Problem with FrSky DHT DIY and D6FR/D8R-II receiver - RC Groups
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Oct 31, 2012, 05:51 PM
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Problem with FrSky DHT DIY and D6FR/D8R-II receiver

I wonder if someone can provide suggestions for Range Check with FrSky D6FR and D8R-II receiver.
I installed a DHT DIY kit to my Turnigy 9X transmitter. The main part of the kit is in the module room on the transmitter.
A Turnigy 12A ESC and a 8g servo were connecting to a D6FR for a range check. They were placed on a wood plate. The D6FR was successfully bind with the DHT a few days before the range check. The servo is connected to channel 1 (Aileron) of the receiver. The transmitter was turned on then the receiver was connected to a battery. The transmitter was changed into range-check mode.I had a friend moving the Aileron stick when I was holding the wood plate and walking away from the transmitter. The servo stopped moving when I was just around 15 to 20 meters (I did it several times) away from the transmitter. I also did the range check with another two D8R-II receivers but got similar result. According to the instruction, the effective distance should be 1/30 of the full range (1.5Km), around 50 meters. The signal was not lost even at 150 meters (that's was the farthest distance that I could be away from the transmitter) in normal mode.
Is it a valid range-check test? If it is, what would be wrong, the Tx or Rx?
Any help is appreciated.
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Nov 01, 2012, 11:18 AM
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I would let alone the receiver without anything conductive "big as my belly" around, and move the radio. You should get at least 30 meters, I would investigate any closer distance.
What are the antennas position during test ? For Tx and Rx too.
If you get the same result with both receivers, the culprit must be at Tx side, and I would suspect the Tx antenna or maybe cable to DHT board. Can you unscrew and check the central pin if not broken of too short ?
Do you have any other spare antennas to replace ?
Nov 01, 2012, 10:43 PM
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I should re-do the range check

The antenna of Tx was almost vierticcally pointing to the sky. Both antennas of Rx were pointing to the Tx. I just recalled they should be 90 degreed to each other and neither should point to Tx.
I also did it inside my house and got better result. But it could because the singals were bouncing from the walls to the Rx.
Double check both Tx and DHT antennas. They looked all right. I will re-do it when it is dry outside.

Nov 07, 2012, 07:59 PM
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Re-tested with two D8R-II and two DF6R

I have re-done the range check with two DF6R and two D8R-II and got good result.
The Rx were placed on a wood plate. The wood plate was on top of a foam box about 1 meter high.
A 8g servo was connecting to channel 1 (Aileron) of the Rx and a 2s, 260mAh battery was connecting to a 12A ESC and then to channel 4 (Throttle) of the Rx.
All Rx were bind to Turniby 9X before hand.
The two antennas of the Rx were pointing to different directions, not to the Tx either.Tx antenna was pointing vertically to the sky. Tx and Rx were power on and Tx was changed to Range Check mode.I hold the Tx moving Aileron stick while walking away from the Rx. Clear strait line between Tx and Rx manitained all the time.
And here is the result.

DF6R : The first quick beep started at around 50m distance. Servo arm was still moving with no sign of stopping.

D8R-II : The first quick beep started at around 30m distance. Servo arm was still mvoing. At 50m, same result, quick beep but servo arm was still moving.

I did not go beyond 50m. If the power of Range Check is 1/30 of the normal operation, the Rx would still receive singals at 1.5km distance, which is way behyond my current flying range.

Here is what I have learned.
1. Rx antenna should not point to the Tx. Tx antenna should vertically point to the sky.
2. Walk away with Tx, not Rx.
3. Place the Rx about the same height as your Tx.
4. Even the Tx beep quickly, Rx may still receives the signals. Always test with a servo.

I'm happy now.

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