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Radio Interference
#31
RotorTim,

Our discussion was about radio interference. I stated that: "I believe it is an ignition/electromagnetic problem. It is visible when a GoPro is mounted to the outside of the fuselage. You can see the picture oscillate with changes in engine RPM and finally stabilizes at operating power."  

I enclosed a link to show you what I was speaking of, nit the blades but the ignition or electromagnetic interference that is causing radio problems also effects the video image. Watch the link from 50 seconds to about 1min. 10 seconds. Pay attention to the body of the craft. You will notice an oscillation of the image at certain RPM. I feel if the image is being distorted by this ignition or electromagnetic interference, the radio transmission/reception is possible suffering from this same interference. I just wanted to make sure we were on the same page.

https://youtu.be/aY53MB7E7EI

Maurizio is you radio transmission/reception good?

Michael 
XE 285  1205 (Myrtle)
Start: 8/1/2013
Finish: 5/24/2014
Arrived home: 10/11/2014

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#32
Michael,

I watched the video and am still of the opinion that is not from the radio or EM interference. I have mounted gopro's to a lot of things from helicopters (and their gun systems) to mono and biplanes to cars and motorcycles. All have had the same effect until some sort of dampening action was taken to mitigate the effect. Also, on a lot of vehicles (air or not), there sometimes is a point where the vibrations even out but then appear later on....there is a sweet spot in there somewhere.

Here is an example of a mount that dampens the effects of rolling shutter. (Not an endorsement for the product)

https://www.youtube.com/watch?v=lxnZThsaVnE

I would love to know what is possibly causing the interference and ways to mitigate it. I live in an area where good comms are essential!

I know a helicycle guy is who is an electrical genius! Maybe he will come on here and add some thoughts.
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#33
OK, after much frustration where I could transmit and receive while at idle rpm but not understand transmissions or have my transmissions understood at operating rpm, I contacted an avionics specialist. We went over diagrams and changed some grounds and shielding. We had some improvement but not enough. He suggested the problem was the lack of a "ground plane". He wanted to change antennas and add a ground plane. I resisted this plan. I mentioned that this antenna was designed to operate as its own ground plane and was used in many Mosquitos. He wanted to know "do they work well"? I could not confirm their operation as responses to my inquires on this forum were sparse. 

A week later we approached a new plan of attack. He stated that most antenna coax is "single" shielded and the new standard is "double" shielded. He also wanted to find all ignition wiring that is close to the antenna and put space between them. After replacing the coax with the double shielded type and installing "stand-offs" between the ignition wiring and antenna I went to check radio settings. I started the heli and did a radio check then took it to 6,000 rpm and at 50 ft. we had clear two-way communication. I pulled into a hover and flew to the west end of our property (about 1,200 ft.) while we talked. I could finally clearly hear transmissions and he could hear and understand my every word. 

I hope the sharing of this information will help some of you with radio issues, but I guess I was the only one having them.
XE 285  1205 (Myrtle)
Start: 8/1/2013
Finish: 5/24/2014
Arrived home: 10/11/2014

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#34
That's great news!  Thanks for sharing.  I wonder if it was the coax or the spacing of the coax from the ignition wires.  Can you estimate the length where you added the separation and approx. space between them now?  (For length, I'm wanting the distance along the cable path where the two were next to each other, in case that was not clear Smile  )

Daryl
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#35
Daryl,

Thes stand-offs are about an inch and the separation is over a distance of about 2' ( the distance everything comes out of the body to the point coax and wiring separate and coax goes into the tailboom.  I also attached a ground wire to the splitter box and ran it to the engine to dissipate and static that may be generated by the tail rotor and shaft. I believe each thing we did helped with the total outcome. The next move is to add shielding to the spark plug wires, it can't hurt and maybe it will help even more!

Michael
XE 285  1205 (Myrtle)
Start: 8/1/2013
Finish: 5/24/2014
Arrived home: 10/11/2014

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#36
thanks Michael!
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#37
Well done Michael. Radio issues have been a long standing issue that we've had several attempts at fixing but it sounds like your's may be the best.
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#38
John,

I knew there have been radio issues but I thought I would get more feedback from other on the forum! In my eyes this forum is for the exchange of information to solve problems and I have tried to do my part. Any issue I encounter I try to make it known to others, I just wish there was more reciprocation.

Michael
XE 285  1205 (Myrtle)
Start: 8/1/2013
Finish: 5/24/2014
Arrived home: 10/11/2014

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#39
I installed the double insulated antenna coax on my 285 and most if not all the radio static is gone. Thanks for the idea! With that said, I still have the problem of the noise from the motor tripping the mic on my MGL radio. Can anyone share their resolution to this issue? What settings in the radio do you use?
Thanks.


Sent from my iPhone using Tapatalk
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#40
(10-22-2017, 01:08 AM)Chamberlain Wrote: I installed the double insulated antenna coax on my 285 and  most if not all the radio static is gone.  Thanks for the idea! With that said, I still have the problem of the noise from the motor tripping the mic on my MGL radio.  Can anyone share their resolution to this issue?  What settings in the radio do you use?
Thanks.


Sent from my iPhone using Tapatalk

Chamberlain,

Glad the double shielded coax helped! I don't know what MGL you are using, I have a MGL V-10. I would think the settings would be similar between the V-10 and V-6. I adjusted my "Mic Level" to 3dB, "Mic Filter" is "ON". As for the "VOX" mine is set at 8. This setting is dependent on "where" you get the most noise although that setting is automatically applied across the Low, Mid, and High range. The "squelch" has to be played with because it will be at one level at idle and another at operating RPM. 

Please let me know if this additional information helps. As you may have read, I am really trying to get forum member to speak up, be more active, and increase the flow of information and support in order to keep all members engaged!

Thanks,

Michael
XE 285  1205 (Myrtle)
Start: 8/1/2013
Finish: 5/24/2014
Arrived home: 10/11/2014

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