Instruction Manual

AC Millivolt Meter
VT-201E

B71-0388-21

■ About a trademark, a registered trademark
A company name and the brand name mentioned in this instruction manual are thetrademark or the registered trademark of each company or group in each country andregion.
■ About this instruction manual
When copying the part or all of contents of this instruction manual, seek the copyrightholder.
In addition, the specifications of the product and the contents of this instruction
manual are subject to change without notice for improvement.
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about the export.

Table of Contents
1 INTRODUCTION .............................................................................. 1
2 Preliminary Notes ........................................................................... 2
2-1 Chassis grounding terminal ....................................................... 2
2-2 Maximum input voltage .............................................................. 2
2-3 Connection leads ....................................................................... 2
2-4 Full scales:................................................................................. 23 FRONT AND REAR PANELS ......................................................... 3
3-1 Front Panel ................................................................................ 33-2 Front Panel ................................................................................ 54 Basic Operation .............................................................................. 64-1 Voltage measurement ............................................................... 64-2 Use of decibel ranges ................................................................ 64-2-1 dB ....................................................................................... 64-2-2 dBm .................................................................................... 75 Specifications ................................................................................. 86 APPENDIX ..................................................................................... 106-1 Fuse Replacement .................................................................. 106-2 External Dimensions Figure .................................................... 12

USING THE PRODUCT SAFELY■ Preface
To use the product safely, read this instruction manual to the end. Before using thisproduct, understand how to correctly use it.
If you read this manual but you do not understand how to use it, please ask us or yourlocal dealer. After you read this manual, save it so that you can read it, anytime as
required.
■ Pictorial indication
This instruction manual and product show the warning and caution items required tosafely use the product. The following pictorial indication and warning characterindication are provided.
<Pictorialindication>
Some part of this product or the instruction manual
may show this pictorial indication. In this case, if theproduct is incorrectly used in that part, a serious
danger may be brought about on the user’s body or theproduct.
To use the part with this pictorial indication, be sure torefer to this instruction manual.

! WARNING! CAUTION

If you use the product, ignoring this indication,
you may get killed or seriously injured. Thisindication shows that the warning item to avoid
the danger is provided.
If you incorrectly use the product, ignoring thisindication, you may get slightly injured or the productmay be damaged. This indication shows that thecaution item to avoid the danger is provided.

Please be informed that we are not responsible for any damages to the user or to thethird person, arising from malfunctions or other failures due to wrong use of the productor incorrect operation, except such responsibility for damages as required by law.
IUSING THE PRODUCT SAFELY! WARNING! CAUTION■ Do not remove the product’s covers and panels
Never remove the product’s covers and panels for any purpose.
Otherwise, the user’s electric shock or fire may be incurred.
■ Warning on using the productWarning items given below are to avoid danger to user’s body and life and avoid thedamage or deterioration of the product.
Use the product, observing the following warning and caution items.
■ Warning items on power supply● Power supply voltage
There are two kinds of products 'AC100V exclusive use model' and 'Change ofAC115V/AC230V model' depending on the rated voltage. However, if the attached
power cord is specified for a rating of AC125 V, and it is used at a power supply voltage
exceeding AC125 V, it must be changed. If the power cord is not changed to one for
AC250 V specification, an electric shock or fire may be incurred.
● Power cord
(Important） The attached power cord set can be used for this device only.
If the attached power cord is damaged, stop using it and call the company or each sales
office. If the power cord is used without the damage being removed, an electric shockor fire may be caused.
● Protection fuse
If an input protection fuse is blown, the product does not operate. When the fuse isblown, the user cannot replace it. It is needed to remove the product's covers and rear
panel, for changing a fuse. In such case, keep the case closed and consult us or yourlocal dealer.
● Changing the power supply voltage
When the rated power supply voltage is AC100V exclusive use, the rated power
supply voltage cannot be changed. When the rated power supply voltage is AC115V
or AC230V change, the rated power supply voltage can be changed to AC230V orAC115V. Use the product only at the rated power supply voltage indicated on theproduct. Otherwise, a fire may occur. (Please use the power supply code
corresponding to a set voltage.)IIUSING THE PRODUCT SAFELY■ Warning item on Grounding
If the product has the GND terminal on the front or rear panel surface, be sure toground the product to safely use it.
■ Warnings on Installation environment● Operating temperature and humidity
Use the product within the operating temperature indicated in the “rating”
temperature column. If the product is used with the vents of the product blocked orin high ambient temperatures, a fire may occur.
Use the product within the operating humidity indicated in the “rating” humidity
column. Watch out for condensation by a sharp humidity change such as transfer toa room with a different humidity. Also, do not operate the product with wet hands.
Otherwise, an electric shock or fire may occur.
● Use in gas
Use in and around a place where an inflammable or explosive gas or steam isgenerated or stored may result in an explosion and fire. Do not operate the productin such an environment.
Also, use in and around a place where a corrosive gas is generated or spreading
causes a serious damage to the product. Do not operate the product in such anenvironment.
● Installation place
Avoid installing the product on inclined places or on places subject to vibration.
Otherwise, the product may slip or fall down to cause damages or injury accidents.
■ Do not let foreign matter in
Do not insert metal and inflammable materials into the product from its vent and spillwater on it. Otherwise, electric shock or fire may occur.
■ Warning item on abnormality while in use
In abnormal situations, such as “smoke”, “fire”, “abnormal smell” or “irregular noise”
occur from the product while in use, stop using the product, turn off the switch, andremove the power cord plug from the outlet. After confirming that no other devices
catch fire, ask us or your local dealer.

IIIUSING THE PRODUCT SAFELY■ Input / Output terminals
Maximum input to terminal is specified to prevent the product from being damaged.
Do not supply input, exceeding the specifications that are indicated in the "Rating"column in the instruction manual of the product.
Also, do not supply power to the output terminals from the outside.
Otherwise, a product failure is caused.
■ Calibration
Although the performance and specifications of the product are checked under strict
quality control during shipment from the factory, they may be deviated more or lessby deterioration of parts due to their aging or others.
It is recommended to periodically calibrate the product so that it is used with its
performance and specifications stable.
For consultation about the product calibration, ask us or your local dealer.
■ Daily Maintenance
When you clean off the dirt of the product covers, panels, and knobs, avoid solvents
such as thinner and benzene. Otherwise, the paint may peel off or resin surface
may be affected.
To wipe off the covers, panels, and knobs, use a soft cloth with neutral detergent in it.
During cleaning, be careful that water, detergent, or other foreign matters do not get
into the product.
If a liquid or metal gets into the product, an electric shock and fire are caused. During
cleaning, remove the power cord plug from the outlet.
Use the product correctly and safely, observing the above warning and caution items.
Because the instruction manual indicates caution items even in individual items,
observe those caution items to correctly use the product.
If you have questions or comments about the instruction manual, ask us or E-Mail us.

IV1 INTRODUCTION
The VT-201E is versatile AC voltmeter which is able to measure AC voltage
from ranges of 10 Hz to 1 MHz with full scale ranges from 300 μV to 100 V. ThedB scale measures 1V as 0dB and ranges from -90 dB to +41 dB. The
600Ω(1mW) dBm scale ranges from -90 dBm to +43 dBm.
The scales on the meter are graduated up to 1.1 (for +1dB) and these extended
scales are especially useful when measuring the characteristics of audio
amplifiers.

1

2 Preliminary Notes
2-1 Chassis grounding terminal
Make sure the chassis ground terminal is connected to the earth.

2-2 Maximum input voltage
The voltmeter may be damaged if any input voltage exceeding the specified
voltage is applied to it. The specified voltage is determined by adding the peakvalue of the input signal and the superimposed DC voltage
300μV ranges: 300 V
3 V to 100 V ranges: 500V

2-3 Connection leads
When the measured signal level is low (i.e. 300μV) or the measured signal
source impedance is high, the input line is susceptible to external noise. To
resist the noise, shielded wires or a coaxial cable should be used depending on
the noise frequency.

2-4 Full scales:
The VT-201E millivoltmeter adopts a special extended scale which has areading range larger than the conventional full scale.

!

Conventional

VT-201E

0 to 1.0

0 to 1.12

0 to 3.1 (3.2)

0 to 3.5-20 to 0 dB

-20 to +1 dB-20 to +2 dBm-20 to +3.2 dBm

CAUTION

The term “full scale” considers ‘1.0’ on the 0 - 1.12
scales as the rated value. The red ▼ mark is setting at‘1.0’ on the outermost scale.

23 FRONT AND REAR PANELS
3-1 Front Panel3

① Meter
Provide easy readings for both voltage and dB scales.

② ZERO adjustment
Mechanical ZERO adjustment for the pointer.

③ Range selector switch
10 dB step attenuator to select a desired voltage range for an easy readout.

④ Input connector
The terminal where the measured signal is applied.

!

CAUTION

The maximum voltage of DC isolation is ±30V (peakvalue)⑤ Output connector
Provide output signals when the meter is used as a preamplifier. When therange selector switch is setting at 100 mV, the output voltage will beapproximately equal to the input voltage. However, when the range selector
switch is setting to the next higher or lower voltage range, the amplification
factor is decreased or increased by 10 dB respectively.

!

CAUTION

The maximum voltage of DC isolation is ±12V (peakvalue)⑥ Power Switch⑦ Power Indicator43-2 Rear Panel⑧⑧ Appliance AC Inlet

54 Basic Operation
4-1 Voltage measurement① Turn off the power.
② Check the ZERO setting of the pointers. If there is offset, you could use ascrewdriver to adjust the zero adjustment screw at the center of the meter
front cover.

③④⑤⑥Plug the AC plug into the AC line.
Set the RANGE to 100 V and turn on the power.
Connect leads to the INPUT terminal and the load is under testing.
Alter the RANGE selector switch until the pointer is at a position which
located at ≧1/3 of the scale, therefore, the reading can be taken easily.

4-2 Use of decibel ranges
There are two dB scales provided on the dial which have been calibrated as
0dB = 1V
0dBm = 0.775V(1 mW into 600Ω)

4-2-1 dB“Bel” is a logarithmic unit which expresses the ratio of two powers. One“decibel” (abbreviated dB) is one-tenth of a Bel. The dB is defined as follows:
dB = 10 log P2 / P1
If the impedance is at the place where P1 and P2 are equal to each other, theratio of power could be expressed as follows:
dB = 20 log E2 / E1 = 20 log I2 / I1
Decibel is originally the ratio of power as explained above. However, thelogarithm of the ratio of other values (ratio of voltage or current) can also beencalled “decibel”.
For example, If the input voltage of an amplifier is 10 mV and its output voltage
is 10 V, the degree of amplification could be 10 V / 10 mV = 1000 times. This is6

also expressed in dB as follows:
Degree of amplification = 20 log 10 V / 10 mV = 60 dB

4-2-2 dBm
“dBm” is the abbreviation of dB (mW). This decibel value expressed the power
ratio with respect to 1 mW. Normally, “dBm” implies the condition where thepower exists in an impedance of 600Ω
Therefore, “0 dBm” can be signified as the following:
0dBm = 1mW or 0.775V or 1.291mA
The power or voltage levels are determined by adding up the scale readings
and the selected RANGE settings.
ScaleRange(+20 dB)

Level(-1 dB)+=+19 dB(+2 dBm)+ (+10 dBm) =+12 dBm

The dB and dBm scales of the indicating meter are as stated the following:
Range setting

dBdBm+40+20 ~ + 41

+20 ~ +43+30+10 ~ +31+10 ~ +33+20

0 ~ +210 ~ +23+10-10 ~ +11-10 ~ +130-20 ~ + 1-20 ~ + 3-10-30 ~ - 9-30 ~ - 7-20-40 ~ -19-40 ~ -17-30-50 ~ -29-50 ~ -27-40-60 ~ -39-60 ~ -37-50-70 ~ -49-70 ~ -47-60-80 ~ -59-80 ~ -57

-70

-90 ~ -69-90 ~ -67

75 Specifications
Channel1Indicating Meter

1-Pointer(Orange)

Scale Values

Vrms value of sinusoidal wave
dB: 0 dB = 1 V
dBm:0 dBm = 1 mW ( 600 Ω)

Voltage Measurement(12 ranges)

Voltage : 300 μV, 1 mV, 3 mV, 10 mV, 30 mV,100 mV, 300 mV, 1V, 3V, 10V, 30V
and 100 V of full scale
dB: -70 dB to +40 dB
dBm: -70 dBm to +40 dBm

Decibel Range-20 to +1 dB ( 0 dB = 1 V ),-20 to +3 dBm (0 dBm = 1 mW [600 Ω])

Voltage Accuracy

Within ±3% of full scale at 1 kHz

Frequency Response(Reference : 1 kHz)

300μV Range:
20 Hz to 200 kHz≦±3%
10 Hz to 500 kHz≦±10%
Other ranges:
20 Hz to 200 kHz≦±3%
10 Hz to 1 MHz≦±10%

Distortion Factor≦2 % of full scale at 1 kHz

Input ImpedanceApproximately 1MΩ

Input Capacitance≦50 pF

Input Maximum
Voltage(DC + AC peak)

300 V ( 300 μV to 1 V ranges)
500 V ( 3 V to 100 V ranges)** DC isolation
Resistance

0.1 Ω or less

AC Output Voltage

0.1 Vrms ±10% for each range of 1 kHz(at full scale without load)

8Stability against Line
Voltage Fluctuation

Indication change with respect to line voltage
fluctuation of ±10% : is within ±0.5% of fullscale.

AC Power
Requirement

AC115V(97V to 132V) , 50/60 Hz
AC230V(195V to 250V), 50/60 Hz

AC Power
Consumption

10VA or 4.0 Watts, Maximum

Fuse

115V：0.2 A, 250V(T type)
230V：0.1 A, 250V(T type)Operation
Environment*** Compatible
Specification
Dimensions
Maximum Dimensions
WeightIndoor use,
Altitude up to 2000M
Installation Category II
Pollution Degree 200Operating Temperature： +0 C ~ +40 C,<80% relative humidity
00Storage Temperature： -10 C ~ +60 C,<70% relative humidity
LVD

EN61010-1:1993+A2:1995

EMC

EN61326-1:1997+A1:1998
131.9 (W) x 196 (H) x 250 (D) mm
131.9 (W) x 212.9 (H) x 291.4 (D) mm
Approximately 2.7kg**: Between the input common and chassis.
***: Applicable only for units with the CE mark on the rear panel.
NOT applicable for modified units.

96 APPENDIX
6-1 Fuse Replacement
Replace the AC source fuse①

Remove the power cord.

②Remove the fuse socket using a flat screwdriver.

③

Replace the fuse in the holder.

10④Ensure the correct line voltage is lined up with the arrow on the fuse holder.
Insert the fuse socket.

116-2 External Dimensions Figure

127F Towa Fudosan Shin Yokohama Bldg., 2-18-13 Shin Yokohama, Kohoku-ku, Yokohama,Kanagawa, 222-0033 Japan
http://www.texio.co.jp