Yamamoto sound original meter unit
The meter unit of our company has adopted round appearance by 38mm small size. The situation of a its original work maniac's amplifier of operation can be seen by finish with a precision feeling, leaving a somewhat retro atmosphere. The accuracy of meter has realized 2.5% according to a JIS standard. High-definition appearance can be made without attaching, if a subplate is used together when attaching to a chassis, and a screw appearing.

MI-150 150mA ammeter 8,000yen
It is a full-scale 150mA ammeter. Internal composition expresses and carries out 150mA at the time of a 1mA input. Refer to the following figure for directions for use.
Adaptation vacuum tube: 300B, two A3, PX-25, DA30, etc.
The input sensitivity of 1mA/150mA displays,
Internal resistance 1.6k ohms 40(W) x40 (L) x38 (D)
Attachment hole 38mm-dia. screw interval 32mmx4
MI-300 300mA ammeter 8,000yen
It is a full-scale 300mA ammeter. Internal composition expresses and carries out 300mA at the time of a 1mA input. Refer to the following figure for directions for use.
Adaptation vacuum tube: 211, 845, 212, GM70, 813, 6C33C, etc.
The input sensitivity of 1mA/300mA displays,
180 ohms of internal resistance 40(W) x40 (L) x38 (D)
Attachment hole 38mm-dia. screw interval 32mmx4
MI-100 100mA ammeter 8,000yen
It is a full-scale 100mA ammeter. Internal composition expresses and carries out 100mA at the time of a 1mA input. Refer to the following figure for directions for use.
Adaptation vacuum tube: 2A3, 45, PX-4, AD1, VT-25, VT-52, etc.
The input sensitivity of 1mA/100mA displays,
Internal resistance 1.6k ohms 40(W) x40 (L) x38 (D)
Attachment hole 38mm-dia. screw interval 32mmx4
MI-50 50mA ammeter 8,000yen
It is a full-scale 50mA ammeter. Internal composition expresses and carries out 50mA at the time of a 1mA input. Refer to the following figure for directions for use.
Adaptation vacuum tube: WE205D, WE101D, WE104D, 71A, etc.
The input sensitivity of 1mA/50mA displays,
Internal resistance 1.6k ohms 40(W) x40 (L) x38 (D)
Attachment hole 38mm-dia. screw interval 32mmx4
MU-38 VU meter 8,000yen
It is UV meter displayed from -20dB to +3dB. Since it is set as 0dB=1.228V, use it for the output display of a preamplifier or power amplifier.
Input sensitivity 0dB=1.228V,
Internal resistance 26k ohms 40(W) x40 (L) x38 (D)
Attachment hole 38mm-dia. screw interval 32mmx4
MV}300 Center 0 voltmeter 8,000yen
The center of meter is the voltmeter set as 0V. It can be used for the surveillance of output offset of DC amplifier, and the output electric shock style of PP amplifier.
}300mV voltage display,
Internal resistance 6k ohms 40(W) x40 (L) x38 (D)
Attachment hole 38mm-dia. screw interval 32mmx4
F-38 Meter Flange for M series meter \1,800
When attaching meter, it is a flange fixed on a chassis.
The screw of M3 is turned off at the back and it fixes together with meter on both sides of a chassis. It can also be used for decoration of the vacuum tube attachment part of its original work amplifier in addition to the object for meter. It will be O.K. if a 3.5mm hole is made at intervals of 45.2mm. Amplifier becomes a gorgeous impression only now. Outside dimension 50mm-dia.x6(D) mm, inside diameter 35mm, attachment hole 38 mm dia., and M3 tap interval 32mmx4, hole pitch 45.2mm of a diagonal line
The directions for a meter unit
(When using MI-100)
Directions for use put in and use 100 times as much resistance as cathode resistance for series, as shown in a right figure. In this case, the current which flows into meter becomes 1/100 of the current which flows into R1. Since 1mA flows that 100mA flows into R1 into meter, 100mA will be displayed. In the case of MI-150, this resistor is increased 150 times. In the case of MI-50, this resistor is increased 50 times. In the case of MI-300, this resistor is increased 300 times.
By the case where amplifier is fixed bias, when the value of R1 is small, decide the value of series resistance, taking the value of internal resistance into calculation.