This D4R-II is a full featured mini sized 4 channel receiver by FrSky.

What makes this receiver different the the D4FR? The D4R-II's data port allows you to connect a sensor hub so you can connect GPS, Variometer, temperature, RPM and all of the other great FrSky sensors. It also has 2 full length detachable antennas. All of this is available in a package just a little larger then the D4FR.

Compatible with FrSky two way telemetry modules: DFT, DJT, DHT, DHT-U

Specifications:

Dimension: 40*22.5*6mm
Weight: 5.8g / 5g (naked)
Operating Voltage Range: 3.5V-10.0V
Operating Current: 60mA
Operating Range: Full Range (>1.5km)
Resolution: 3072 (>11bit)

Features:

Firmware upgradeable!
2 full length antennas (replaceable)
One external analog telemetry port and one digital data-stream port (connect to Sensor Hub FSH-01)
RSSI (PWM) and CPPM output - If CH3 and CH4 are connected by a jumper, CH1 will output CPPM for CH1~CH8, and CH2 will output RSSI (PWM)
Lighter weight and physically smaller than D8R-II Plus & D6FR
Alarm warning on low voltage, poor reception, etc.

Downloads

Instruction Manual for D4R-II

Firmware Upgrade Instructions

FrSky D4R-II 4ch 2.4Ghz ACCST Receiver (w/telemetry)