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Radio Interference
#11
you can see on the next videos what I have done to discover the problem with the MGL's
https://youtu.be/gu886YWcxYY

then I have use the following test setup to made investigations

   

I have connected the oscilloscope to the battery too and the next pic shows the interferences on the 12V bus
   
you can see a tension of 180mVpp and 255kHz, generated by the internal DC-DC converter.
   
To avoid that these interferences are passing to the 12V bus I have added a filter. I have used a coil(unknown value) and a capacitor (10uF).
First I have cuted the wire on the circuit board to insert the coil and then I have added the cap parallel to the 12V input.
   
after this intervention the interferences was droped to 20mVpp.
   
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#12
Used mostly on ultralights & experimentals with 2-stroke powerplants, surely it would improve their MGL products if the internal interference can be minimized. Wondering out loud if MGL would undertake this upgrade (for a fee) at the factory without us breaking open our gauges and voiding our warranties??

MGL REP following this thread? ???
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#13
It is also possible to add the filter into the Sub-D connector so you don't need to open the device
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#14
Big Grin For those of us desperate to achieve effective VHF communication, but are electronics challenged, would love to have you post photos & instructions on how to incoroprate the filter INTO the sub-D connector (when you have time).  And thank you for your research and expertise.

Andy
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#15
Got me re-reading "AeroElectric" the book by Bob Nuckolls - chapter 16 on EMF Noise. I understand the working of the Inductor/capacitor filter, plus Ground Loop a little better now. Recommended reading!
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#16
    [attachment=2376]     [attachment=2376]WARNING______I tried the noise filter that was suggested in the earlier post........... An inline power noise active suppression filter (Axxess AX-ANR1000) is installed between the Master Switch and the input to the Fuse Box to attempt to ensure a noiseless +12V power supply to the entire aircraft.

After about 25 minutes of running time the unit made a pop noise and the helicopter shut down. I had it installed as the prior post said to do it. There are only 3 wires from it to hook up, a ground, the positive power source and the power source coming thru the suppressor. I was on the ground when it shut everything down not in the air flying. I never got a chance to try using it with the radio. I wouldn't suggest using that noise suppressor hooked up thru the main power switch.
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#17
So, if I remember correctly, these engines won't run without the battery connected. Looks like this was a single point failure item. Perhaps if it was used only for the radio power? Glad you were on the ground when this happened.
Dave
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#18
(09-22-2015, 12:30 PM)Dave R. Wrote: So, if I remember correctly, these engines won't run without the battery connected.  Looks like this was a single point failure item. Perhaps if it was used only for the radio power?  Glad you were on the ground when this happened.
Dave

I use a ICOM A24 Handheld radio. I also tried covering the coils with copper tape which didn't seem to do a thing either. I have a lot of noise unless I turn the squelch up to 24. Thanks Skeeter, so was I .
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#19
Jim: glad your noise filter failure didn't lead to catastrophic failure. There has been reports online that the factory wiring instructions had been wrong. (Correct= GREEN to + supply, RED to + user, BLACK to ground) I had the chance to fly my XEL thus wired for 20 mins with no ill effect 3 weeks ago.

After all noise preventions taken as in previous post, net effect was disappointing. Still a lot of radio noise. Next step is to trace source of noise (alternator, antenna, instruments, ground loop, radio position).
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#20
    You would think that the red wire would have been the positive and the black the ground. The instructions it came with did show the red wire the source wire and the green wire the positive wire so it was connected correctly. Your test discovered it didn't solve the problem anyway so its been filed into the trash can.
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