Minimum TX Voltage

[CrazyNorman]

Today my helicopter lost signal about one soccer field away from me and went down. Thank goodness fail safe kicked in, killed the engine, approximated a messy autorotation. Broke some linkages, probably bent the feathering shaft, and stripped one servo, but no broken blades or other expensive parts


What's scary is the short distance at which it lost signal. I've never lost signal this close to me before, but I was able to repeat several times after the crash (2.4ghz WK-2801 Pro, the 100mw version) by carrying away and monitoring the heli.

The only thing I can think of that's causing this is that I was lazy and let me TX battery voltage drop to 11.2v when usually I'm paranoid and recharge the battery at around 11.8v. But really, I've flown much further than this before, nice clear weather today, etc, etc. Tomorrow I'm going to charge the battery on the tx and see if I can walk it out the same/double the distance with no issues (as I've flown it that far before), but I'm paranoid the TX is dying or having issues. Any advice?

[kingmeow]

Hmmm...that's odd. I don't own a Walkera radio but all my Futabas have worked down to 10.5V when using Nicads. My 7C uses lipo and I recharge when it reaches 11.1V but only because I don't want to destroy the battery and not because I was worried about signal distance.

I seriously doubt 11.2V caused it. I would look elsewhere but having said that, it should be an easy experiment to do with the aid of a second person.

[Jerry.K]

How many cells does your Tx have in the battery pack and what type of cells are they?

[CrazyNorman]

I'm definitely gonna run some experiments because like you said, easy way to test range vs battery etc.

My TX is running off of a 1000mah 3S LiPo, charges up to 12.6V, I never let it go below 11.1V with load.

[laminarjack]

I'd check to see what the manufacturer says. Most transmitters use a nominal 9.6V battery which shows slightly higher when fully charged. Even dropping down to 9.6 might not be cause for alarm for some, but for others it might be recharge time.

In any event, I doubt it affects range much.

[Hawkerjet]

I run a LIFE 2100mah in my dx7. Full charge is about 10.0v. I recharge when it gets to 9.6v.
Low voltage alarm is around 8.6v.

It's really nice to only have to charge it about once a month.

[ahahn]

Nominal 8 cell nicad pack voltage is 9.6V. My Futaba 7C alarms at 8.5V.

I doubt that 11.2V is a problem.

I'd check your receiver. ~100m may be a bit far for some of the Park Flyer receivers- if that is what you might be flying. Also the heli frames may be blanking the antenna.

[CrazyNorman]

After reading all of these comments I'm pretty convinced TX voltage isn't the issue. I'm using a Walkera 2801-Pro TX, with a 2801-Pro RX. This is not a park-flyer RX, but one of their full range ones.

I have a few suspicions as to what could cause this:

1. Upgraded from Raptor 50 to Frenzy 50. The Frenzy 50 has G10 side-frames (which I don't believe should cause RF interference), but unlike my Raptor it has an aluminum rotorhead and tailbox, which may cause some

2. I put more gadgets than ever before on this heli. The main one is a Futaba GV-1, which is mounted fairly close to my RX. Would this be a likely source of interference? I've also upgraded to an Arizona Fromeco regulator, but I read it was linear and shouldn't be a source of RF.

3. Either RX or TX on it's way out. I have a spare identical RX I can test to see if the current one is faulty. I'll be upset if the radio is on its way though, I've really enjoyed using it.

[w4llet]

I have been using two tx 2801 pro for my helis (including a 600) and several planes in the last two years.

I really don't know the maximum range of this radio is because I only fly as far I can see the model (800m so far).

But I can assure to you 11v is not your problem....

I use regular Nimh lsd AA batteries and when its fully charge it reaches 10.7v only.

When using 2801-pro in foam planes I normally fly at 600m and battery at 9.6v with no problems. Not a single glitch or signal loss in the last two years....

Three things I can suggest to you:

1. If you are using the 2801-pro rx in the model it have dual circuits and antennas. Make sure antennas are in a L shape (90 degrees each other) and the antennas are not touching any carbon, metal parts, or wires.

2. Look for the jst battery plug inside battery case to the TX - Sometimes it moves a little bit when changing batteries and power supply connection starts to malfunction ( tx turn on and off rapidly). Assure that connector is very well attached in to the tx. Happened to me twice on the ground (thanks god) right after changing batteries.

3. Get rid off random id code and set FIXED ID on TX. If signal is lost or tx turn off and on like i said before, it will bind instantly and you have a change to avoid the crash.

Cheerz.

[Ferrett]

Voltage amount is unlikely. I think you need to go to another field, anywhere, really, and range test that TX/RX. Do it in different directions and get a good feel for the failure distance being equal. A soccer field is not very long for a line of sight TX signal..

The crash location may have been a bad spot for TX RF. If you can reproduce the same problem , in another location at the same distance, I would be concerned about safely using that TX RX.