FrSky DHT 8ch DIY Telemetry Compatible Transmitter Module

Review of: FrSky DHT 8ch DIY Telemetry Compatible Transmitter Module

Product: http://www.frsky-rc.com/ShowProducts.asp?id=76


Introduction:

FrSKY ACCST technology is proven, approved by many model associations, tested and reviewed as the leading Chinese 2.4Ghz R/C Technology. If you think DSM2 or FASST is the best, think again! New FrSKY ACCST (Advanced Continuous Channel Shifting Technology) gives you secure radio communicatios in 2.4Ghz band. ACCST 2.4GHz system shifts 80 channels around hundred times per second in the 2.4GHz band. This means that the system is completely resistant to interference in that band.

Features:

• Advanced Continuous Channel Shifting Technology (ACCSTis our advanced tecnology it shifts channel hundred times per second and there is no signal conflicts and interruptions) robust frequency agility.
• Easy to bind and very fast link-up.
• Excellent reboot time.
• True Diversity with two antennas.
• All channels can be programmed with Failsafe, quickly and easily.
• Quick and extremely stable in performance.
• Precise and smooth servo response.
• Extended range (1.5km-2.5km).

This is a module that you can add to any PPM biased radio which is basically any AM or FM transmitter and convert it to 2.4 GHz. This allows you to use inexpensive receivers that are 2.4 GHz and an existing favorite radio that has model memory and has digital trims or convert any inexpensive new AM or FM radio like I did. This module may be purchased in many different places. Mine was ordered from Hobby King.

Specifications Module:

Attachment 54375

• Dimension: 55mm*34mm*8mm (2.17”L x 1.34”W x 0.32”T)
• Operating Voltage Range: 6.0V-13.0V (Lipo compatible)
• Operating Current: 50mA
• Output Power: 60mW
• Resolution: 3072 (>11bit)
• Cost: $22.14

Receiver specifications:
Attachment 54376

• Operating voltage: 4.0~7.2V
• Operating Current: ≤30mA
• Specified Range: ≥500m
• Weight：2.6 g
• Latency: 22ms
• Number of Channels: 4CH
• High-precision：3072 error: ±1
• Easy operation and easy to bind
• ACCST Technology
• Failsafe capable and easily adjustable and configurable
• Dimensions: 34.5x19.5x8mm
• Cost: $13.95

2. Setup

A Futaba 3PM 3-Channel FM/2 S3003 Servos radio was used: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGAG4**&P=7

This radio was selected as for this install since it’s inexpensive, has 10 model memory and all digital trims and other nice features like a count up/down timer. It’s easy to find the PPM line and has plenty of room inside the radio casing, and best of all its reliable and easy to modify.


2.1 Installation process:

1 ) Open the transmitter and remove the board you see on the right in fig. 1 that is attached to all the wires that is linked to the main board. Tap off all the wires at the top of the board which are the White, Orange, Red, Black and White as they are not used.
2 ) The wires the module connect the following manner: Module RED→V+ (VDD on radio Red wire); Module BLACK→GND (G on radio Black wire); YELLOW→PPM (SIG on radio red wire).

Attachment 54379
Fig 1.

3 ) The switch may be installed in the crystal section exposed if you need to use it and is accessible from the outside through the crystal hole where the bind button was located or bind more receivers when needed. See fig. 2. Add the antenna through the existing antenna hole and bolt it down.

Attachment 54378
Fig. 2

4 ) Once the module is installed you can close up the radio and power it on.
5 ) Attach the transmitter antenna to the RF connector. Turn the transmitter power on and check the power indicator LED on the new DHT control panel. It is normally light RED.

2.2 Bind procedure

1）The binding on this system was extremely easy; this radio is already in the PPM mode so just turn the transmitter off.
2）Turn your transmitter on while holding the F/S button on the transmitter module. Release it in a few seconds. The RED LED on the transmitter module will flash, indicating the transmitter is ready to bind to the receiver.
4）Connect the battery to the receiver while holding the F/S button on the receiver. The RED LED on the receiver will flash, indicating the binding process is completed. Turn off both the transmitter and receiver.
5）Turn on the transmitter and re-connect the battery to the receiver. The RED SOLID LED on the receiver will indicate the receiver is receiving commands from the transmitter. The receiver/transmitter binding will not have to be repeated unless one of the two is replaced.
After the above steps are completed, both the transmitter and the receiver are ready to be used.

2.3 Range check

The following steps are to be followed to perform the range check of the model before usage:
Place the model at least 60cm (two feet) above non-metal contaminated ground (e.g. on a wooden bench).

1) Place the antenna of the transmitter in a vertical position.
2) Turn on the transmitter and receiver, press the F/S button of the transmitter for 4 seconds to enter range check mode, the RED LED of the transmitter module will be off, GREEN LED will flash rapidly, the BEEPER will sound. The effective distance will be decreased to 1/30 of full range.
3) Walk away from the model while simultaneously operating the controls on the transmitter, confirming that all controls operate normally to a distance of at least 30 meters (~30 yds).
4) Press the F/S button for 1S-4S to exit range check mode, the RED LED will be back on, indicating normal operation is activated.

2.4 Signal loss indicator and failsafe setting

In some special circumstances, such as strong interference, the signal may be lost. When signal is lost in a short period, the receiver continues to try to search for the transmitter, at the same time it keeps the last command from the transmitter, until a new command is received.

Failsafe is a useful feature in which all controls move to a preset position whenever the control signal is lost for a period of time. FrSky receivers support failsafe function for all channels. Follow the steps below to set failsafe:

1) Bind the receiver first and turn on both transmitter and receiver;
2) Move all controls to that desired as the failsafe position;
3) Press briefly the F/S button of the receiver (less than 1 second), the transmitter module will make a long “beep” (for D8R only) or the GREEN LED of the receiver will flash twice, indicating the failsafe position has been set in the receiver.

To disable the failsafe function, re-bind the receiver.

Other relevant documents can be found on the FrSky web page at these addresses:

1) For V8 series: http://www.frsky-rc.com/download.asp?id=21
2) For Two Way series: http://www.frsky-rc.com/download.asp?id=22


Review:

It was easy to install the module. Took about 10 minutes to remove the FM module the radio came with and de-solder all the wires. No modification was needed to add the antenna line into the Futaba radio which was also nice as I had issues to try to convert an Airtronics MX-3 which I abandoned and sold.

The receivers are fairly small but not as small as the ASSAN but they are more affordable and are easy to bind and immediate at that. Once the receiver was bound, it was easy to set the failsafe. All you have to do is turn on the radio don’t move any controls (must be where you want them set all trimmed out already) and hold the button on the receiver, that’s it! You can also use the module with Lipo batteries which is great also.

Testing: Failsafe works as advertised and range is as far as can see. No lost of control nor any interference.

Conclusion: If you are looking to convert any radio like a stock Aquacraft stock AM radio or any other radio to 2.4 GHz this system is excellent and inexpensive.