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Removing shield and diode 7E for better reach

  • rbe2012
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21 Oct 2013 06:06 #14822 by rbe2012
Replied by rbe2012 on topic Removing shield and diode 7E for better reach
It depends on the regulations in your country if the output power is limited. Usual limits are 10mW and 100mW - that's the reason why Walkera sells two different models (not for 7e, AFAIK).
Another point is that if you do the diode mod you make changes to the hardware which is checked for getting a FCC and/or CE approvement - this approval will probably be lost (I am not sure if this will be also true for changing the firmware - at least when it enables a higher output power it's quite expectable).

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22 Oct 2013 14:26 - 22 Oct 2013 14:26 #14877 by RandMental
Replied by RandMental on topic Removing shield and diode 7E for better reach

Dante1 wrote: Someone informed that there may be some legal issues with modifying the range of the 7e with this diode mod. Is this true? The fact that it is manufactured with limited range and modified can have some legal consequences? I plan to build a mod and sell them as a complete kit. Can I be faced with legal actions?

Thanks


Any changes you make will invalidate the FCC and CE certifications of the TX if it affects or changes any of the certification test results.

Check the FCC site for examples of the test required to get a TX certified.

At one stage we were required to submit 5 samples to be kept by the certification authority so that can at any time in the future, they can compare the units sold with the one submitted for testing. ("e" Certification in Europe).

Whether you or the end user (or both) is liable for such changes depends on the laws of the country. Normally they first go for the supplier(s), but in many cases if the end user is doing the actual mod he might also be prosecuted.

If you make an adapter module specifically to "upgrade" the devo, you will probably be liable, compared to selling a couple of components that could be used for this or other things - then maybe not. It is all about the intent
Last edit: 22 Oct 2013 14:26 by RandMental.

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22 Oct 2013 15:31 - 22 Oct 2013 15:37 #14881 by SadSack
Replied by SadSack on topic Removing shield and diode 7E for better reach
I think the FCC site has closed down.I was looking at wrong FCC :blush:

I am interest as to what the thing is your thinking of selling ?
Last edit: 22 Oct 2013 15:37 by SadSack.

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28 Oct 2013 12:05 #15073 by s4ntai
Hello. I just done the diode bridge. Removing the sheet is harder that its said.

My question. How do we know if this mod is working or not? Do i need to just fly the bird and see what happen?

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06 Jan 2014 06:10 #18045 by jamiedg
Replied by jamiedg on topic Removing shield and diode 7E for better reach
Hi, just wanted to share my experience of applying the diode mod to my 7e Tx with original firmware.
First thing - this is a very challenging mod, the pictures shown make it look fairly easy but as said the components are very small - take care.
I used a 60w iron to remove the shield & 30w to short the diode.
Before shorting I measured the component resistance of the in-circuit diode and got same 14.8K ohms from both polarities. Was expecting a lower resistance when the "diode" was forward biased, this had me puzzled?
Decided to press on and using tweezers shorted the diode successfully, for me this seemed the safest option.
I measured the 7e current drawn before and after mod and this does show some expected results. Current (after bind bleeps etc.) before mod was 92mA and 152mA after mod, so we are defiantly using more power. I'm still using the original firmware but plan to flash to Deviation soon.
Hope these readings help any others considering the mod.
Thanks to all for this excellent site.

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06 Jan 2014 06:18 #18046 by rbe2012
Replied by rbe2012 on topic Removing shield and diode 7E for better reach

jamiedg wrote: Before shorting I measured the component resistance of the in-circuit diode and got same 14.8K ohms from both polarities. Was expecting a lower resistance when the "diode" was forward biased, this had me puzzled?

You will get the expected results mostly only when the diode is removed or otherwise separated from the rest. If you do this measuring in-place you do not measure the resistance between the pins of the diode but of the pin of the circuit.
In most cases you will get a better result using a multimeter with a diode test circuit. With this you should see a voltage drop of roundabout 0.7V in one direction and completely in the other.

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06 Jan 2014 07:02 #18049 by jamiedg
Replied by jamiedg on topic Removing shield and diode 7E for better reach
Fully understand, main reason for my post was to share my in-circuit results, I expected a difference - but got none. I thought my 7e was maybe a different version or I had the wrong component. But as you say the only way is to remove the component and then measure. My eyes are not that good so no plans to take shield off again.
Thanks and regards.

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06 Jan 2014 07:12 #18050 by robca
For people looking at this thread in the future: do not use a soldering iron to short the diode. The pictures do not convey how small the working space is (even for people with good soldering skills and some SMD experience)

Even with a fine-tipped iron, you risk damaging the module (and the surface tension from the solder can lift the diode off)

The easiest way to perform the mod is to use conductive ink (the one used to repair PCBs) over the diode. A short is a short, no matter how it's done. Given how small the diode is, even using conductive ink is not super-simple, but it's a lot safer than using a soldering iron. Just put a tiny dab of conductive ink over the diode, and you are done

On rcgroups there are enough reports of people ruining the module to warrant warning folks not to use a soldering iron unless you routinely do SMD work

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06 Jan 2014 07:42 #18051 by apiset
It's a good advise to use a conductive ink pen _if_ you already it, but for me I don't and I'd rather try the soldering iron than buying a conductive ink pen at around $20, almost the same price as buying a new 8s upgrade module.

Let's have some fun challenge and excitement doing this! If I toasted the built-in module, then I can always go for 8s upgrade module later, another learning experience!

BTW, I already did the diode mod using the soldering iron successfully despite that last time I use the soldering iron was like 10+ years ago. :)

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28 Jan 2014 21:55 #19346 by jamiedg
Replied by jamiedg on topic Removing shield and diode 7E for better reach
I read that some people wanted to know how to tell if the Tx diode mod was sucessful. One way (if you can) is to measure the Tx current drawn from the battery.
So for others here are my readings (Battery was showing 5.2v);
Tx-mW mA
150 157
100 147
30 128
10 111
3 106
1 103
100uW 102

Interestingly I put the Tx on lowest 100uW and was able to still get Hoten-X bind at 20M away. Only lost lock when i went behind a double brick wall, but increasing to 1mW restored lock from behind the wall, I was surprised how little power you need. Maybe others can confirm if they get similar readings after diode mod.

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29 Jan 2014 04:43 - 29 Jan 2014 04:44 #19359 by VTdev
Thanks for this hardware mod. It was straightforward with conductive ink.

I just want to check -- in testing the current nightly build, there is now a hardware.ini file as well as a tx.ini file and it looks like the line:

;has_pa-cyrf6936 = 1

is now in the hardware.ini.

There is also a comment in the code about not needing to enable pa-cyrf6936, but I assume that applies to the "enable" line, not the above code line.

So proper procedure now I is to uncomment the above line (as before) by removing the semi-colon.

Or is that now no longer necessary?

Thanks.
Last edit: 29 Jan 2014 04:44 by VTdev.

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29 Jan 2014 04:51 #19360 by PhracturedBlue
Replied by PhracturedBlue on topic Removing shield and diode 7E for better reach
Now that I have the hardware.ini, I think I'll just change it to be explicit, and stop guessing what hardware you have.

Today, the code will default to:
all devo except devo7e:
enable-cyrf6936 = B12
has_pa-cyrf6936 = 1

devo7e:
enable-cyrf6936 = B12
has_pa-cyrf6936 = 0

So yes, you should change has_pa-cyrf6936 to '1' if you make the diode mod

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29 Jan 2014 09:59 #19370 by robca

PhracturedBlue wrote: Now that I have the hardware.ini, I think I'll just change it to be explicit, and stop guessing what hardware you have.

Today, the code will default to:
all devo except devo7e:

enable-cyrf6936 = B12
has_pa-cyrf6936 = 1

devo7e:
enable-cyrf6936 = B12
has_pa-cyrf6936 = 0

So yes, you should change has_pa-cyrf6936 to '1' if you make the diode mod


I would like to make a suggestion. Today the Hardware.ini file says:

; there is no need to enable the cyrf6936 module unless
; it is wired to an alternate port. It is Enabled automatically otherwise


When I read it originally, I didn't realize that for a 7e with a diode mode the default would disable it. I mean, it's logical now that I see your reply

I think it should mention that it's enabled automatically but the default is different for 7e and should be enabled for the diode mod

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29 Jan 2014 14:10 #19375 by VTdev
Thanks PB. I've made the changes. Everything is working fine.

I tested @ 10 mW in the house with receiver 30 feet away. I put the TX just behind a standing metal ironing board with the antenna pointed at the model, which should have considerably attenuated the signal. Response was perfect. Receiver is Orange type DSM2.

Previously in testing with the stock 7e and no diode mod and model set at 10 mW the range outdoors was 20 feet at best, with 90 degree antenna orientation. (With the present firmware release normal setting for unmodded 7e should be "150 mW" to get full output, per manual.)

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29 Jan 2014 14:24 #19376 by Mmon77

Previously in testing with the stock 7e and no diode mod and model set at 10 mW the range outdoors was 20 feet at best, with 90 degree antenna orientation


Wow, that's horrible. My unmodded 7e can easily control a small model out to the range where I lose orientation before I lose signal. I'm using DSM2 as well, but a LemonRX. Don't know if that makes a big difference.

At least you'll have good range now :)

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29 Jan 2014 14:46 #19377 by VTdev
No, that isn't horrible -- its the fact that the output was set to "10 mW" for a stock 7e. If it had been set to 150 mW (per the manual for 7e only) it would have produced full stock power -- of about 10 mW.

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29 Jan 2014 14:59 - 29 Jan 2014 15:01 #19381 by VTdev
On a stock 7e using the firmware build I am testing presently, the power settings seem to work but they are relative values, not absolute values. I don't remember if lower values worked that way for the current release as well.

So 150 mW is the maximum setting -- which on a stock 7e Tx is about 10 mW.

I don't know if lower settings are proportional or if they all even work. But 10 mW at least does work and produces a considerably attenuated signal.

If power settings were proportional and all worked on a stock 7e it might be possible to label them as percentages instead of absolute values. And if really lucky, those percentages would work with the other Devo Tx's. But I don't know if that holds true.

In that case a small table in the manual could show the actual power output vs % for the Tx's.
Last edit: 29 Jan 2014 15:01 by VTdev.

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03 Feb 2014 05:50 #19767 by Jman841
Replied by Jman841 on topic Removing shield and diode 7E for better reach
Finally got this working!

a few tips that helped me for some other people who try this in the future:

Some tips for people who choose to do this mod in the future.

First, enable the mod on deviation so you can tell if it worked or not immediately

1. when taking off the RF Shield, use a exacto knife or small knife to slip under the tabs on the RF Shield when you heat it up, it will allow you to separate it fully from the board and much easier than trying to heat both sides quickly and use tweezers.

2. use conductive paint. I got it for 8 dollars at radio shack.

3. Remove the diode carefully! i tapped it extremely quickly and gently with pressure on the diode with a tooth pick until it was enough to move, then used the tooth pick to fling the diode off. if you slip even a mm you are going to hit a different diode and desolder it (this has happened to many people.)

4. place a small bit of conductive ink to bridge the gap.

5. Test it! the easiest way to do this is bind your heli at the lowest power setting. if it doesn't drop signal at over a foot or 2 then it worked.

Another way to test it is to look at the voltage drop on your battery. Put it in the weakest power setting, check your voltage on the front screen, then put it on the highest power setting. if it drops .02 or more volts then it probably worked. if it only drops .01 volt it probably didn't. this is not exact but was repeatable results from before and after i got it to work.

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03 Feb 2014 06:47 #19768 by Jman841
Replied by Jman841 on topic Removing shield and diode 7E for better reach
one question,

When using my Sim heli load, the output on it is PPM, however, the power output is "Default" which is 150 mW. It seems now that after the mod it is draining the battery pretty quick. Is it still transmitting at full power when the output is on PPM? if it is, is there a way to change this so i can transmit at a low power to save the battery when using just for the sim?

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03 Feb 2014 06:52 #19769 by robca

Jman841 wrote: 3. Remove the diode carefully! i tapped it extremely quickly and gently with pressure on the diode with a tooth pick until it was enough to move, then used the tooth pick to fling the diode off. if you slip even a mm you are going to hit a different diode and desolder it (this has happened to many people.)


A bit too late for you :) but might be helpful to others.

Actually there is no need to remove the diode. A short is a short, no matter if there is a diode underneath or not. The best past of the "conductive ink" mod, is that it's very low risk: just paint over the diode, no need to get a soldering iron near any of the components (beyond removing the shield: a solder sucker tool is your friend for that)

And I don't see why anyone would want to do that, but the conductive ink mod can also be reversed by scraping away the paint.

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