Flight Manual: Bookmark J-35OE Draken 1.12024-04-04

Communication

FR31 control panel

FR21 control panel

IFF-2720 transponder

J-35OE has two communication radio transceivers for voice and data communication.

FR31

VHF 104.000–161.975 MHz and UHF 223.000–407.950 MHz with FM and AM modulation

Main radio for voice communication, backup radio for data messages.

FR21

VHF 104.000–159.975 MHz with AM modulation

Main radio for data messages, backup radio for voice communication.

In this simulation FR31 corresponds to COM1 and FR21 to COM2. Both radios support all frequencies between 104.000 and 407.975 MHz. AM/FM modulation is not implemented in Prepar3D.

The radios are connected directly to the main electrical bus and have no master switch.

MISSING GRAPHIC: ../graphics/35oe_radiostack.jpg

Fig. 50 - J-35OE radio control panels

FR31 control panel

MISSING GRAPHIC: ../graphics/35oe_fr31.jpg

Fig. 51 - FR31 control panel

The main radio unit FR31 has a numerical keypad for setting the frequency and selecting preset voice/data communication channels. Preset channels are not used in this simulation.

The FM/AM switch has no function in Prepar3D.

Setting the FR31 (COM1) frequency

Use the keypad to enter the desired frequency. The frequency is shown on the LED display.
Press CL to clear, or press MHz to activate the frequency shown on the display.
Press DIM to cycle the intensity level of the LED display.

If you enter a frequency outside of the allowed range, the display will blink and the radio will revert to the default frequency.

Accepting an ATC frequency in Prepar3D will change the current frequency setting. The new frequency will be shown on the display.

FR21 control panel

MISSING GRAPHIC: ../graphics/35oe_fr21.jpg

Fig. 52 - FR21 control panel

This panel is used to select communication radio mode and presets for FR21 (COM2).

The presets are not functional in this version, the manual tuning unit is used for COM2.

Mode	Real J-35OE	Prepar3D
AUS	FR21 OFF	FR21 OFF
EIN HÖRB	FR21 ON + volume control	FR21 ON
DATEN	Data receive mode	No function
BODEN	Ground control com	No function
UNGER/GER	Antenna select (omni/directional)	No function
D\|C	FR21 = Data \| FR31 = Com	Use FR31 (COM1) for ATC
C\|D	FR21 = Com \| FR31 = Data	Use FR21 (COM2) for ATC
— (minus key)	Use manual tuning - presets disabled	Use manual tuning unit (default)

IFF-2720 transponder

MISSING GRAPHIC: ../graphics/35oe_ssr.jpg

Fig. 53 - IFF-2720 transponder

The IFF-2720 transponder operates in military modes 1 and 2 as well as the civilian modes 3/A and 3/B. Mode C (altitude transmit) is also supported.

The identification code can be set separately for the military mode 1 and civilian modes 3/A/B. Mode 2 is a preset and cannot be changed in flight (not implemented here).