Valcom VMT-1, User Manual

Page: 1 / 3

Issue 0
1 947993
Shorting
Jumper
HI Z Out
600-OHM
Input
HI Z Out
SHLD
CT
S horting
Jum per in
N orm al
P osition
H I Z O ut
600-O H M
Input
H I Z O ut
S hield
600-O H M B alanced
Line Input
T o A ux. Input
of A m plifier
P hono
Plug
P hono
Plug
O R
N
O
R
M
M
I
C
S H L D C T
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.