WELZ
OPERATING INSTRUCTIONS
MODEL SP-600 SWR & POWER METER
The SP-600 is a passing power meter which is connected be-
tween a transmitter and antenna for measuring directly the
transmitted power, reflected power and the SWR of the an-
tenna system by transmitting a carrier.
The SP-600 has a high sensitivity and high performance power
sensor featuring flat frequency characteristics over a wide
range, and this power sensor, developed by WELZ, permits
accurate measurement of power and SWR with minimum of
measuring error.
The SP-600 is a wide band measuring equipment covering a
range of 1.6 to 500 MHz. This equipment has three built-in
power sensors, and is capable of measuring simultaneously
three transmitting antenna systems.
•
FEATURES
•
These sensors permits big power measurement, 2kW for
HF band, 200W for other frequencies.
•
Meter lighting and LED indicators permit measurement at
dark place (outside DC 12V power supply).
•
Three wide band sensors (directional couplers) having su-
perior frequency characteristics are built in this meter.
These wide band sensors, developed originally by WELZ,
permits simultaneous measurement of three systems of any
band of HF, VHF and UHF bands.
•
The meter permits selection among three ranges of 20W,
200W, and 2,000W.
•
The minimum SWR measuring sensitivity is 1.5W for RS1,
and 1W for RS 2, and 2W for RS 3.
•
The meter body is surrounded by double or triple shielding
case for eliminating error due to diffraction of high fre-
quency waves. This meter is therefore free from measuring
error due to induction which is often encountered in meters
housed in a plastic casing.
111 NAMES Of PARTS Al\ID
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FUNCTIONS
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Fig. 1 Front panel
(1)
Meter
This meter indicates the SWR value, transmitted power, and reflected
power. The lower red scale is for SWR reading, and the upper three
scales for indication of power value. The power scales are provided in
three different ranges of 2kW, 200W, and 20W, which can be selected
by means of the range selector switch. Both the SWR value and power
value can be read directly on the meter scale, and no correction table
nor frequency characteristics correction knob is needed.
(2)
"RANG E"- switch
This switch is used to change the full scale value on the meter for power
indication to 2kW, 200W and 20W.
(3)
"FUNCTION" switch
Set this switch to "FWD" (forward power) position when reading the
transmitted power on the meter, and to "REF" (reflected power) posi-
tion when reading the reflected power. To measure the SWR value,
first set the transceiver in the carrier sending status, and set the switch
to "CAL" position. Then turn the calbration knob, until the needle
comes up to the position of CAL
A,
and change the function switch-to
"SWR" position. The SWR value can then be read directly on the
meter.
(4)
"CAL" knob
This knob is used to set the meter corresponding to the power when
measuring the SWR value. If turned clockwise, the needle will move to
the right; if turned counterclockwise, the needle will move to the left.
Turn the knob until the needle is aligned correctly with CAL
A
position.
(5)
"SENSOR SELECT" switch
This switch is used to select the DC output detected by three sensors
located on the rear side of this meter.
RS1 is for measurement within the range of 1.6 — 60MHz, RS2 for
measurement within 1.8 — 200MHz and RS3 within 130 — 500MHz.
Since the detected output can be switched over among RS1, RS2 and
RS3, three antenna systems can be compared in the simultaneous
transmission state.
(6)
Sensor Select Display LED.
LED, illuminated by an external power source (DC + 10 to 15V), dis-
plays the sensor of the transmission system being measured.
Fig. 2 Rear panel
(1)
Name plate
(2)
Pass seal
(3)
"RS1.TX" connector
An SO-239 connector for connecting input to the sensor"RS1."Con-
nect a transmitter of 1.6 — 60MHz and less than 2kW to this connector.
(4)
"RS1.ANT" connector
An SO-239 type connector for connecting output of the sensor "RS1."
Connect an antenna or dummy load, or other loading device of 1.6 —
60MHz to this connector.
(5)
"RS2.TX" connector
An SO-239 type connector for connecting input to the sensor "RS2."
Connect a transmitter of 1.8 — 200MHz and less than 200W to this
connector.
(6)
"RS2.ANT" connector
An SO-239 type connector for connecting output of the sensor "RS2."
Connect an antenna, dummy load, or other loading device of 1.8 —
200M Hz.
(7)
"RS3.TX" connector
connection with a transmitter rated less than 200W over the range of
130 to 500MHz.
(8)
"RS3.ANT" connector
SO-239 type connector serving as an input of Sensor RS3. Designed for
connection with antenna, dummy load or any other load equipment
rated at less than 200W over the range of 130 to 500MHz.
(9)
External Power Source Connection Terminal.
Designed for meter lighting or to illuminate sensor display LED. Con-
nection should be made with the power source (DC 12V to 15V),
ensuring the proper polarities. When light is turned off or not in use,
be sure to pull the plug from the power source. Note that this power
source has no relation with measurement functions.
•
BEFORE USING
•
Measurement of transceiver power and SWR with this
meter requires a connecting cable. In such measurement,
be sure to use a 50-ohm coaxial cable, with connectors
attached securely to both ends.
•
For accurate measurement of power, prepare a reliable
dummy load having SWR of less than 1.1.
•
This meter has been adjusted completely in the factory
before shipping. Removal of the case, or tampering the
internal components may cause measusrement error, and
must therefore be avoided.
•
The packing materials (and corrugated cardboard box)
used for packing this meter may also be utilized for pro-
tection of the meter when ordering repair or maintenance
service. It is recommended to keep the corrugated card-
board box together with'the instruction book.
■
OPERATION PROCEDURE
•
The SP-600 permits simultaneous connection of three trans-
mitters and 3 antennas. Make suitable connection to RS1,
RS2 or RS3 on the rear panel, corresponding to the fre-
quency and sending power of the transmitter to be meas-
ured.
