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Old May 30, 2010, 07:33 PM
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Optima 6 input voltage maximum?

Specs say that the voltage requirements are 4.8-7.4v. Anybody running these 2.4g rx's without BEC on a 2S Lipo? Here the voltage output, when fully charged, would be 8.2 or so volts.

KK
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Old May 31, 2010, 12:28 AM
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Originally Posted by kkooch View Post
Specs say that the voltage requirements are 4.8-7.4v. Anybody running these 2.4g rx's without BEC on a 2S Lipo? Here the voltage output, when fully charged, would be 8.2 or so volts.

KK
Reason I'm asking is because I had a plane dive in from around 200'. Complete loss of control. This plane had a glass fuse/carbon boom with modified antenna (maybe that was it- though others have reported good luck with). This antenna was an Emerson coax 1.13mm antenna with 31mm exposed at the end purchased from Digikey. I lost control of the plane seemingly right where the antenna would have been blocked by the carbon boom. The antenna exited down and to the right around 45 degrees. The crash happened when making a left turn up high.

I had range tested and all was aok. Also had fresh batteries that were charged up full. I had also flown this plane at least a doz. times prior to the crash on a hi-start and no problems.

The plane DID go into fail safe mode. But I had too much "down" elevator programmed into. In its 5-6s dive into the ground, it never regained control. When I tested, the Hitec Optima 6 would always rebind instantly once the signal was re-established. Not this time.

So, the only thing left is that I supplied too much voltage (8.0 v) to the rx.

KK
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Old May 31, 2010, 02:16 AM
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Rx may resist, I powered a Hitec Electron 6 by mistake from a 9.6V 8nimh transmitter pack, and no problems.
I would question rather the servos...
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Old May 31, 2010, 04:02 AM
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Optima Transceivers & Minima Receivers - Operating Voltage Limits.

Quote:
Originally Posted by kkooch View Post
Specs say that the voltage requirements are 4.8-7.4v. Anybody running these 2.4g rx's without BEC on a 2S Lipo? Here the voltage output, when fully charged, would be 8.2 or so volts. KK
Maxima 6 & 9 Receiver operating voltage : 4.8v<8.4v (max 2S)
Minima 6L, 6E & 6T Receiver operating Voltage : 4.8 < 8.4v (max 2S)
Optima 6, 7 & 9ch Transceivers operating Voltage: 4.8 < 8.4v (max 2S) from a receiver battery or ESC power (via servo bus)
or 4.8v<35v using the SPC function.

Optima accept 2S but extremely few servos are capable of running on a 2S lipo. "Optima voltage requirements are 4.8-7.4v being the nominal value of a 2S Lipo. A fully charged 2S Lipo being maximum input voltage to the Servo Bus."
Recommend limit servo side to 5.0v/Max 6.0V with switchmode regulator rather than typical BEC or unregulated Ubec, especially for EP models.
Aurora A9 & Optima RX - Battery - 2S Lipo Voltage Capabilities.

Minimum Voltage for Optima Transceivers is 3.5v.

Minimum Voltage for Minima Receivers is 2.6v.

LiFePO (aka A123 & LiFe) - Alert re False Labels & excess voltage
Users of Genuine A123 for RX packs suggest Low Battery Warning of at least 6.0v to allow time for landing
- refer full text of warning re excess voltage of clones (LiFe) which require a regulator.


HYPERION G3 LiFePO4 Batteries for Radio Transmitters and Receivers - Warning
"SERVOS - Many servos on the market, and particularly many of the lower-cost analog types, cannot operate at the voltage supplied by these LiFe Receiver packs. Attempting to use a servo rated for maximum of 6V or less WILL RESULT in reduced servo life, and may lead to in-flight failure. Any such failure is the sole responsibility of the user."
"If you have any concerns about the voltage rating of your servos, you may choose to run a BEC unit, such as the 5V/6V selectable Hyperion SBEC (HP-TICOOL-BEC), in order to regulate voltage down to suit your servos. This offers greater safety compared to BEC units running off the main flight pack because even if your main flight pack is completely depleted in flight the radio and servos will maintain power via the Rx pack."


Optima Transceiver (RX) - SPC - SPC connection (maximum input is 35V) & Lead Detailed plus Optima Current Draw/Amps & Reset voltages.
Optima Transceiver (RX) - Battery set up for Nitro/Gas models #1 caution re NiMH.
Optima Transceiver (RX) - Battery set up for Nitro/Gas models #2 caution re NiMH.
Data Port Cannot Be Used as a battery port
Telemetry - Battery Voltage via SPC and/or HTS-SS Blue for EP Models
==========================================

Digital Servo - Burnout
==========================================

15Jan11 added: Brownout and Voltage Drops

What is a brownout?

This is what occurs if the voltage to the receiver drops below 3.5v. If this happens, control is lost until the voltage comes back above this threshold.

What can cause the voltage to drop to induce a brownout?

In electric models the receiver relies on the BEC (Battery Eliminator Circuit) to supply it power. These are typically rating from 1.5A – 3A @ 5V – 6V but some servos can actually draw more power than they can provide which can cause the voltage to sag below 3.5V causing a brownout. In most cases the BEC’s are overrated!

For Nitro or Gas powered models you would typically use a battery for power with or without this connected to the RX via a regulator. Again, we are relying on the batteries capability to supply the power needed for the servos. If the servos pull more power than the battery, connector, or voltage regulator can handle, the voltage can sag and cause a brownout. This is why it is always important to use batteries that can supply enough power to the servos for your specific application without having the voltage sag. The most common mistake is to buy on capacity alone. A 2000 - 2500mah AA size cell is a perfect example of a battery that works fine in low current draw applications like a transmitter, but can fall flat on its face when asked to power multiple high power digital servos. It’s always best to use at least a 6V (5 cell) pack or greater.

How can I prevent a brownout?

Hitec offers multiple ways that the user can guarantee that they always have sufficient power for the receiver so that they’ll never have to worry about or suffer a dreaded Brownout ever again.

1.) Hitec provides built in battery telemetry in our AFHSS system which allows the user to monitor their voltage input. The battery telemetry not only reads the voltage in real time but it stores the lowest voltage seen plus provides the ability to set a custom low voltage warning to give you any indication of a potential power problem or a low battery. The absolute best way to test if your battery is sufficient for you application is to activate all the control surfaces by quickly wiggling the sticks for a few seconds and then seeing how low the minimum voltage dropped to. If the drop was over one volt then you should probably not use that battery or regulator.

2.) SPC (Supplemental Power Connection.) This is a unique system only offered by Hitec that allows the user to power the receiver separately from the servos with up to 35V so even in the case that the servos pull down the BEC or battery voltage, the Rx still maintains a connection to the transmitter. In most cases this is only used in electric models and not nitro or gas since the user has the ability to choose the proper battery to use and in electric we are at the mercy of the mass produced ESC’s (Electronic Speed Control) BEC which may or may not be sufficient. The way to use this is to tap power of the connector that the battery plugs into (Up to 8S LiPo) and simply plug this connection into the SPC port. A fringe benefit of using the SPC is now the battery telemetry reads the voltage of the main flight battery and when utilizing the low voltage warning, the user can set the warning so that they know when their flight battery is getting low. This is nice because in many cases where you just use a timer, you may not fly as long as you could, or worse have your battery die unexpectedly.

So there you have it… Hitec’s AFHSS system with built in battery telemetry and the SPC port give the user the tools to protect themselves from ever suffering the dreaded brownout ever again!!! - Mike Mayberry"
================================================

more under
Aurora A9, Spectra 2.4 Module & Optima Transceivers - FAQ & Undocumented Features - Mixes, etups, Tips. {Individual Links often updated}

Alan Tong (Hitec NZ)
Alan's Hobby, Model & RC FAQ Web Links
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Old May 31, 2010, 05:23 AM
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Originally Posted by RENATOA View Post
Rx may resist, I powered a Hitec Electron 6 by mistake from a 9.6V 8nimh transmitter pack, and no problems.
I would question rather the servos...
Servos were all Dymond D-47's and I've powered them up thru Berg Rx via 2S lipos in the past with no problems.
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Old May 31, 2010, 05:28 AM
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Indeed, they are rated for 9V !
In this case you must find the Hitec Rx power ratings
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Old May 31, 2010, 04:21 PM
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Man that sucks! I feel your pain!

From the manual for the Optima 6,7,9 receivers,
Operating Voltage:
4.8 - 7.4V From receiver battery power or speed control (ESC) power
4.8 - 35V Using SPC function

I'm not sure what the "fudge" factor is on the servo bus power. I would think that it would take a fully charged 2S lipo pack (since the nominal power of 2S is "7.4V"), but maybe not Personally I would like to see the servo bus power to match the SPC port for operating voltage, and let the end user worry about the servo's operating voltage.

I think I will verify my fail safe settings to make sure that things come down slowly.

Hate to ask this, but what mode were you in, Normal or Scan? I know Scan mode is really slow in reconnecting with a receiver brown out, or antenna shadowing (compared to Normal mode).
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Old May 31, 2010, 04:51 PM
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Hate to ask this, but what mode were you in, Normal or Scan? I know Scan mode is really slow in reconnecting with a receiver brown out, or antenna shadowing (compared to Normal mode).
I was in Normal mode Guz.

Now, I think figured out the problem. Its the custom antenna I made using the coax. I popped the BODA back on and got >150' (stopped walking). The BODA inside a carbon DLG boom only got around 75'.

Now, I popped the custom antenna I made back on, made sure it was secure, let it dangle down from the carbon boom so it was no where near the carbon and bingo, I only got around 60' range. These range checks were all done in the power down mode.

Am curious what kind of range checks you get with your custom coax antenna?
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Old May 31, 2010, 05:53 PM
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I kept walking, and the Tx resumed normal power before it had any issues. Not sure what the distance was, but it was rather far. Farther than I had ever gotten with range testing 72MHz
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Old May 31, 2010, 07:42 PM
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OK, I went out and flew and range tested. You're not gonna like this... but I got over 450 feet range testing with my alternate antenna

I put my DLG on the ground upside down, with the rudder up, and the antenna was basically on top. Put my converted EVO into rudder test mode, then the module in range test mode, and started walking. When I couldn't tell if the rudder was still moving, I called it quits. Paced the distance back to my plane - ~450 feet.

I'll have to wait till there are other people at the field and get assistance finding the limitation of my alternate antenna.
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Old May 31, 2010, 08:43 PM
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When I couldn't tell if the rudder was still moving, I called it quits. Paced the distance back to my plane - ~450 feet.
If in range test mode using the hitec jr module in the EVO, the module will give out a continuous series of fast beeps. And then, when control is lost, a loud continuous tone emits....so no need to be looking to see if the rudder or whatever is not moving, but still an indicator. Are you sure you are in range test mode with the tx module emitting continuous fast beeps?

If so, then maybe the antenna's I made were bad or had bad connections to the rx. But this would be two coax antennas now that I made in a row that were bad. So, for me at least, there's some consistency in that the coax antenna's I'm using are not measuring up.

KK
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Old May 31, 2010, 09:58 PM
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KK,

I did not know that the Tx module will change the audio tone when it gets out of range. But it never changed from the fast beeps for low power mode when I was testing.

Next time I will just start running away from my plane and wait for the audio to change, then pace the distance back to the plane

I noticed that you didn't use the part that I used from Digikey (A36229-ND). I may have just gotten really lucky in picking a compatible miniature coax.

I do have to admit, that it did take me a couple of attempts before I got it stripped properly. The first couple of times, I went to far and cut through the entire wire bundle.
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Old Jun 22, 2010, 10:13 PM
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KK,

I did not know that the Tx module will change the audio tone when it gets out of range. But it never changed from the fast beeps for low power mode when I was testing.

Next time I will just start running away from my plane and wait for the audio to change, then pace the distance back to the plane
Am curious if this happens with the custom antenna you made Guz. Does your TX beep when you loose signal in range test mode? You can test at 450-500' whatever, by covering the TX antenna with your hand. Also, if low battery, the TX will beep with the BODA on the RX. Don't know if this happens with the custom antennas.

KK
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Old Jun 23, 2010, 03:59 AM
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Hitec system does not signal any way out of range, nor at Tx or Rx side, is one of its main weaknesses, imo.
Was advertised in the first leaflets, but removed from product specs after first batch.
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Old Jun 23, 2010, 08:32 AM
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Originally Posted by RENATOA View Post
Hitec system does not signal any way out of range, nor at Tx or Rx side, is one of its main weaknesses, imo.
Was advertised in the first leaflets, but removed from product specs after first batch.
The spectra module in my EVO sounds a continuous tone when range is lost in low power or range mode. Also, I can see on the model that I've lost input control. I've only been able to confirm this happens in range mode though.

KK
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