Removing shield and diode 7E for better reach

PhracturedBlue wrote: well, that is a first
I need to look over the circuitry to figure out your options.

You could always buy an 8S upgrade module (if they still sell them?) That is a reasonably easy install to replace the stock module (but you also need to get an antenna)

I shortened 4 diodes each. It seems to work fine with longer range than normal one.
Even if it works fine, if there are any chances to interrupt the others' flying, I will never use the 7e.
If you can figure it out, please let me know.
For the fail safe, I am going to buy 8S upgrade module so please look below link whether it right product or not.

8S upgrade module
www.rc711.com/shop/walkera-devention-upg...72.html?cPath=167_24

This is the same I used to update from Devo8 to 8S. It should fit your needs.

rbe2012 wrote: This is the same I used to update from Devo8 to 8S. It should fit your needs.

Thank you! I'm gonna buy it!

PhracturedBlue wrote: note that it does require some soldering to fit in the devo7e, but it is quite easy to do. Nothing like the 7e range-extension mod.

There is no chance you will affect flyers by shorting those diodes. What may happen:
1) worst case, you cook the power-amp and it stops working
2) telemetry doesn't work
3) it doesn't work at all (you've already gotten past this one)

So if it seems to be working, I'd go with it at least until you getthe 8s module.
Please remember to reattach the shield before flying.

I really thank you for your kind reply. From now on, I don't use my 7E until the module has changed. I soldered the shield firmly.
There is one thing easier than 7e range mod: adding two switches because I did it!

I think that changing module is quite a challenge for me but I will do it!
I will search for the threads about module replacement.

Just to clarify: please tell me, do I have to modify tx.ini if I'm on stock firmware? Will it work on stock just by removing diode and bridging its place?

BTW: I've bought Walkera MX400S with Devo 7e - what range should I expect for this set before and after diode mod?

Thanks for any help!

FDR wrote: The stock firmware doesn't have a tx.ini you could modify.

The stock 7E RF module's range is about 30-70m, which will increase to quite a few hundreds after the modification, however with the stock firmware you will not be able to lower the power, it will always tranmit on max...

Sounds good to me! And are there any disadvantages of using 100% power at all the time? I don't know, like interferences at close range, battery drain or something?

This is my first model and I'm total newbie. My goal is to make some aerial photography with GoPro HD Hero. I'm flying lonely (no other models in area) in open spaces outside the city. I'm just affraid that one day I will lose my model due to exceed of the safe range.

And one more thing: my quadrocopter came with Walkera camera gimbal (with two servos; not mounted on copter yet, still in box). Is there an option to connect and control it by Devo 7e?

I ran a range check on my Genius FP this weekend. The 7E diode mod has been completed and pointing down the axis of the aerial I got ~20m from both a 7E and an 8S when running Deviation at the lowest power output. So that is basically my _minimum_ range. Anything other than that and I should be able to go further.

I will need to get out to the field to test out the max range and even then... I'm not sure the field will be big enough.

Similar to Spiegel's experience I've managed to remove & lose -- while examining with tweezers -- the component adjacent to the one that is the subject of this mod.

The subject component is still present and I'm planning on relocating it to the position of the one I didn't intend to remove.

To help clarify the component in the green position is still present (though a little worse for wear). The component in the red position has been removed and lost and the component in the orange position is present and unharmed.


I'm trying to source some extra 'diodes' in case things go from bad to worse...

...and with that in mind I've figured out these are '0402' SMDs (they measure .5mm x 1mm)... but beyond that has anyone figured out what they are specifically?

This may sound silly but are they even really diodes? if so what type? I'm new to SMDs but I'm accustomed to seeing markings indicating polarity / direction on components that are polarized (like diodes typically are).

Based on the photo/deatsheet here they look more like varistors.

So I'd like the challenge that these are infact resistors.

Personally, I'm pretty sure, but electronics isn't my field so I want to leave the door open in case I'm mistaken after all.

I think these are resistors for two reasons:

1. I can't find any 0402 resistors that look like these components. In the datasheets, there's always seems to be a marking indicating polarity. In contrast resistors in this size typically never have a marking.


2. When checking for polarity of the remaining components, I measured the same resistance across the component even when reversing the current flow (reversing the test leads). So no current blocking from one direction compared to the other (what diodes are supposed to do).

My Resistance Readings for the circled components:
Blue: 0 ohms (I'm thinking of picking some of these up to complete the mod)
Orange: 17.8kohm (though I may have damaged or partially bridged this one)
Violet: 10.3kohm
Red: Unknown (Missing!) Update: 10.2kohm



So... with that having been said,

Is there someone out there who is in a convenient position to verify my readings?... and perhaps kindly provide their own reading for the component in the red-circled position?

Edit: I found (a little late) one of PB posts regarding this component in the Devo7E Work thread. Now I am conflicted & perplexed. sigh.

PhracturedBlue wrote: I actually checked it and it does appear to be a diode. I can only measure current though it in one direction. It drops about 0.7V when actually running (as measured by my DSO) which is what a diode would do.
That said, the only reason I think it is used to affect gain is:
(a) those words 'Tuning PA Gain' attached as a description to one resistor on a test circuit
(b) the spec for the SWPA says '>= 2.8V' and it is only seeing 2.54V
(c) SPI traces indicate that they do use max power settings on the CYRF chip all the time and it is believed that this is ~10mW

Nothing else in the document indicates you can control gain this way though, so I'm just guessing.

In am also no specialist in electronics, but I have built some circuits in the past, including some with smd/smt. What I have learned:
- components often have no marking at all if they are too small
- diodes and polarized capacitors have usually one end marked
- resistors often have a 3-digit-number
And what I can tell you from my own experience: You can determine the properties of a electronic device only if it is completely (at least all but one soldering point) isolated. If not, you do not measure the component but the resistance (or whatever you measure) between the two soldering points and there could be paths going through other components somewhere on the board.
So my opinion is: you need someone who is willing (and able) to desolder and measure the components in question and tell you what he has seen (I only have Devo8/12 so I can't help you at this point).

Hi Ymboc

RBE is 100% correct, it is almost impossible to make the correct assumptions from any in-circuit component measurements.

You could try looking at a reference design of the T212 and that may give you a hint as to what these components could be. We know from PB's research that the one you had to remove is a diode (I unfortunately did not check when I removed the one on my Devo7e, so I cannot say what type of diode.)

rc.fdr.hu/RDAT212.pdf

rbe2012 wrote: In am also no specialist in electronics, but I have built some circuits in the past, including some with smd/smt. What I have learned:
- components often have no marking at all if they are too small
- diodes and polarized capacitors have usually one end marked
- resistors often have a 3-digit-number

That's roughly my experience as well.

As you alluded to, 0402 sized capacitors and resistors are typically left unmarked.

rbe2012 wrote: And what I can tell you from my own experience: You can determine the properties of a electronic device only if it is completely (at least all but one soldering point) isolated. If not, you do not measure the component but the resistance (or whatever you measure) between the two soldering points and there could be paths going through other components somewhere on the board.

RandMental wrote: RBE is 100% correct, it is almost impossible to make the correct assumptions from any in-circuit component measurements.

I completely agree except there still is some value in these kinds of observations however tainted.

It's also worth pointing out that given the context of PB's post , PB had made his observations in the same (component-in-circuit) condition.

The component in question is still present in my TX. I will have another crack at removing, cleaning it up and inspecting it for the sake of this discussion. I have some additional soldering equipment arriving in the coming weeks that should help make the task more manageable.

Aside, and perhaps more to the point:
An esteemed community member was kind enough to go to the trouble of re-opening his TX & RFshield to measure the resistance (in circuit) of the red-circled component and found it to be 10.2kohm

With that information and flawed-assumptions in hand I should be back up and running within a few weeks.

Question: Why does the diode or resistor even need to be removed? Bridging over it would present a direct short in either direction and the diode should then be irrelevant. Isn't this easier than removing that thing cleanly?

I think the original message got a bit mixed up over time - you don't have to remove the diode - you can if it makes the work easier - but you could just short it out as you suggest.

Is it necessary to do the antenna mod after doing the range mod? Or is the range okay with the stock stub antenna?

Alex

The stock antenna is a proper dipole, so I would not change the antenna unless you want to do >150m plus, and then change it for one you can bend 90degree to the line of sight to your model.