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Grounding noise when transmitting

AJ85WA

AJ85WA

Well Known Member
Hi Guys

I need some help please.

Radio is MGL V6 with delta pop antenna.

The intercom and receiving of transmissions works great. But when I press the PTT switch i can hear anything touching the fuselage, like say tapping my fingers on the fuselage, or locking the canopy etc.

I have:

1. confirmed with meter that all headset, mics, music input jacks are isolated from the air frame. (all wires are shielded)

2. ALL grounds(mic's, headsets,PTT,music input etc) connect to the radio and then a single ground goes from the radio to the firewall ground

3. I have installed a noise filter from the alternator P-lead to the engine ground, but don't think it is related because it is not that kind of sound.

4. When the engine is running the noise increases with RPM(only with PTT held down), I have switched off the alternator, swapped between L and R mag and all other equipment is turned off?

5. I think it only happens when pressing PTT to freq above 117.0? I will have to confirm this.

Any help or input would be greatly appreciated. Im kinda stuck on this issue. I have not tested the antenna with SWL meter, could this be the problem?

Thanks in advance
AJ
 
Vogad

Hi Aerhed

Vogad is MED (5)
Mic level is -6

I have played around with all vogad levels and turned the mic gain down all the way, it does improve but it makes my communications talking very hard as I need to speak real loud.

The only way I could get it slightly better was to set the PTT to VOX, as the always HOT setting is unusable.

Thanks
AJ
 
What headset are you using AJ? Lightspeed Zulu, if yes drop the gain on the headset so you bring the V6 gain up a bit. The gain adjuster is a small trim pot under the windsock.
You shouldn't need -6, somewhere between 0 and -2 for a noisy aeroplane.

Go into the radio menu and turn on the Mic Filter Bandpass as well

Also try the VOGAD at High.

Ryan
 
No ANR headset

Hi Ryan

I am not using a ANR headset, just using a standard headset for now as recommended by MGL until I can get it to perform as it should, then I will switch to my ANR set as it is much worst with ANR.

I have played with Vogad HI and also Bandpass filter on or off and they don't seem to make any difference to the issue?

any idea why this only happens when PTT is pressed?
 
Waiting on reply

I have contacted MGL and awaiting a reply.

I was just hoping somebody on VAF might have had a similar problem with radios and could provide some input or things to test.

Thanks for all the replies already

AJ
 
This weekend.

Going up to the Hangar this weekend, weather is looking real bad so will give me lots of time for troubleshooting.

Any pointers of where to start looking?
Anybody?
 
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