable
so
that
it
may
be
conveniently
located
at
the
output
of
the
transmitter.
SPECIFICATIONS
FREQUENCY
COVERAGE.
1.8
-
54
MHz.
LINE
IMPEDANCE.
50
Ohms
resistance.
ACCURACY.
Wattmeter
accuracy
is
+
(5%
of
reading
+
2
Watts)
on
200
Watts
scale,
and
+
(5%
of
reading
+
20
Watts}
on
2000
Watt
scale
throughout
the
range
of
1.8
-
54
MHz.
VSWR
INSERTION,
Insertion
of
wattmeter
in
line
changes
VSWR
no
more
thai
1.05:1.
POWER
CAPABILITY.
2000
Watts
RF
continuous
duty,
CONTROLS AND JACKS
FRONT
PANEL.
Range
Selector
Switch.
REMOVABLE
COUPLER.
Two
input
and
output
connectors
(SO
239),
Four
range
calibration
potentiometers.
One
.5
to
5
pf
piston
trimmer
null
adjustment.
DIMENSIONS
MAIN
CABINET.
6”
high,
3-11/16"
wide,
4”
cabinet
depth,
5”
overall length.
REMOVABLE CO
deep.
TT
UPLER.
2-1/2"
high,
3-3/8"
wide,
2-3/4”
AAROM 107K 1
Bors:

UNPACKING.
Carefully
remove
the
unit
from
=
the
shipping
carton,
and
examine
it
for
evidence
of
damage.
If
any
damage
is
discovered,
immediately
notify
the
transportation
company
that
delivered
the
unit.
Be
sure
to
keep
the
shipping
carton
and
packing
material,
as
the
transportation
company
will
want
to
examine
them
if
there
is
a
damage
claim.
Keep
the
carton
and
packing
material
even
if
no
shipping
damage
occurs.
Having
the
original!
carton
available
makes
packing
the
unit
much
easier
should
it
ever
be
necessary
to
store
it
or
return
it
to
the
factory
for
service.
NOVE
Fill
out the enclosed
registration
card
and
return
it
to
the
factory
immediately
to
insure
registra-
tion and validation of the warranty.
The
W--4
Wattmeter
should
be
installed
between
the
output
of
the
transmitter
(or
amplifier)
and
the
antenna.
Ordinary
PL—259
coax
connectors
will
couple
correctly
with
the
SO
239
recep-
tacles
on
the
sensing
element.
The
sensing
element
is
completely
removable
for
station
convenience.
It
can
be
removed
by
un-
screwing
the
four
machine
screws
on
the
bottom
of
the
cabinet
that
hold
it
in
place.
In
this
manner
the
sensing
clement
can
be
installed
behind
the
operating
table
so
that
bulky
coax
need
not
be
brought
up.
Approximately
3
feet
of
cable
connects
the
sensing
element
to
the
meter
allowing
a
wide
range
of
installa-
tion
positions.

=>) DRAK
ODEDATION
veo
MAb
VSWR MEASUREMENTS. VSWR ineasurements may be made
easily using the nomograph supphed with the W 4 Wattmeter.
The nomograph may be stored conveniently in the gap between
the main chassis and the outer case of the Wattmeter.
POWER MEASUREMENTS. In order to make full use of the
W—4 it should be explained just what is being indicated on the
meter. There are 3 different types of power to be considered;
forward. reflected, and radiated. In the “forward” position, the
W -4 is reading the swm of the radiated and reflected power,
while in the “reverse” position, it is reading reflected power.
This would stand to reason if you would imagine a “bundle” of
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some of it will be reflected back, thus going in the ‘reverse’
direction. Radiated power can thus be found by subtracting the
“reverse”? power reading from the “forward” power reading.

<> Pe
MAINTENANCE
SERVICE.
The
W—4
was
designed
to
keep
maintenance
to
a
minimum.
Since
the
W—4
is
basically
a
passive
device
and
does
not
use
any
tubes,
it
should
provide
ycars
of
service
with
proper
care.
If
any
problems
arise
that
cannot
be
solved
easily,
we
sug-
gest
that
you
either
return
your
unit
to
your
dealer,
or
write
directly
to
R.
L.
Drake
Service
Department
describing
your
problem
in
detail.
Include
full
information
concerning
external
connections,
control
settings,
type
of
antenna
used,
etc.
Do
not
return
equipment
to
the
factory
without
proper
authorization.
Address
your
request
for
authorization
to:
R. L. Drake Company
540 Richard Street
Miamisburg,
Ohio
45342
ATTN:
Customer
Service
Department
Telephone;
(Area
Code
513)
866-321]
1
Code-A-Phone
Service
after
1630
Hours
E.S.T.
Telex No. 288-017

Ee<2>) DRAKE
DIODE REPLACEMENT. Should either or both of the 1N295
diode rectifiers malfunction, they should be replaced only with
the same type. Diodes with different characteristics may serious-
ly impair the accuracy of the Wattmeter.
ALIGNMENT PROCEDURE.
NOTE
The internal coupler adjustments were preset at
the factory. Since these controls set the accuracy
and null points their adjustment is quite critical.
No attempt should be made to disturb the set-
tings unless precision laboratory equipment is
available.
The following equipment is necessary for alignment:
a. A 50 Ohm dummy load with an SWR of no more than 1.05:1
at 14 MHz capable of handling 1 kW.
b. An accurate RF voltmeter such as the HP410B or Boonton
SICA.
c. A transmitter with variable output to | kW at 14.00 MHz. All
adjustments are made at 14.00 MHz.
d.
A
short
piece
(3
inches)
of
50
Ohm
coax
such
as
RG/8U
or
double male PLR59 connector,
e. One insulated alignment tool.
Remove the coupler from the Wattmeter and carefully remove
the screws and cover from the coupler exposing the printed
circuit board.

Ee) DRAKE
NULL ADJUSTMENT. With the transmitter and dummy load
connected
to
the
respective
jacks
on
the
coupler.and
Wo
4
range
switch
in
the
200
Watt
REVERSE
position,
apply
200
Watts
minimum
to
the
load.
Hany
reflected
power
is
visible,
using
the
insulated
alignment
tool
inserted
through
the
hole
in
the
side
of
the
coupler.
adjust
the
piston
trimmer
for
minimum
reflected
power. If the load is purely resistive this will be essentially zero.
This
correctly
adjusts
the
50
Ohm
reference
level
and
no
further
adjustment
of
the
piston
trimmer
will
be
required.
FORWARD
POWER
ADJUSTMENT.
Remove
the
power
from
the
load,
switch
the
W
4
range
switch
to
700
Watt.
FORWARD,
With
the
RF
voltmeter
connected
across
the
dummy
load.
apply
power
until
voltage
across
the
loud
is
exactly
70.7
Volts
RMS.
Adjust
the
calibration
pot
connected
to
the
brown
wire
unttl
the
W—4
indicates
exacily
100
Watts.
The 200
Watts
FOR-
WARD
position
of
the
W—4
is
now
calibrated
and
care
should
be
taken
not
to
disturb
its
potentiometer
setting.
Switch
the
W-4
range
switch
to
the
2000
Watts
FORWARD
position,
In-
crease
the
power
unti]
the
voltage
across
the
dummy
loud
is
exactly
224
Volts
RMS.
Adjust
the
calibration
pot
connected
to
the
green
wire
until
the
W—4
indicates
exactly
1000
Watts.
Remove
the
power
from
the
load.
The
2000
Watts
FORWARD
range
is
now
correctly
adjusted
and
care
should
be
taken
not
to
disturb
the
setting.

DRAKE
REVERSE
POWER
ADJUSTMENT.
Reverse
connections
to
the
2
coux
connectors
on
the
coupler,
Remove
power
from
the
loud
and
turn
the
Range
Switch
on
the
W
4
to
200
Watts
REVERSE.
With
the
RF
voltmeter
connected
across
the
dummy
load.
apply
power
until
the
voltage
across
the
load
is
exactly
70.7
Voits
RMS.
Adjust
the
calibration
pot
vonnected
to
the
red
wire
until
the
W-4
indicates
100
Watts.
Turn
the
Range
Switch
on
the
W
4
to
2000
Watts
REVERSE.
Increase
power
until
the
voltage
across
the
loud
is
exactly
224
Volts
RMS.
Ad-
just
the
calibration
pot
connected
to
the
white
wire
until
the
W—4
indicates
1000
Watts.
Remove
power
from
the
coupler,
Replace
the
cover
carefully.

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FORWARD
VSWR.
REFLECTED
1.0
2.0
3.0
:
|
70 3.0
4.0 a
50
6.0
‘3 18 30
30
Lay
straightedge
across
scales
En
20
on
appropriate
forward
and
ies
reflected readings and read
V.S.W.R.
on
center
scale.
70
10
100
S.W.R.
CALCULATOR
R.
L.
DRAKE
MODEL
WA/=@@
WATIMETER