HELLO EVERYBODY HELP WITH MY RADIO

[Antoruz]

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 

[Bosi72]

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 !

 

 

[Jabiru7252]

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. 

[Antoruz]

Thank you Jaribu7252 and Bosi72 I will check those points and thanks for the link 

[Yenn]

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?

[Jabiru7252]

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.

[old man emu]

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.

[Jabiru7252]

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. 

[Blueadventures]

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.

[RFguy]

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

[Antoruz]

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

[cscotthendry]

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.

[Antoruz]

Ok thank you for the tip 

[old man emu]

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?

[cscotthendry]

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.

[RFguy]

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.