# Communications

Radio power is provided by the essential radio bus, radio bus No. 2, or standby power. Except for those radios capable of operating on standby power, control of power to respective radios is through the radio MASTER SWITCH on the left circuit breaker panel.

### AUDIO SELECTOR PANEL

An audio selector panel is installed at each cockpit station. The panels control transmitter and receiver selections and volume.

<figure><img src="/files/opuJpcJfrJyZMcS6BU3C" alt=""><figcaption><p>B727 - Audio Selector Panel</p></figcaption></figure>

**(1) Communications Receive Switches**\
Raise switches to receive desired audio.\
\
\&#xNAN;**(2) Passenger Announcements**\
Connects all selected audio to PA system.\
\
\&#xNAN;**(3) Transmitter Selector**\
Rotate to select desired facility for transmission. Volume can be controlled by rotating the inner knob\
\
\&#xNAN;**(4) NAV-ADF Filter Switch**\
Select both for total reception. Select VOICE or RANGE to filter desired signal.\
\
\&#xNAN;**(5) Navigation Receive Switches**\
Raise switches to receive desired audio.

### FREQUENCY SELECTOR PANEL

The VHF, NAV and ADF frequency selectors are located in the center pedestal panel.

<figure><img src="/files/eYFfT7L5p8V1us4s4GrL" alt="" width="563"><figcaption><p>B727 - Frequency Selector Panel</p></figcaption></figure>

**(1) Frequency Indicator**\
Displays the selected frequency of the corresponding source.\
\
\&#xNAN;**(2) Transfer Switch**\
Selects the active frequency, indicated by a blue illuminated light.\
\
\&#xNAN;**(3) Frequency Selector**\
Outer knob sets tens and ones digits. Inner knob sets tenths and hundreths digits.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.flightsim-studio.com/boeing-727/systems/communications.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.