Chapter 3. OPERATING INSTRUCTIONS

11-6625-524-14-4

CHAPTER 3

OPERATING INSTRUCTIONS

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GENERAL

T h i s chapter should be read carefully before using the voltmeter. It contains infor-

m a t i o n necessary for proper operation of the voltmeter. To achieve valid readings,

p r o p e r switch settings are required. C o n t r o l s , with the function of each, are listed

in paragraph 3-4. The controls are shown in figures 3-1 and 3-2. Operating pro-

cedures are described in paragraph 3-5.

3-2

POWER LINE REQUIREMENTS

The voltmeter can be used on either 115 or 230V AC power line. A line voltage

s e l e c t o r slide switch, located on the serial/power plate, must be set to agree with

the line voltage to be used.

The voltmeter will operate on power line frequencies from 45Hz to 1000Hz. Unless

o t h e r w i s e specified, t h e AC line rejection (input) filter, is adjusted for use on a

60Hz power line frequency. F o r operation on another power line frequency, it is ad-

visable to retune the filter.

3-3

GENERAL PRECAUTIONS FOR RF MEASUREMENTS

NOTE

Maximum Allowable Overload: Damage to the diode cartridge may result should

t h e following input limits be exceeded:

DC: 400V

RF: 15V RMS or 42V P-P

NOTE

T h e manufacturer's warranty does not apply to burned-out diode cartridges.

a. Overload recovery: Should any range be momentarily overloaded, especially

t h e more sensitive ranges, it is advisable to turn the RANGE switch to the 0.03v

full s c a l e p o s i t i o n t o f a c i l i t a t e a f a s t e r o v e r l o a d r e c o v e r y .

b . P o w e r d i s s i p a t i o n r a t i n g : T e r m i n a t i o n adapters are designed for 5 watt dis-

sipation. Do not exceed 5 watt RF.

c. M i s - t e r m i n a t i o n : High frequency signal generators have terminated output

t r a n s m i s s i o n lines. T h e terminating resistance, c o r r e s p o n d i n g to the character-

i s t i c s impedance of the transmission line, i s usually installed between the out-

put terminals at the free end of the transmission line. Some generators may have

t h e transmission line terminated in its characteristic impedance internally at the

o u t p u t connector. In this case, i f the external transmission line is also in 50 ,

serious measuring errors may result. T O avoid this mis-match, the user must check

t h e generator in question to determine if the line is internally terminated. If

s u c h is the case, the resistor should be disconnected, allowing the 50 termination

o f the voltmeter's probe to become the required output matching resistance. If it

i s not desirable to remove the internal termination resistor, an open circuit

adapter should be used.

d. Measurements using the Hi Impedance Tip: Care must be exercised in measuring

l o w signal levels because of possible stray RF pick-up. The lowest level at which

t h e tip is useful will depend upon the strength of the stray RF field. Since the

probe is a very wide-band device (20KHz to 600MHz), any RF signal present within the

probe's response (AM-FM-TV broadcasting. point-to-point communications, etc.) may

be detected. In addition, above 100MHz,- the inductance of the tip and ground lead,

Plus the probe's shunt capacitance, may cause resonances, c r e a t i n g large measuring

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