ImmersionRC | EzUHF JR Module Manual Supplement 1

EzUHF JR Module Manual Supplement

January 2014
ImmersionRC | EzUHF JR Module Manual Supplement 2

Introduction

Congratulations on your purchase of an ImmersionRC EzUHF ‘JR’ module transmitter. 

This manual is a supplement to the general EzUHF Control System, Overview & Operating Instructions

manual, which may be downloaded from the ImmersionRC Website, and gives more general information 

on the EzUHF system.

This module-based transmitter has a similar feature set to the standard 500mW EzUHF Transmitter, but 

with a more convenient form-factor, and much simpler cabling. 

Specifications

 Output Power 500mW (high), 200mW (low)

 DC Power Input 6v – 13v

 Current Consumption 250mA @ 12V in high power mode, 85mA @ 12V in low power

 Head-tracker Power Same as input voltage

 Channel Count Currently 12 Max. (16 planned)

 Antenna Connector Standard-Polarity SMA

 Frequency Range 430MHz -> 440MHz, with a UK (459MHz option)

 Frequency Bands 431-433, 433-435, 435-437, 436-438, 430-430 EH1

 Spread Spectrum FHSS, 20 slots from a possible 40, PRBS sequence

1 EH = Extreme Hopping, more robust operation due to a 20MHz hopping range, instead of 2MHz. 
ImmersionRC | EzUHF JR Module Manual Supplement 3

Compatibility

The EzUHF JR module is ‘plug and play’ compatible with the following radios:

Manufacturer Model/Notes Photo

FrSky Taranis

Turnigy 9xR

The following radios can be made compatible after a simple modification procedure

Turnigy 9X

Plastic part in the 

module bay needs 

removing in order to 

support the EzUHF JR 

module
ImmersionRC | EzUHF JR Module Manual Supplement 4

Connectors & Controls

Details of the Head Tracker connector pin-out may be found in the main EzUHF manual, mentioned 

earlier in this document. 

Bind Button

High/Low 

Power Switch

SMA Antenna 

Connector

Head Tracker 

Input & Goggle 

Power

Aux Input (future 

expansion)

Micro-USB
ImmersionRC | EzUHF JR Module Manual Supplement 5

Firmware Upgrade

As with all EzUHF equipment, it is important that compatible firmware is installed on both the 

transmitter, and the receiver. 

The EzUHF JR module requires, at minimum, firmware version v1.48b. Receivers should be upgraded to 

v1.48, freely downloaded from the ImmersionRC.com website. 

Note: A small batch of transmitter modules shipped with v1.48a, these should be upgraded to v1.48b 

before use.

To upgrade the firmware on the JR module, follow the below procedure: 

1. Install the latest revision of ImmersionRC Tools on your Windows based PC

2. Remove the module from the radio

3. Switch the High/Low Power Switch to LO power mode

4. Hold down the failsafe/bind button, and connect the radio to a PC

5. Select the ‘EzUHF: Tx, 500mW, 2W, JR’ module from the list on the left

6. the ‘Program’ tab, and select ‘Upgrade Firmware’

7. Select the upgrade file ‘EzUHFFirmware_TxJRModule.fw’, and follow the prompts. 

Settings

There are several settings which may be set while the EzUHF JR Transmitter is connected to the PC.

These include: 

Frequency Band

The EzUHF system hops over many frequencies within a pre-set band. Each set of stick positions sent to 

the model are sent on a different frequency, following a pseudo-random sequence. 

The default band is 433-435MHz as the units are shipped. 

It is important that the band matches between the Transmitter and Receiver. 

Band selections available are: 

431-433MHz

433-435MHz

435-437MHz

436-438MHz

430-450MHz Extreme Hopping

The UK version of the firmware doesn’t have the frequency band selection, and will default to the 

hopping range legal within the UK, around 459MHz.
ImmersionRC | EzUHF JR Module Manual Supplement 6

Typically, the band does not need to be changed from its default setting. Examples of when it should be 

changed are:

- When flying with other LRS users, to avoid the frequency band used by them

- When flying in RF-polluted areas, with strong interfering transmitters

Remote Power Switch

The Remote Power Switch allows a channel from the R/C transmitter to be used to change the output 

power level of the EzUHF transmitter. 

Not commonly used, it is best left at its default setting, which uses the power switch on the back of the 

module to change between the two power levels. 

Head Tracking 

There are various settings which define the behavior of the head tracking support. 

These allow mapping of source channels (channels on which the headtracker emits the pan/tilt/roll 

controls), and the destination channels (channels which are sent to the EzUHF Rx). 

A switch also allows the headtracker to be optionally enabled/disabled with the bind button on the 

module. 

The head-tracker port may also be used to power a set of FatShark goggles, eliminating the need for a 

separate battery. 
ImmersionRC | EzUHF JR Module Manual Supplement 7

Note that the FatShark ‘Trinity’ head tracker is highly recommended for use with the EzUHF system. 

This is really a best-in-class headtracker which uses sensors with 9 degrees of freedom, and absolutely 

zero drift.

Binding

Once the firmware revisions of the Tx and Rx have been verified, and upgrades performed, the 

transmitter may be bound to an EzUHF receiver.

To start the binding process, switch the power switch on the EzUHF JR module to Low power, while the 

radio is turned off. 

Hold down the binding button, and turn on the radio. Keep the button held down until the radio starts 

beeping periodically. This indicates that the Tx is in bind mode. 

Power up the receiver, and press the bind button on the receiver. The LED on the receiver will go out 

while binding is in progress, but then, assuming binding is successful, the LED will start ‘breathing’ 

indicating a successful bind. 

A failed binding is indicated by 6 flashes of the LED on the Rx. If this occurs, ensure that the firmware 

versions match between Tx and Rx, and also ensure that the frequency band band matches. 

Once bound successfully, cycle power to both the transmitter, and receiver, and ensure that the LED on 

the Rx is still ‘breathing’.
ImmersionRC | EzUHF JR Module Manual Supplement 8

Tip: We often get asked why the LED ‘breathes’ like this. Basically, an LED which fades on and off by 

varying the duty cycle is a better indicator of reception quality than a simple on/off LED. While range 

testing for example, signal quality can be estimated by looking at ‘stuttering’ in the LED’s fading. 

Error/Beep Codes

When the EzUHF JR module detects a problem, it will beep in a sequence of long, and short beeps, 

which will indicate what is wrong. 

_ .

Transmitter internal error, return for service (Xtal)

_ . .

Transmitter internal error, return for service (TxOvfl)

_ . . . Detected PCM as opposed to PPM, change R/C Tx Mode to PPM

_ . . . .

PPM not detected at power-up (Tx connected to HT input?)

. . .

PPM Timeout, connection problem between R/C Tx and EzUHF

Common problems are _ . . . which indicates that the R/C Tx is in PCM mode, instead of PPM. The 

EzUHF (and all other equivalent systems) require PPM as input, and not PCM. 

Another common problem is _ . . . . which indicates that a PPM signal was not sensed, generally 

indicating that the R/C Tx is not configured to emit PPM to the module bay connector.

This error may also occur if the R/C transmitter is turned on, and stuck at the ‘switch error’ prompt for 

an extended period of time. During this time, the transmitter doesn’t start emitting PPM.