Antoruz Posted January 20 Share Posted January 20 Hello everyone Ask if someone can help me with my next problem I have an MGL V6 radio installed in my ELA 07 gyrocopter with Rotax 914 engine and I use Flycom helmets The problem I have is that when they speak to me I hear a buzz in the reception I thought it was the gasoline pumps but when I turn off the engine and leave the electric pumps on, the buzz stops, the noise is coming in when they call me or when I listen to the ATIs I already checked all the ground ok antenna ok Also I put another radio with its harness and the same thing happens The interference is being generated by the engine when it is on, has this happened to someone? THANKS FOR YOUR HELP ANTONIO Link to post Share on other sites
Bosi72 Posted January 20 Share Posted January 20 I would try first with cleaning all contact points, checking shields in ignition system. Check grounding. Corroded contacts may cause arcing and interference. If above doesn't help, try ferrite chokes eg. http://www.microair.com.au/admin/uploads/RFInterferenceuseofferrites.pdf It's a work that needs investigation, good luck ! Link to post Share on other sites
Jabiru7252 Posted January 20 Share Posted January 20 Sounds like ignition noise. Disconnect the antenna to the radio. If the noise is still there, it's coming through the power lead. You'll need an inline choke fitted. I know nothing about Rotax engines but I would assume suppressed spark plug leads etc. are fitted. In cars, a suppressor capacitor was fitted to the ignition coil to stop interference. Something similar would apply to the Rotax engine I'm sure. As Bosi72 suggests, make sure all radio wiring and high tension (plugs, coils, magnetos etc.) wiring/connections are good. 3 Link to post Share on other sites
Antoruz Posted January 21 Author Share Posted January 21 Thank you Jaribu7252 and Bosi72 I will check those points and thanks for the link Link to post Share on other sites
Yenn Posted January 21 Share Posted January 21 Be very careful. If you disconnect the antenna do NOT transmit, keep your finger off the PTT, or you could damage the radio. Sounds like ignition noise, does it vary with rpm? Link to post Share on other sites
Jabiru7252 Posted January 21 Share Posted January 21 Good point Yenn re transmitting with no antenna - however a decent radio will know if that's the case an not try to deliver power up the coax. Link to post Share on other sites
old man emu Posted January 21 Share Posted January 21 45 minutes ago, Jabiru7252 said: however a decent radio will know if that's the case an not try to deliver power up the coax. And M'Lord, that's when the radio fully complied with Murphy's Law. Link to post Share on other sites
Jabiru7252 Posted January 21 Share Posted January 21 Duh? Back in the day, years ago, I had worked on a few transmitters that would 'sniff' the RF at the output and feed that back to a simple circuit that biased off the RF power transistor if things were wrong. It's pretty simple to implement, a diode or two, some resisters and a capacitor or two. These days, I look at the guts of a modern radio and it's two or three big chips and twelve million tiny, tiny things that are apparently resistors, capacitors and inductors. Most of the 'smarts' are in the big chips as firmware. Bring back transceivers that are as big as shoe boxes, weigh 10 kilos and hum quietly and I'd probably be able to fix it. 1 Link to post Share on other sites
Blueadventures Posted January 21 Share Posted January 21 On 20/01/2021 at 2:32 PM, Antoruz said: Hello everyone Ask if someone can help me with my next problem I have an MGL V6 radio installed in my ELA 07 gyrocopter with Rotax 914 engine and I use Flycom helmets The problem I have is that when they speak to me I hear a buzz in the reception I thought it was the gasoline pumps but when I turn off the engine and leave the electric pumps on, the buzz stops, the noise is coming in when they call me or when I listen to the ATIs I already checked all the ground ok antenna ok Also I put another radio with its harness and the same thing happens The interference is being generated by the engine when it is on, has this happened to someone? THANKS FOR YOUR HELP ANTONIO If you don’t have a 22,000 capacitor in your circuit try fitting one. Refer Rotax wiring diagram where to fit. A mate with a magni 22 had similar noise and the capacitor cleaned up the noise. Link to post Share on other sites
RFguy Posted January 21 Share Posted January 21 (edited) 22,000 uF cap wont help with radio noise if it is RADIATED. large electrolytic caps do not work at radio frequencies. It MAY if it is conducted and low frequency noise. can you post a short sound file of what it sounds like ? Edited January 21 by RFguy Link to post Share on other sites
Antoruz Posted January 22 Author Share Posted January 22 Hello,and thanks for all your help I already checked the radio, remove the usb charger and confirmed the noise comes from the motor when it accelerates the buzz increases and vice versa when decelerating the noise decreases I will have to check all the ground connections Link to post Share on other sites
cscotthendry Posted January 22 Share Posted January 22 Check, as Mike suggested, whether you have a large filter capacitor connected to your engine's voltage regulator. Look in the Rotax documentation in the electrical circuit diagrams. The Rotax charging system is notorious for generating electrical noise and the capacitor helps reduce it somewhat. Also, you should dig into all the negative return wires from everything electrical on your aircraft. All of the negative return wires MUST be returned to ONE common point. The system must not rely on frame returns to the negative of the electrical system as is done in cars. I repeat, the negative return of every electrical device MUST be connected to only ONE point DIRECTLY. Not doing this is usually the worst source of electrical noise in audio and radio equipment. 1 2 Link to post Share on other sites
Antoruz Posted January 22 Author Share Posted January 22 Ok thank you for the tip Link to post Share on other sites
old man emu Posted January 22 Share Posted January 22 4 hours ago, cscotthendry said: Not doing this is usually the worst source of electrical noise in audio and radio equipment. As an aside, if the airframe was used as the conduit to completed the circuit, wouldn't that set up a magnetic field that would affect a compass? I know that such effect can be accounted for by doing a compass swing, but you have to have a reason for doing the swing. The first reason is obviously the magnetic effects of the airframe, engine and other components, but are the effects of electrical current flow another? Link to post Share on other sites
cscotthendry Posted January 24 Share Posted January 24 On 23/01/2021 at 9:35 AM, old man emu said: As an aside, if the airframe was used as the conduit to completed the circuit, wouldn't that set up a magnetic field that would affect a compass? I know that such effect can be accounted for by doing a compass swing, but you have to have a reason for doing the swing. The first reason is obviously the magnetic effects of the airframe, engine and other components, but are the effects of electrical current flow another? That's a very interesting question and I don't have an answer for it. I think it's possible that the currents might cause EM fields that could affect the compass. Link to post Share on other sites
RFguy Posted January 24 Share Posted January 24 On 23/01/2021 at 10:35 AM, old man emu said: As an aside, if the airframe was used as the conduit to completed the circuit, wouldn't that set up a magnetic field that would affect a compass? I know that such effect can be accounted for by doing a compass swing, but you have to have a reason for doing the swing. The first reason is obviously the magnetic effects of the airframe, engine and other components, but are the effects of electrical current flow another? No, not for this scenario. Link to post Share on other sites
dan tonner Posted April 13 Share Posted April 13 I bought and installed an MGL V6 in my Rotax powered Savannah in 2012. Great product with even greater product support. I was in touch with MGL Avionics in Torrance California for installation and operational issues (my fault, not theirs) and got great product support right from the horse's mouth - so to speak. I believe Michigan Avionics is now doing much of the product support for MGL equipment and they oversee a "Customer Support Portal" you can join from their website. www.michiganavionics.com That being said, my "go to" guy was Matt Liknaitzky at MGL Avionics in Torrance, California. A call from Mexico won't break the bank (424) 358-4510 and if Matt can't help you, he can steer you to where you can get it. www.mglavionicsusa.com is their website. FWIW: in my case, all engine-related radio transmission/reception noise was eliminated by properly grounding one end of the wire sheath covering the generator wires and the charging wires coming from the stator and going to the ignition modules and the rectifier/regulator, respectively. Stay safe; fly safely. CanadaDan Link to post Share on other sites
IBob Posted April 13 Share Posted April 13 7 minutes ago, dan tonner said: FWIW: in my case, all engine-related radio transmission/reception noise was eliminated by properly grounding one end of the wire sheath covering the generator wires and the charging wires coming from the stator and going to the ignition modules and the rectifier/regulator, respectively. Thanks, Dan. That's a useful bit of info, and something else to check. Am currently circling a problem of radio noise on reception that only occurs when at full power, and does not occur at all at normal cruise settings. So far I inspected and tidied up all the plug leads, spacing them wherever possible from the metalwork, then ground run up to 4500RPM (the brakes/tires won't hold beyond that) with reduced squelch to check for ignition noise.....but I have yet to check at full power. I have also sourced but not yet fitted a 12V power filter: I doubt this is the problem, but these are the easy steps. I was also advised to turn down the mike gain on my Zulu headset/s, but that created problems where the radio wasn't picking up reliably from the mic. I wish I had a clearer idea of how all this works: back in the day my work was troubleshooting mainframe computers, and while I am certainly rusty now, my instinct is to proceed in a logical manner, rather than just taking a number of stabs at it....( Link to post Share on other sites
Kyle Communications Posted April 13 Share Posted April 13 Bob Your turn the mic gain down on the mic element then you have to turn up the internal mic audio on the radio. On both my Lightspeeds the mic gain was almost totally off to get really good performance...when I adjusted the mic element it was orginally set from new about just over half way which was way too much. Its a balancing act but you only want your voice to be picked up. Your mic on your headset should be sitting about 2mm from your lips...no further out this keeps the ambient noise especially at high rpm away from the mic as your voice level will be the only thing it should be hearing..also your Vox adjutment will come into this as well. You may need to increase the vox adjustment Link to post Share on other sites
IBob Posted April 13 Share Posted April 13 Hi Mark, thanks for that. I was aware that the mic needs to be as close as possible to the lips, also that the mic needs to be turned to face the lips (this can lose alignment over time, and is not always obvious with the foam mic cover on...but it's easy to check by feel.) My Zulu mic gain settings were both at 12oclock, or just under half. The difficulty I struck was that once I turned them down to any degree from there, no amount of boosting of the mic audio on the radio would reliably pick them up. It occurred to me later that perhaps parameter adjustments in the radio are not immediately actioned: it would be nice to know. In the end, I just put the radio back to factory settings, with the Zulus turned back just a bit to approx 11oclock. I don't yet know if this has made any improvement, I need incoming traffic on takeoff or hard climb to know. If there is no improvement, I will try all this again... Link to post Share on other sites
IBob Posted April 13 Share Posted April 13 Mark, what is the Vox adjustment you refer to? I can see no reference to that in the driving instructions........... Link to post Share on other sites
Kyle Communications Posted April 13 Share Posted April 13 I will look in the manual Vox is the sidetone audio pickup level. Thats a good indicator of what level you should be using as it is the same audio (and background) level that goes out when you hit the PTT button Link to post Share on other sites
Kyle Communications Posted April 13 Share Posted April 13 Try the Intsqh Thats the vox tripping for the intercom that will also tell you your audio out level quite a lot if you ahve a mate beside you..he will hear how much noise is in the cockpit in the background and that will allow you to adjust the internal micaudio level Its a adjustment you need to play with..its like running a pool at home its a balance of salt and chlorine and PH to get the levels you want. I have a new MGL V16 radio here and its a digital version it also has issues that are caused by all of the adjustments and how you do them but when you get the balance right between mic element audio level the internal radio mic gain etc it sounds really good on transmission 1 Link to post Share on other sites
IBob Posted April 13 Share Posted April 13 Okay. The Xcom has among it's main Mode options: SIDEVOL (sidetone) INTVOL and INTSQH (intercom volume and squelch) Then among the Setup Options (which are accessed differently than the Mode options) it has: GAIN (adjusts mic gain The manual says GAIN should only be adjusted by a technician, as transceiver performance will be affected. I was adjusting the Zulu mic gain down, and trying to offset that by adjusting the Xcom GAIN up. What I should add is that the Zulu/Xcom combination has worked just fine out of the box, except for this overlay of hash at full power. In all other situations both transmit and receive are clean and clear. Link to post Share on other sites
IBob Posted April 13 Share Posted April 13 Okay, I will certainly try the INTSQH. I guess the part I am not understanding here is, if this is noise coming in my mic, why do I not hear this noise until I have incoming radio traffic? Or, put another way, if noise into the mic and mic gain and Xcom mic vol are great enough to trigger the comms, would I not be hearing this noise all the time??? Link to post Share on other sites
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