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2.4 conversion & unstable voltage indicator

Old 02-20-2013, 06:35 AM
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seagull extra
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Default 2.4 conversion & unstable voltage indicator

I have a JR 10x and an older 347 that I have 2.4 modules for. I have three differant brands of them... Spectrum, Extreme Link, and FrSky and all three modules have the same problem. The voltage indicator on the radio constantly flutters around and it even seems to be affected by the position of the sticks. Has anyone noticed this problem as well ???
Old 02-20-2013, 07:17 AM
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JIMF14D
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Default RE: 2.4 conversion & unstable voltage indicator

The voltage that is fluctuating is the RX voltage? If so and it changes when you move the sticks, your RX batteyr is too small or you have some binding servos.

Have fun,
JIm D.
Old 02-20-2013, 07:23 AM
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BuschBarber
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Default RE: 2.4 conversion & unstable voltage indicator


ORIGINAL: JIMF14D

The voltage that is fluctuating is the RX voltage? If so and it changes when you move the sticks, your RX batteyr is too small or you have some binding servos.

Have fun,
JIm D.
He was speaking about the Tx voltage as read on the Tx. He said nothing about the Rx.
Old 02-20-2013, 07:41 AM
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Default RE: 2.4 conversion & unstable voltage indicator

I had the same problem. The TX pack was bad even though it was only 1 season old. New pack solved the problem.
Old 02-20-2013, 08:25 AM
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Default RE: 2.4 conversion & unstable voltage indicator

It does not seem to be the transmitter pack. If I put the 72mhz module in the radio the voltage indicator reacts normally.
Old 02-20-2013, 08:29 AM
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Default RE: 2.4 conversion & unstable voltage indicator



That's the same symptoms as mine. Seemed fine with the 72mh module.

Here's the whole tale of woe.

http://www.rcuniverse.com/forum/m_76...tm.htm#7796031

Old 02-20-2013, 10:54 AM
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Default RE: 2.4 conversion & unstable voltage indicator

I still do not think it is battery related as both of my radios display the same symtoms and there does not seem to be anything wrong with either battery in the radios. My voltage only fluters a couple of tenths of a volt but the display flickers very rapidly. ie. the number onthe display never stays the same for more than 1/10 of a second. The radio seems to work fine but I just don't like anything at all not to be right when it comes to the radio.
Old 02-20-2013, 11:08 AM
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Default RE: 2.4 conversion & unstable voltage indicator



Yeah, sounds a little different than my situation. Good luck. Hope you solve the problem.

Old 02-20-2013, 11:48 AM
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Aerocal
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Default RE: 2.4 conversion & unstable voltage indicator

This is a noticeable behavior when converting many 72 Txs to 2.4.The 2.4 module uses the power in pulses and not constantly.The circuit that ultimately provides the display was designed to be stable with a constant current draw.A pulsed current draw will cause the display to jump between values.
It is very possible to mitigate this with a retrofit to the circuit but its not something you want to attempt without the technical knowledge to do it correctly.Every hardware configuration is likely different so there is no "one size fits all" solution to the issue that can be done with a soldering iron and a shade tree.
The best solution is to get a radio that was designed as a native 2.4 unit to begin with.
Old 03-19-2013, 10:00 AM
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JeffH
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Default RE: 2.4 conversion & unstable voltage indicator

I had this exact problem with a 10X. I even called Horizon and they said that the 2.4 module was proabably dying. I just didn't quite buy it since a few months earlier it was fine and it sat in the case. The 72 module worked fine, and voltage was steady without any module. I took the battery out of the cassette, wired it to a plug and put it in my old 8103. Same results, 72mhz fine, 2.4, voltage all over. Seems like slam dunk, bad module... especially since the battery pack cycled within 10% of capacity with a C/10 mah discharge. Each cell checked perfect on voltage.
I still had a hunch something was off. I wired up another battery to the 8103, all is well. Wired the same battery to the 10x, no problems at all. I flew with it, no issues. I started checking the cells' resistances. One cell had a super high reading compared to the rest. I surmised that that the one cell was just not passing current to the module and thus the low and fluctuating voltage readings.
Old 03-19-2013, 01:15 PM
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Default RE: 2.4 conversion & unstable voltage indicator

That's a good possibility, Jeff. The reason you saw it was because old FM radios were continuously sending RF out (CW, Continuous Wave) while 2.4gHz sends data in bursts. Those bursts take more power and draw the voltage down a little. A bad cell could make it appear unstable, depending on how the transmitting vs. battery measurements happen time-wise.

Andy

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