Microphone Input, Sum Audio, Controls, Indicators

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.