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rd 80000 conversion Help

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Old 12-14-2010, 09:05 PM
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flybyjohn
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Default rd 80000 conversion Help

(This is the third time I am typing this because it keeps getting erased every time I make an error and have to go back and correct it. ) I want to put a diy FRSKY 2.4 module in my RD8000 tx. I have seen a few post that show pictures of the connection points but require the removal of the crystal to stop the 72 mhz transmisson. I have seen the video (link below) that shows someone has placed a switch in and is able to switch back and forth between 72 and 2.4 mhz. This is what I want to do. I have some photos below that show the circuit board and I think that all the RF stuff is on the right side. There are two wires that each cary 9.79v and 9.86 v. Another wire goes to the ant. and a forth red wire has a 0.01 voltage. there are no other connections to or from this section of the board and the board itself does not have any connectiong circuits to it. I have circled this portion of the board in the photo. The photo also shows where the other how-to post shows where the ppm connection is and it is labeled 1.06 v.

I think that one of the 9 volt wires is powering the RF portion and if I can find out which one, I can put a switch in there. Any help would be greatly appreaciated.
Thank you,
John

Link to video that shows a system working like I want mine to. (may have to cut and past.)
http://www.youtube.com/watch?v=wsUzKTImbAE
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Old 12-14-2010, 09:30 PM
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Default RE: rd 80000 conversion Help

I have a correction to the above description. I took one last look under the board and I see where the ppm solder point shown above is jumped with a solid wire to the points shown on the photo shown below with the solid line. The Power is connected via a resister to the rf portion as shown with the eliptcal connection in the photo below. So I wonder if the two wires that I have shown above as 9.79 and 9.86 volts above comming in or going out of this section of the board?
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Old 12-15-2010, 06:24 AM
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ArchNemesis
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Default RE: rd 80000 conversion Help



Please be aware that this will invalidate the FCC certification for that Tx and you will be operating it "illegally". I realize this is a fairly minimal deterant, but just wanted to make you aware.

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Old 12-15-2010, 06:33 AM
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Default RE: rd 80000 conversion Help

flybyjohn

The text in red is by Zor.
I am confused by your postings and I am coming in to try to clarify.

ORIGINAL: flybyjohn

(This is the third time I am typing this because it keeps getting erased every time I make an error and have to go back and correct it. ) I want to put a diy (do it yourself) FRSKY (FRSKY ???) 2.4 module ( 2.4 what ? 2.4 gigahertz RF module?) in my RD8000 tx. I have seen a few post that show pictures of the connection points but require the removal of the crystal to stop the 72 mhz transmisson. I have seen the video (link below) that shows someone has placed a switch in and is able to switch back and forth between 72 and 2.4 mhz. (2.4 mhz __2.4 megahertz ???) __(looking at that video I see that the fellow has a switch that seem to change which of two servos respond to thesame stick motion depending on the switch position. I do not see anything that has to do with switching RF band from 72 Mhz to 2.4 what? 2.4 Ghz ?) This is what I want to do. I have some photos below that show the circuit board and I think that all the RF stuff is on the right side. At this moment I do not see that what you circled and labelled RF board actually is the RF generating board in this transmitterThere are two wires that each cary 9.79v and 9.86 v. Another wire goes to the ant. that is not obvious to me and a forth red wire has a 0.01 voltage. there are no other connections to or from this section of the board and the board itself does not have any connectiong circuits to it. I have circled this portion of the board in the photo. The photo also shows where the other how-to post (how-to post ???) shows where the ppm connection is and it is labeled 1.06 v.
I wonder what you are saying as "the ppm connection".
I think that one of the 9 volt wires is powering the RF portion and if I can find out which one, I can put a switch in there. Any help would be greatly appreaciated.
Thank you,
John

Link to video that shows a system working like I want mine to. (may have to cut and past.)
http://www.youtube.com/watch?v=wsUzKTImbAE
John,

I may be full of &^#*&^ but I would be thrilled to understand what you are talking about.
Ifirst understood that you wish to be able to operate on both the 72 Mhz radio band and the 2.4 which I assume to be the 2.4 gigahertz band.

Your link to a video supposedly showing that another fellow has done that (switching band).
In that video, I see that the same transmitter stick (apparently the rudder stick in mode 2 transmitters) controls a different servo depending on the position of a switch. I do not see any radio band switching out of that video.

I have some suspicion that the wire where you measured 9.86 volts is bringing the voltage to the modulation generating part of the transmitter and the 9.79 volt wire is going out to the RF section to modulate the RF carrier.

You do not have to respond to this posting. I was just curious enough to try to understand what you are doing.

Have a Merry X'mas

Zor


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Old 12-15-2010, 06:53 AM
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Default RE: rd 80000 conversion Help

Zor,

In the video you'll see that the two servos are plugged into 2 different Rx's operation on different bands, 1 on 72mhz, and the other on 2.4Ghz.   It is demonstrating what he wants to accomplish.

John, I really do think you'd save yourself a lot of time and effort, and NOT spend much more money, to simply get one of the new SD6 Transmitters.  All the functionality and more of the RD8000 (save for 2 channels) and it's on 2.4Ghz.  Then you'd have both systems, operation legally on both bands.

My $0.02 worth.

-mark
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Old 12-15-2010, 07:21 AM
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Default RE: rd 80000 conversion Help


ORIGINAL: ArchNemesis

Zor,

In the video you'll see that the two servos are plugged into 2 different Rx's operation on different bands, 1 on 72mhz, and the other on 2.4Ghz. It is demonstrating what he wants to accomplish.

John, I really do think you'd save yourself a lot of time and effort, and NOT spend much more money, to simply get one of the new SD6 Transmitters. All the functionality and more of the RD8000 (save for 2 channels) and it's on 2.4Ghz. Then you'd have both systems, operation legally on both bands.

My $0.02 worth.

-mark
mark,

In the video the servo appearing nearer the bottom is quite obviously plugged into a receiver and we can see the antenna folded.

The other servo (higher up in the video) is plugged into a little box which I did not make out to be a 2.4 Ghz receiver. I do not see any typical 2.4 Ghz antenna here on my monitor. Then there is two wires going out of the picture. What isbeing shown in the back of the transmitter is and was not obvious to me.

If I understand you well, you are simply suggesting hat he leaves his 8000 as is and buy a sepaate 2.4 Ghz transmitter.

i agree that would be the best and easier way to go.
I am trying in my mind to visualize how two separate RF generator are or can be installed in the same case.

I will look at that video again for the 5th or 6th time.

Zor
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Old 12-15-2010, 07:40 AM
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Default RE: rd 80000 conversion Help

Zor, A little clarification. Yes, I did mean gigahertz for the 2.4. Archnemisis explained what I saw in the video well. FRSKY is the brand of the diy (Do it Yourself) 2.4 gigahertz module. The RF portion of the board is circled (not really a circle but a fence)in photo 1 in post 1 that has all the normal components of a normal RF board, it is just connected via the same board to some other electronics in the tx. It is the area on the bottom right side of the photo #2 in post 1. The antanea wire is labeled in Photo #1 , post 1 above. you need to enlarge it to see all the labels. Trust me, it is directly wired to the antanea. The How-To post refers to the part in the paragraph that I mentioned seeing other post showing how to hook up the wires but this way you still have to remove your crystal to disingage the 72 Mhz signal.

ArchNemisis, I have two 2.4gigahertz diy modules and one 500m range 4 channel tx and one long range 8 channel rx on the way for only 73.00 shipped. 4 channel rx's are only 15.00 = 3.00 shipped and the long range 7-8 channel rx's are only 18 to 20 dollars + 3.00 shipped. SD6 txs are 160.00 plus 10.00 shipping plus a whole lot of money for extra rx's from airtronics.

I did read somewhere that the AMA answered some questions about these modules and the answer from AMA was that if the proper instalation is made per instructions, then they are legal to use, however the manufature of said radio being converted does not recomend the installation nor does AMA. If I competed in competitions I would probably have a lot better equipment and not hesitate to go and purchase newer, better equipment, however I am a struggling family man with young kids and I just love to fly and I have to stretch my dollar as far as it will go.
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Old 12-15-2010, 07:52 AM
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Default RE: rd 80000 conversion Help

Zor, in most all transmitters, there is a section in the case that sends 3 wires to the "radio" portion of the transmitter. There is a power wire (+), a signal wire (ppm), and ground (-) that goes to this section. This section, usually on a board, sends out the transmission signal. If the three wire leads are disconnected from the 72Mhz board and are placed through a switch, you can have the signal and power going to one RF Module (72 Mhz) or the other (2.4gigahertz). The computer radio stays on and does not know or care which RF module the power and signal go to, it just sends the signal. The 2.4 gigahertz RF module is only about the size of a electroic speed control (about 45mm x 35mm x 6 mm) so it can fit in any void spaces in the transmitter case. An extra antanea comes with the 2.4 RF module and gets mounted beside the 72 Mhz antanea.
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Old 12-15-2010, 08:45 AM
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Default RE: rd 80000 conversion Help

flybyjohn and participants,

I now have a clear mental picture of what you are doing and how the setup is.

I wish to thank youand the other participants forthe valuable time to explain to me.

Have a Merry X'mas.

Zor
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Old 12-15-2010, 08:48 AM
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Default RE: rd 80000 conversion Help

Hey John, 2 things,

Not to harp on the legal issue as I'm sure we're all aware that the FCC police don't typically hang out at our field, but I can pretty much guarantee that this would NOT be considered legal.  The certification that's done is very specific to each RF board/tx combo that's manufactured.  'Nuff said about that.

I'm curious regarding your last post.  I realize that powering a different RF deck is easy, but where is the data encoding taking place, and for what type of 2.4Ghz Rx's is it set up for?  None of the 2.4 system out there are particularly compatible with one another.  Does this place also make the Rx that this board uses?  Is it true Spread Spectrum, or is it simply shifting a straight signal up to the 2.4ghz wavelength.  If it's the latter...you're going to likely incur range problems, not to mention interference problems as other 2.4ghz systems bounce through your frequency.
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Old 12-15-2010, 09:27 AM
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Default RE: rd 80000 conversion Help

There have been quite a few range tests with these and they seem to be doing quite well. The range tests have tested good at 5 km line of site with no glitching or loss of control. The link below tests this module and he is an electrical engineer. I have seen some poor reviews from him on other chinese goods but he had great things to say about this one. The signal is spread very well with what they call the ACCST technology which stands for Advanced Continuous Channel Shifting Technology which is the same thing as channel shifting. they claim it shifts 80 channels 100 times a second. Most say the bind between rx and tx is almost instant. when tx power is shut off and turned back on fail safe works good and the link back up is very quick. The rx's are made by the same company. I believe the module and reciever do all the work of encoding. The transmitter only gives the module the ppm signal. The long range rxs have dual antanea that acording to the review actually do shift between the two to pick up the best signal.

rcmodelreviews.com/frskyreview.shtml
rcmodelreviews.com/frskyreview2.shtml
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Old 12-15-2010, 09:51 AM
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Default RE: rd 80000 conversion Help

Here is a statement by AMA reguarding the removal of a 2.4 board from a spectrum DX6 tx and transplant into a JR6102 tx. It was posted in rcgroups website. It would seem that the placement of a fcc compliant module intended to be placed into a tx would fall under more acceptable conditions than pulling the guts from one tx and transplanting them into another tx and that is ok with the AMA and fcc rules.

I don't really care one way or the other. I never intend on selling the tx's and in my neck of the woods the most people I will ever be flying with is about 5. I just thought you might be curious where I saw the information.

Below is the statement
EDIT 17 June 2006 - AMA Postion on this:
(revised to include email header and date, etc., per a suggestion from a member)
-
From: Steve Kaluf
To: Larry Hilgert
Sent: Wednesday, April 12, 2006 11:15 AM
Subject: RE: XP6102DX


Larry, here is AMA's official stance regarding this issue.

Recently, there has been a flurry of activity with regard to various modifications of the Spektrum RC radio systems. Some of the modifications involve rather complicated issues and we're working diligently to research them completely to assure compliance with Federal Regulations, safety and standards that are being developed for the usage of the band. AMA is doing our best to balance the interests of all involved.

In particular, the removal of the Spektrum RF section and it's antenna from the DX6 and replacement in the JR6102 has captured the interest of many. After much research with all parties involved, including review of FCC regulations, it has been determined that it is legal to make the modifications under the following conditions by FCC regulations. The complete Spektrum DX6 RF section can be removed along with it's original antenna and placed into the JR 6102. The FCC identification number from the Spektrum DX6 transmitter must be transferred and prominently displayed on the new transmitter as well. Although the AMA and the manufacturer, Spektrum RC, do not recommend, nor encourage this practice, it falls under FCC regulations as acceptable under the preceding conditions.

Anything more than this immediate modification is beyond this scope of this statement and is being dealt with on a case-by-case basis and will be pursued as resources allow.

Regards,

Steve Kaluf
Technical Director
Academy of Model Aeronautics
United States of America
Ph: 765-287-1256 x 230
Fax: 765-286-3303

Below is the author of the rcgroups position.EDIT 17 June 2006 - My position on AMA's postion:
-
In my opinion (make you own determination) one can take this module (the DX6 radio) and connect it to anything you want to provide the power and control signal - it does *NOT* have to be an XP6102. Part 15.23 allows individuals to do so for up to 5 units for personal use, without any type testing or certification required. The DX6 radio, when used with it's supplied coax and antenna, has already been tested and certified. People get confused (including the AMA apparently) that this radio is NOT covered under Part 95 rules, but IS covered under Part 15 rules, which pretty much encourages the use of spread spectrum technology (with tested and certified radio systems) in many different devices.

In fact, many people have done this with other radios, not just JR radios, and they should be fine under Part 15.23 just as long as the original radio board, coax and antenna is used.

Again, this is just my opinion.
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Old 12-15-2010, 12:32 PM
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Default RE: rd 80000 conversion Help

There are will over 100 pages on the Frsky thread on RCG. I did learn that the FRsky DIY module (and I also think the Corona also) does not like the modulation line (PPM) voltage to go as high as most radios use in feeding the 72 mHz RF section because they are directly feeding it into an ASIC without any buffering. The few of radios I have converted I limited this voltage with a single NPN transistor and a regulator. I was also using the transistor to invert the modulation because it was needed in my case but I did regulate the collector voltage. The time I did not do this the module failed ( but not at first). I do not know if not doing this caused the module to fail or if it was faulty but it did get hot (only one data point). If I were to do it again I would look at using a 741 op-amp with negative gain to keep the modulation voltage down.

From with I have been able to pick up the module will not fail instantly when you power it up if the modulation voltage is too high. Eventually the ASIC will over heats on the input and will fail. Now think of this...it works fine on the bench, it works fine in the plane on the ground. But in the middle of a flight it fails.

I would recomend limiting the PPM or modulation line to 5 volts and in the 100 + page thread on RCG I read that some people were limiting it to 3.7 volts because that was the limit in the spec for the ASIC in the module.

One more comment...the FRsky DIY module does have FCC approval. Look at the back side of the instructions. Also it has the Canadian and European approvals. As long as you don't do anything to make any internal changes to this module you will be fully within the limits of the law. The FCC does not care that you are not using the old 72mHz section. It is the RF that gets the approval, not the encoder and the rest of the box we hold in our hands to fly with. That is why the 72 mHz radios with the modules, you could swap them out without breaking the rules. Just changing crystals is another story and not good.

My FRsky conversions have worked great so far and it looks like there are a lot of very happy people using them. If you have the time read the thread on RCG. There are hours of reading there.

Pete
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Old 12-15-2010, 02:29 PM
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Default RE: rd 80000 conversion Help

Thanks modeltronics, I'll start reading.
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