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Hitec RX/TX comms problem

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Old 11-21-2010, 06:49 AM
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PeacefulWarrior
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Default Hitec RX/TX comms problem

Hi there Y'all,

I am very new to the RC world, and see there is plenty of learning ahead for me.

I have a TX / RX problem and was hoping you can assist me in fault finding this error :-)

Some time back I purchased a plane-kit, which was unfinished and had been sitting for several years in a box, so batteries were quite old.

Everything was working fine initially in terms of the RX/TX controlling all the servos.

Prior to my first lesson, I noticed that the TX battery was in bad shape, and was not charging fully, (8.4v) the TX battery alarm was sounding on Radio although still working and controlling to servos.

I purchased new batteries for both TX and RX which I then charged prior to using, unfortunately I mistakedly forgot to unplug and theycharged for over 24hours.

Both RX and TX batteries report being fully charged both with a multimeter as well as the RX LCD display voltage reading.

Now there is NO comms/servo control between RX and TX.
When I powerup the RX first and then the TX theservos 'glitch'(not sure what the correct word is) but they basically'flinch'but there is no control from the RX?For me this means there must be "some comms" between the two?
I know 'now' that this is the wrong sequence to start up, could that be the cause?

Please help :-0
I looked thro quite a few forums and thought it may be due to the batteries, or perhaps the chrystals?

Any thoughts areMOSTwelcome.
RADIO SET: TX is "Hitec Flash 5" and RX is "Hitec Supreme HFD-07RA" running on ch61 - 30 010 Mhz frequency range
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Old 11-21-2010, 08:29 AM
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michael wood
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Default RE: Hitec RX/TX comms problem

transmitter on first then reciver, reciver off then transmitter also check to be sure that you have the battery conector pluged in right in the tramsmitter and reciver
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Old 11-21-2010, 09:55 AM
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Rodney
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Default RE: Hitec RX/TX comms problem

If you were using the wall wart to charge your transmitter and receiver batteries there will be no harm to them if you left them on for 24 to 48 hours. In fact, the first charges should be at least 16 hours at about 0.1C. Now, charge both all night (if using the wall wart) every evening before you go to fly the next day. That will assure that the batteries are fully charged and will not harm them at the low rate the wall warts usually put out. As to your servos glitching when you turn on the receiver before turning on the transmitter, this is normal but not a recommended procedure; as stated above, always turn the transmitter on first on off last at the end of a flight. This will prevent possible harm from the servos exceeding their travel limits.
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Old 11-21-2010, 04:42 PM
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A.T.
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Default RE: Hitec RX/TX comms problem

Hitec Crystal Label & Colour Codes

1. Fully charged battery should report 10.9<11.2 on Flash 5 TX screen, if higher say 15.5v, polarity has been reversed at some time and service is required.
2. Further to "Slipstick's" good advice on crystals: same question other forum.....
Hitec crystal tags have both a two letter and a colour code. These markings usually on the lower end of the tag so you may need to remove the crystal from the receiver/transmitter to see them.
Crystal tag Indicators:
"RF" = Rx dual conversion FM Blue Tip.
"RA" = Rx single conversion AM/FM Green Tip (or colour coded for 27 Mhz frequencies)
"RS" = Rx single conversion FM (ground use receiver only 75 mhz) - Orange tip.
"TF" = Tx FM Black tip
"TA" = Tx AM Black or Blue tip.

Note you are in the UK. Unfortunately some large UK retailers do not like to stock/order all brands of crystals and blatantly advertise that Futaba crystals can be used in Hitec equipment, this is simply not true.
Quote from an earlier post
"Crystals are no longer interchangeable between brands, contrary to popular belief they are totally different in cut, overtone value and a few other specs. e.g. Hitec DC RX crystals on 35.36 & 40MHz have a frequency 10.7MHz ABOVE the nominal frequency whereas Futaba DC RX crystals are 10.7MHz BELOW nominal frequency. Hitec FM TX xtals are cut at half nominal frequency whereas the Futaba FM TX xtals are cut at 1/3 nominal frequency.
With single conversion RX, whilst you may get reasonable results in good conditions with Hitec xtals in Futaba RX, Hitec crystals must be used in Hitec RX for optimum results. Futaba single conversion RX crystals may appear to work but with proven less range and glitching, especially noticeable in damp weather or wet ground. Local radio technician was surprised but ran a number of tests with result he is also now convinced that there is a significant difference in the crystals as has also been confirmed by the local crystal manufacturer who supplies USA military and others requirements.
For further information, refer to Crystal compatibility between brands"
3. Check TX antenna is screwed securely into place (does not need to be overtightened), and if on bench, RX antenna is extened a little away from the RX,batteries & servos. Tx should be held at least 1m from RX as fully charged batteries soon off charger can lead to swamping (jittering servos) if to close.TX On first Off last.

See also sub Sections
"Glitches & Jitter in Receiver, Servo & ESC - causes and cures " and
"Transmitter - FAQ - Additions, Adjustments, Mode Change, Clonepacs & Repairs." under
"Radio Systems, Accessories, Alterations and FAQ." at:
Alan's Hobby, Model & RC FAQ Web Links

Regards
Alan T.
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Old 12-07-2010, 06:30 PM
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Default RE: Hitec RX/TX comms problem

Excellent information: If there is a radio system problem, the best thing to do is send the equipment to Hitec service. My new Laser 6 system was purchased in 2007, and was stored with batteries charge periodically as needed. This year I decided to use it in my F-22 Hanger 9 Raptor model. When testing the flight controls, the throttle would not operate. The servo was tested with a servo driver, and operated normally. Sent the receiver to Hitec for repair, and it was returned without charge having tested ok. Sent the transmitter and receiver to Hitec, and just received them back. The transmitter had a bad gimbal potentiometer which was replace. With this radio well out of warranty, Hitec repaired it for me at no charge including shipping cost for the tested receiver, and both back to me. This is a company that stands behind the product they sell. THANK YOU HITEC.

AERORICH73

Richard Scherer
Scappoose, Oregon
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