GAI-Tronics 370-301 Dual Channel 600-Ohm to 33-Ohm Converter - Manual (Page 8)

Pub. 42004-431B
370-301 Dual Channel 600 to 30-Ohm Converter Page 8 of 9
f:\standard ioms - current release\42004 instr. manuals\42004-431b.doc
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Level Adjustments
Channel 1 33-Ohm Volume Level - The 33-ohm volume level potentiometer, R11, adjusts the signal
level out to the 33-ohm line.
Channel 1 33-Ohm Balance - The 33-ohm balance potentiometer, R46, adjusts the sidetone present on
the 33-ohm side of the interface.
Channel 1 600-Ohm Volume Level - The 600-ohm volume level potentiometer, R37, adjusts the signal
level out to the 600-ohm line.
Channel 1 600-Ohm Balance - The 600-ohm balance potentiometer, R34, adjusts the sidetone present
on the 600-ohm side of the interface.
Channel 2 33-Ohm Volume Level - The 33-ohm volume level potentiometer, R57, adjusts the signal
level out to the 33-ohm line.
Channel 2 33-Ohm Balance - The 33-ohm balance potentiometer, R79, adjusts the sidetone present on
the 33-ohm side of the interface. It adjusts the amount of audio that is transmitted to the 33-ohm line
from being heard on the 600-ohm line.
Channel 2 600-Ohm Volume Level - The 600-ohm volume level potentiometer, R81, adjusts the signal
level out to the 600-ohm line.
Channel 2 600-Ohm Balance - The 600-ohm balance potentiometer, R74, adjusts the sidetone present
on the 600-ohm side of the interface.
Bi-directional Alignment
The unit is factory aligned for ideal conditions, such as the 33-ohm line terminated at the unit. For areas
where this is not the case, adjustments may be required to improve audio and sidetone levels.
For sidetone adjustments, the unit should be aligned as two one-way systems and then connected as the
two-way system. The following is the procedure to align the sidetone in each direction.
1. Remove the jumper P7 for Channel 1 or P13 for Channel 2 to deactivate the 600-ohm output. This
will set up the unit for a 33-ohm output only.
2. Apply a signal to the 600-ohm input and adjust the 33-ohm volume level potentiometer, R11 for
Channel 1 or R57 for Channel 2, for the desired output level on the 33-ohm side.
3. Monitor the signal level at pin 1 of P7 for Channel 1 or P13 for Channel 2. In the unit it is located at
the top of the header. This is the sidetone signal level. Adjust the 33-ohm balance potentiometer,
R46 for Channel 1 or R79 for Channel 2 for minimal signal level at pin 1.
4. Install the jumper P7 for Channel 1 or P13 for Channel 2 to activate the 600-ohm output and fine
tune the 33-ohm volume level potentiometer, R11 for Channel 1 or R57 for Channel 2, for desired
output level side.
5. Remove the jumper P3 for Channel 1 or P9 for Channel 2 to deactivate the 600-ohm output. This
will set up the unit for a 33-ohm output only.
6. Apply a signal to the 33-ohm input and adjust the 600-ohm volume level potentiometer, R37 for
Channel 1 or R81 for Channel 2, for the desired output level on the 33-ohm side.