Telex 1505 - Manual (Page 12)

6.5 Microphone Input
A microphone input is available through a jack
on the front panel. It allows connection of a
handset or palm type microphone through a
standard modular phone connection. The
jumper options allow the use of a carbon,
electret, or dynamic element. The microphone
amplifier is adjustable to accommodate the full
range of microphones. It’s routed through a
compression limiter similar to the receiver cir-
cuits. This compressor operates in a linear fash-
ion below 0.776 Vrms input or will have a
limit of 3 dBm increase if that level is ex-
ceeded. This limiter may also be bypassed by a
jumper selection. The output of the microphone
circuits is normally muted and is gated on by
the PTT switched in the handset or micro-
phone. A jumper is available to simultaneously
mute the speaker during the time the PTT is
initiated so that audio feedback is eliminated.
The output of the microphone circuit is bussed
though switches to the transmit line output am-
plifiers and to the speaker amplifier output so
that the user may select which line or the
speaker that the microphone input circuit can
be applied to.
6.6 Sum Audio
The 1505 has a sum audio input circuit and a
sum audio output circuit which allows matrix
operation with several modules. This allows the
expansion of receive input channels or transmit
line channels. For example, using three 1505s,
one receive input channel can be
switch-selected for up to twelve channels out-
put or conversely twelve receive channels may
be mixed into one transmit channel.
6.7 Controls
Each receive input and microphone input can
be muted externally from the rear panel by a
switched low input, this allows remote muting
by an external source of the various inputs. A
PTT unmutes the microphone audio amplifier
by the PTT switch on the handset or the micro-
phone. This PTT is also routed to the rear con-
nector panel and is activated by a switched low
input.
6.8 Indicators
The speaker and each receive input channel can
be muted. The front panel has an indicator to
visibly indicate which channels have been
muted. The front panel also has a PTT LED
which is illuminated when the PTT switch has
been activated on the handset or microphone.
6.9 Power Supply
The 1505 is intended for operation with a 12
Vdc semi-regulated power supply. The onboard
regulator limits the input voltage and regulates
the output voltages to operate the module under
various input voltages. The power supply is
fixed and non-adjustable. The regulator safely
limits the output current through the module.
Reverse input protection is also provided in
case of an inadvertent reverse voltage input.
Warranty (Limited)
All Vega signaling products are guaranteed
against malfunction due to defects in materials
and workmanship for three years, beginning at
the date of original purchase. If such a mal-
function occurs, the product will be repaired or
replaced (at our option) without charge during
the three-year period, if delivered to the Vega
factory. Warranty does not extend to damage
due to improper repairs, finish or appearance
items, or malfunction due to abuse or operation
under other than the specified conditions, nor
does it extend to incidental or consequential
damages. Some states do not allow the exclu-
sion or limitation of incidental or consequential
damages, so the above limitation may not apply
to you. This warranty gives the customer spe-
cific legal rights, and there may be other rights
which vary from state to state.
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