Telex 1505 User Manual

Page 6

4.4 Securing the Connections
After all power and line connections are made,

the wires should be neatly bundled and secured

in place to prevent accidental breakage when in

service. Use one or more of the cable guides

supplied with the card rack, or tie in place with

appropriate wire ties.

4.5 Interface connector Numbering
The Tellabs (or equivalent) card cage interface

connector pins may have a different numbering

scheme than the 1505. Table 4 depicts the card

edge pin numbers as shown in the schematic,

which is also the same as one type of connec-

tor, followed by two alternate numbering

schemes as used on other connectors. Dili-

gently review the actual connections being

used, to Table 4, to ensure proper connections

are made for optimum performance. Record the

external connections made during installation in

the blanks rows in Table 4’s “User Connec-

tion” column (make copies of Table 4 and keep

records for each 1505).

5. Operation

5.1 Description
This 1505 module has up to four, receive bal-

anced 600 Ω line inputs or high impedance un-

balanced inputs, along with a Mic/Handset in-

put, that is user configurable by dip switch set-

ting, to drive from one to four 600 Ω balanced

transmit line outputs, or an 8 Ω remote speaker.

The module is also capable of summing up to

four receive channel inputs and/or a Mic/Hand-

set input, into one or more transmit line outputs

or the speaker output.
A compressor/limiter circuit is available by

jumper selection for each receive circuit, to

limit the input level to a predetermined setting,

which assists in maintaining proper system lev-

els. This module also contains a summed input

circuit, and a summed output circuit, to allow it

to be used in a matrix, i.e. three modules can

be configured to allow a single input to drive

twelve outputs, or conversely twelve inputs can

be summed to one output.
Active switch input circuits allow for muting

individual receive input channels, or the

speaker. A PTT input activates the microphone

circuit.

5.2 Operating Capabilities
The 1505 accepts up to four balanced or unbal-

anced inputs, switch selectable by the user, to

four balanced line driver outputs. These inputs

are also externally mutable by switched low in-

puts at the rear panel connection. In addition,

the module will accept a microphone or hand-

set input through the front panel jack or the

rear panel connector.

The transmit amplifier is a 600-ohm balanced

line output. The module has four balanced line

outputs. Each amplifier output is adjustable

with a range of -15 to 10 dBm.

The module has a speaker amplifier output that

may drive an eight ohm external speaker with

an output level of 1 watt. The level is adjust-

able.

Any line or microphone input may be switched

(through a module dip switch) to any line out-

put or the speaker output. Three 1505s can be

connected so one line input may drive up to

twelve 600-ohm line outputs. Each input is mu-

table and the control is a switched low on the

rear panel connector. A PTT from the micro-

phone or handset will gate on the microphone

amplifier and is also jumper selectable to mute

the speaker to inhibit crosstalk.

5.3 Controls and Indicators
Front panel LEDs light when the corresponding

receive channel or speaker is muted and when

the microphone or handset PTT switch is acti-

vated.