User's Manual

M7X and M7R Page 4-21 Installation

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Audio – Narrow-band (B) Connector

An 8-way RJ48 socket marked NB (B) that is used to connect secondary narrow-band audio and

signalling; this could be, for example, connections to extended analogue controllers.

This connector does not have the same level of configuration as the primary narrow-band audio and

signalling connector, NB (A).

NB (B) can be configured to combine Guard signals simultaneously with the main receiver audio and

squelch.

The pin-out is listed in Table 4-8.

The connector has an integral amber indicator that lights when the PTT input is active.

Note:

All line levels for this connector are equivalent to the average speech level regardless of the

waveform selected. The peak to average ratio of speech is taken to be 13 dB, whereas the peak

to average ratio of a sine wave is 3 dB. Therefore, sine wave test tones are expected to be

10 dB higher than line level setting.

An average speech signal applied at the same level as the line in setting (or a sine wave signal applied

at 10 dB above the line in setting) with the ALC off, will result in the transmitter achieving its specified

modulation level. Similarly, receiving a signal at the same modulation level as the transmitter specified

level, with the audio AGC off, will result in an average speech signal being the same level as the line out

setting (or a sine wave signal being 10 dB above the line out setting).

Table 4-8 Narrow-band (B) Audio Connector Pin-Out

Pin Signal Characteristics Input or Output

NB (B) line out -

NB (B) line out +

Balanced 600 ohm, transformer coupled audio output

adjustable between -20 dBm and +10 dBm in 1 dB

steps. The factory default setting is -13 dBm.

Output

3 PTT indication

Grounding, normally open, solid-state relay that

indicates an active PTT. The relay operates between

-60 V and +60 V ac or dc, at a maximum 100 mA.

Output

NB (B) line in +

NB (B) line in -

Balanced 600 ohm, transformer coupled audio input that

is adjustable between -20 dBm and +10 dBm in 1 dB

steps. The factory default setting is -13 dBm.

Input

6 NB (B) squelch

Grounding, normally open, solid-state relay providing a

squelch indication. The relay operates between -60 and

+60 V ac or dc at a maximum current of 100 mA.

Output

7 Ground 0 V. -

8 NB (B) PTT TTL input. An active low keys the transmitter circuit. Input