TM 11-6625-524-14-4
e r r o r s . H o w e v e r , the probe is still useful for relative readings. Because of its
shunt capacitance and resistance, the effective impedance drops appreciable above
100MHz.
CONTROLS AND INDICATORS
a. F r o n t panel (figure 3-1)
(1) POWER Switch - a two position ON-OFF switch. Connects AC power to the
v o l t m e t e r at the ON position.
(2) RANGE Selector Switch - enables the selection of any one of the eight
(8) RF voltage or dBm measuring ranges.
(3) SET REF Adjust Control - i s used to electrically zero the voltmeter,
u n d e r no input signal conditions, to the meter's SET REF indication.
(4) Meter - RF voltage measurements are read on the top two (2) meter's dial
scales. All measurements should be read between 30% and 100% of full scale as the
specified accuracies will apply only to those readings. The 1 and 2 marks on the
second dial scale refer to 100V and 200V and apply only to the .001V full scale
range. dBm measurements are read on the dBm (1mV, 50 ohm) dial scale.
(5) Meter Mechanical Zero Adjust - provides mechanical zeroing of the meter
p o i n t e r and is performed with the voltmeter de-energized.
(6) RF Input PROBE Connector - a 9 pin Amphenol type which accepts the probe.
(7) AC LINE Pilot Light - i n d i c a t e s AC power is applied to the voltmeter
a n d is operational.
b. R e a r panel (figure 3-2)
(1) POWER Connector - accepts the 3 wire grounded AC line power cord.
Voltage and frequency requirements are marked on the serial/power plate.
(2) FUSE Holder - contains a 0.3 amp " S 1 o - B l o " fuse. Always replace with
the same type and manufacture as factory installed.
(3) LINE VOLTAGE Selector Switch - slide switch for either 115V or 230V AC
line operation and must be set to agree with the line voltaqe to be used.
(4) DC OUTPUT Connector - phone type jack for obtaining a DC voltage which
i s directly proportional to the full scale reading of the meter. DC output 3 circuit
phone plug furnished. Impedance load of 2K (1.98K
to 2.02K
)is required.
( 5 ) Serial/Power Plate.
( 6 ) Calibration Controls Board.
( 7 ) Calibration Adjust Controls - provides individual range linearization
c o r r e c t i o n adjustments.
OPERATING PROCEDURES
Attach the probe to its front panel connector by lining up the key-way of the probe
input connector with the mating key of the probe plug. Push the plug firmly into
t h e connector and secure by rotating (clock-wise) the plug's collar until locked.
S e l e c t the appropriate probe termination. A t t a c h to the probe's threaded end, finger
tight. Use the high impedance tip for direct measurement or use the 50-ohm ter-
mination adapter for measurements in 50-ohm systems.
Insert the 3 wire grounded AC line power cord into its polarized power connector.
A s c e r t a i n that the line voltage selector switch is set to and agrees with the line
voltage source to be used.
P r i o r to energizing the-voltmeter, check and if necessary, adjust the meter's
m e c h a n i c a l zero. To re-adjust, slowly rotate the mechanical zero adjust screw until
(SET REF) indication occurs. The adjustment is properly made only when the pointer
i s traveling in the direction opposite to the turn of the adjust screw.
Select the desired measuring range. If the level of measurement to be taken is un-
k n o w n , turn the range selector switch to the 3V full scale range.
