Valcom VMT-1 User Manual

Issue 0
1 947993
Shorting
Jumper
HI Z Out
600-OHM
Input
HI Z Out
SHLD
CT
Shorting
Jumper in
Normal
Position
HI Z Out
600-OHM
Input
HI Z Out
Shield
600-OHM Balanced
Line Input
To Aux. Input
of Amplifier
Phono
Plug
Phono
Plug
OR
N
O
R
M
M
I
C
SHLD CT
VMT-1
INPUT MATCHING TRANSFORMER
CONNECTIONS
The VMT-1 matches 500-600 Ohm lines to either
a high impedance input or output of an amplifier.
It may be used to connect audio page ports of
telephone systems to most 70 Volt amplifiers.
The VMT-1 provides an impedance match
between a 500-600 Ohm balanced line and
auxiliary high impedance input or 25 Volt output
of an amplifier.
Figure 1
Connection to an auxiliary input of an amplifier is
made using a standard phono patch cable or
screw terminals. Connection to a 500-600 Ohm
input is made to screw terminals. A shorting
jumper is available when the unit is used to
connect a high impedance output to the
microphone input of an amplifier.
DIMENSIONS/WEIGHT
• 1.75" H x 3.75" W x 1.25" D
(4.45cm H x 9.53cm W x 3.2cm D)
• 0.5 lbs. (.23 kg)
Figure 2 shows the VMT-1 used to
connect a 600 Ohm balanced line to the auxiliary
input of a commercial 70 Volt amplifier. If the
amplifier uses phone jacks for auxiliary input
connections a patch cable with male phono ends
may be used for the connection. Shielded single
conductor wiring is used when the amplifier is
equipped with screw terminal connections.
Figure 2 Input Matching Ttransformer
To connect a 600 Ohm line to a ¼
microphone input of an amplifier move the
shorting jumper to the lower 2 header pins on the
unit. The connection the amplifier may be made
using a standard patch cable with phono plugs
and a ¼” male/phono jack adapter.

Valcom VMT-1 Specifications

General

Brand	Valcom
Model	VMT-1
Category	Transformer
Language	English

Summary

VMT-1 Input Matching Transformer

General Connections

Matches 500-600 Ohm lines to high impedance inputs/outputs or 70 Volt amplifiers.

Figure 1: Auxiliary Input Connection

Connects to amplifier auxiliary input using phono cable or screw terminals.

Figure 2: 70 Volt Amplifier Connection

Connects 600 Ohm line to 70 Volt amplifier auxiliary input using patch cables.

Dimensions and Weight

Physical dimensions and weight of the VMT-1 transformer unit.

Connection Procedures

Figure 3: Microphone Input Connection

Connects 500/600 Ohm line to a microphone input using specific jumper settings.

Figure 4: 25V Speaker Line to 600/500 Ohm Input

Matches 25V speaker line common to HIZ Shld. and other side to HIZ out terminal.

Technical Assistance and Warranty

Troubleshooting

Verify connections, check volume, contact factory for assistance with VOM and test set.

Service and Repair

Valcom equipment is not field repairable; send units to Roanoke, VA with detailed tag.

Limited Warranty

Warrants products free from defects for one year; details repair, replacement, and exclusions.