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Old Feb 21, 2015, 05:29 PM
Be safe son - Fly low and slow
Mad_Mike's Avatar
Canada, ON, Lyn
Joined Feb 2015
155 Posts
Question
RFI problem (I think)

Hi guys:

Now that I can keep my plane in the air long enough I think I've discovered an interference issue from the nearby Cell tower that I rely on for telephone - Ironic.

EVERY time I fly between the steel shed and the tower, I lose communication and the plane glides to a crash. Now I'm also randomly losing communication away from the shed so I can't fly in my best field anymore.

Here is the layout of my field, my flying area is outlined in pink near the shed:


Here is the tower:

The distance between the tower and the shed is .7 Miles.

Closeup of the antennas:


My steel roofed shed, the wall is angled pretty much directly at the tower:


My theory is that the reflections off the shed combined with the direct radiation off the tower are overloading the receiver front end. I'd happily try a Futaba or Spektrum receiver but my FlySky/Hobbyking radio won't bind to it according to HobbyKing. I've only been into this a couple of months and don't want to buy an expensive radio just yet.

Radio and receiver:

So what do you guys think I should do?
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Old Feb 21, 2015, 06:35 PM
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vollrathd's Avatar
Joined Jan 2007
881 Posts
lDifferent Frequency

Quote:
Originally Posted by Mad_Mike View Post
Hi guys:

Now that I can keep my plane in the air long enough I think I've discovered an interference issue from the nearby Cell tower that I rely on for telephone - Ironic.

EVERY time I fly between the steel shed and the tower, I lose communication and the plane glides to a crash. Now I'm also randomly losing communication away from the shed so I can't fly in my best field anymore.


Radio and receiver:

So what do you guys think I should do?
Cellphones are generally running 1.9 Ghz or so, so theoretically the cellphone towers should not interfere with 2.4 Ghz. On the other hand, our transmitters are transmitting milliwatts, and who knows what power levels are being used by those towers. That 0.7 miles away would really result in reduced signal strength from the tower though.

We have a microwave tower located around a mile from my home. Never noted any issues while taxing around my driveway. Makes me want to take a model and transmitter, and run a range test right at the tower itself. Project for next week.

That metal shed is probably a pretty good mirror for microwaves.

Out of curiosity, do you have any friends that are flying with Spektrum receivers, or other mfg? A year or three ago, Spektrum did tests where they had 100 2.4 Ghz radios turned on in one area, then moved the pilot and model some distance away. The test involved flying the model directly over those 100 transmitters. Spektrum also has a signal loss monitor for a few $$$$. I've got one, and after a number of flights with zero signal loss, it was pretty much a waste of time. (Turning off the transmitter did verify the signal monitor worked!)

It's been a few years now, but the defunct RCR magazine did a similar test with Spektrum, Futaba and another mfg. Spektrum did OK, Futaba didn't do so well, and the other mfg nearly crashed. Again that was early on with 2.4 Ghz, and a lot of things have changed since then.

Here is a video of what they did with those 100 transmitters: The actual flying tests start at the 3 minute 30 second point in the video.

http://www.horizonhobby.com/content/dsmx-render-dsmx


I've not seen any other mfg's do this sort of test on video. If they have,IMHO, would be good to post it in this thread for the benefit of all of us.
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Old Mar 03, 2015, 03:44 PM
Be safe son - Fly low and slow
Mad_Mike's Avatar
Canada, ON, Lyn
Joined Feb 2015
155 Posts
Thanks for your reply vollrathd:

I watched that demo video and was impressed. 100 radios adds up to 10W of close frequency radiation.

The trouble seems to have gone away.
I got a new receiver and have had no issues with it despite deliberately flying in the "Dead zone" extensively at various altitudes.
Same with the original receiver on retest.

My new theory is that melted snow in the receiver reduced sensitivity and that in conjunction with tower input caused the loss of comms.

I'm more careful keeping snow out of the receivers and much better at 'landing' so the old aerodrome is open once again!
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Old Mar 03, 2015, 04:00 PM
AndyKunz's Avatar
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Joined Sep 2001
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Water in the rx is a bad thing.

Andy
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Old Mar 03, 2015, 04:41 PM
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Wet receiver, yikes!

Quote:
Originally Posted by Mad_Mike View Post
Thanks for your reply vollrathd:

I watched that demo video and was impressed. 100 radios adds up to 10W of close frequency radiation.

The trouble seems to have gone away.
I got a new receiver and have had no issues with it despite deliberately flying in the "Dead zone" extensively at various altitudes.
Same with the original receiver on retest.

My new theory is that melted snow in the receiver reduced sensitivity and that in conjunction with tower input caused the loss of comms.

I'm more careful keeping snow out of the receivers and much better at 'landing' so the old aerodrome is open once again!

Ah ha

The company I worked for for 45 years sold outdoor electronic controls. And, we had moisture problems inside the steel control cabinets that caused control misoperation and/or failure.

It didn't take a lot of moisture. Even worse, with DC circuits present inside this electric stuff, you can have copper foil eaten away by electrolysis over a period of time. I've seen 30/1000 copper foil paths simply eaten and gone.

The Engineering department finally went to circuit board encapsulation with a layer of potting material 3/8 inch thick to resolve the problems. Not feasible with our receivers, but if you're flying in areas where the receiver can get wet, might be a good idea to cover it in a plastic baggie or similar.

It's not just the receiver that can be hit with moisture problems. Last year I burned up an ESC when snow got inside the model, and the ESC. Melted a two inch diameter hole right through the fuse of the foamie model.
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Old Mar 03, 2015, 07:08 PM
Be safe son - Fly low and slow
Mad_Mike's Avatar
Canada, ON, Lyn
Joined Feb 2015
155 Posts
Quote:
Originally Posted by AndyKunz View Post
Water in the rx is a bad thing.

Andy
Yes, agreed.

After I augered it into the ground(likely at full throttle(can't remember)) for the second time I gave up on patching the nose back together and most "landings" after that resulted in snow packed into the ESC ends and receiver servo connector bank.
I just knocked out the snow and didn't give it a second thought; I had lots else to worry about!
The ESC did quit eventually and I had to take it apart and dry it out. I was surprised it worked fine after that.
Now my ESCs are waterproofed and the receivers are mounted securely above the snow line but I don't crash like that anymore as a rule, things have looked up quite a bit.

I'm impressed with the HK radio but I want to upgrade because it won't save models and has no expo, among other things.
I'm liking the DX6i very much at the minute, I've downloaded the user manual for study.
It's between Futaba and Spektrum for me.
I'm trying to hold off for a while so I can make an informed choice.
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Old Mar 03, 2015, 07:14 PM
Be safe son - Fly low and slow
Mad_Mike's Avatar
Canada, ON, Lyn
Joined Feb 2015
155 Posts
Quote:
Originally Posted by vollrathd View Post
It's not just the receiver that can be hit with moisture problems. Last year I burned up an ESC when snow got inside the model, and the ESC. Melted a two inch diameter hole right through the fuse of the foamie model.
I was pretty lucky.
My ESC wouldn't start one time.
The motor shook like a dog crapping razor blades, then stopped.
I slit off the heatshrink and it was wet inside.
Careful drying with IPA and compressed air put it right.

Us Noobs need you guys to take the big hits and let us off sometimes.

Thanks!
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Old Mar 03, 2015, 08:47 PM
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DX6i

Quote:
Originally Posted by Mad_Mike View Post
Yes, agreed.

After I augered it into the ground(likely at full throttle(can't remember)) for the second time I gave up on patching the nose back together and most "landings" after that resulted in snow packed into the ESC ends and receiver servo connector bank.
I just knocked out the snow and didn't give it a second thought; I had lots else to worry about!
The ESC did quit eventually and I had to take it apart and dry it out. I was surprised it worked fine after that.
Now my ESCs are waterproofed and the receivers are mounted securely above the snow line but I don't crash like that anymore as a rule, things have looked up quite a bit.

I'm impressed with the HK radio but I want to upgrade because it won't save models and has no expo, among other things.
I'm liking the DX6i very much at the minute, I've downloaded the user manual for study.
It's between Futaba and Spektrum for me.
I'm trying to hold off for a while so I can make an informed choice.
The DX6i is a very nice "Entry Level" transmitter. About a half dozen of my club members have them.

As far as radio popularity goes, most of them are pretty good. Spektrum has something called "Model Match" that prevents the pilot from taking off with the wrong model setting in the transmitter. Think reversed ailerons. And, if you travel to the larger fun flies, you'll find that a high proportion of radios have Spektrum labels on the transmitters.

FYI, do buy the best transmitter you can afford though. Down the road you'll not regret it.
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Old Mar 04, 2015, 11:46 AM
Hot glue held together by foam
United States, WA, Vancouver
Joined Aug 2010
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Quote:
Originally Posted by Mad_Mike View Post
Yes, agreed.
I'm impressed with the HK radio but I want to upgrade because it won't save models and has no expo, among other things.
I'm liking the DX6i very much at the minute, I've downloaded the user manual for study.
It's between Futaba and Spektrum for me.
I'm trying to hold off for a while so I can make an informed choice.
Mike , if you're considering the DX6i ( older Spektrum technology ) , take look at the DX6 ( newer Spektrum technology ) . I've been using a DX6i for 4 years and it's a great radio , but if it were to crap out on me I'd replace it with a DX6 . The DX6 has many new features that the DX6i doesn't have , including 250 model memory , telemetry capability , and voice alerts . The one thing the DX6 DOESN'T have is the annoying antenna with the 90* joint ( that the DX6i DOES have ) !

250 model memory on the DX6 seems like overkill , but I have more planes/helis/quadcopters than the 10 model memory my DX6i allows , so who knows - you may also eventually have more than 10 planes/helis/quadcopters .

http://www.horizonhobby.com/SPMR6700...iMcaAsum8P8HAQ
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Old Mar 04, 2015, 01:09 PM
Be safe son - Fly low and slow
Mad_Mike's Avatar
Canada, ON, Lyn
Joined Feb 2015
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I thought the DX6i was newer than the DX6 because of the name.
I guess that explains why so many DX6i are available for sale pretty cheap.
Thanks.

I do want more than 10 models but could easily deal with 10 if there was an SD card which there isn't on the DX6i.
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Old Mar 04, 2015, 01:14 PM
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Illinois
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The DX6 is really "DX6 G2."

Andy
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Old Mar 04, 2015, 01:39 PM
Hot glue held together by foam
United States, WA, Vancouver
Joined Aug 2010
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Quote:
Originally Posted by Mad_Mike View Post
I thought the DX6i was newer than the DX6 because of the name.
Thanks.

I do want more than 10 models but could easily deal with 10 if there was an SD card which there isn't on the DX6i.
When Spektrum came out with the new DX6 , they should have named it something NOT so similar to the old DX6i .

If you do get a Spektrum radio ( DSMX/DSM2 protocol ) , there are receivers available that are a LOT less expensive than genuine Spektrum receivers . The online store is Lemon RX ( another poor name choice ! ) . I've been using them for about two years and have never had a problem .

A bundle of 5 parkflyer receivers is $26 plus shipping , which in my case ( Washington State ) was less than $4 - so a total cost of < $30 for 5 receivers .

http://www.lemon-rx.com/shop/index.p...&product_id=93

For a plane that you will be flying farther ( than your average park ) or higher , I recommend getting a receiver with an additional satellite receiver , so you'll have twice the antennae to pick up the TX signal . The satellite RX should be placed away from the primary RX , with the antennae at a 90* angle to the primary RX antennae .

http://www.lemon-rx.com/shop/index.p...product_id=121

Al
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Old Mar 04, 2015, 02:15 PM
Be safe son - Fly low and slow
Mad_Mike's Avatar
Canada, ON, Lyn
Joined Feb 2015
155 Posts
Quote:
Originally Posted by balsa or carbon View Post
When Spektrum came out with the new DX6 , they should have named it something NOT so similar to the old DX6i .

A bundle of 5 parkflyer receivers is $26 plus shipping , which in my case ( Washington State ) was less than $4 - so a total cost of < $30 for 5 receivers .
No kidding! It may be OK for all you guys who have watched the progression of radio names but for me(new to RC) a DX6i is clearly a newer DX6.
And if it's a "DX6 G2" then that needs to be right on the front plate.

HaHa, I already have the Lemon receiver 5 pack bookmarked. I don't think it's Alzheimers, I think you're just helping a lot of people at once.
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