Interference with Microair M760 radios

[jaba-who]

I have intermittently had problems with my set up in my jabiru J430. I have a D 180 flitedeck and two M760 Microair VHF radios with a four place intercom. Intermittently I get horrible interference through the radios ONLY on transmit. Receive is fine. When I transmit, the loud interference disrupts the output signal that other people can't understand the transmission at all.

If I turn the Dynon off the problem stops. Wierdly, changing radios sometimes fixes the problem for a few minutes and then it recurrs on the new radio. A number of times every was fine for about ten minutes. All worked till I finished my run up and the suddenly went bad. Sometimes the problem starts off only on one frequency, for a few minutes and another is fine, then suddenly occurs on the "good" frequency and then covers all frequencies - till I turn off the dynon then its fixed.

It is an intermittent problem and multiple attempts at rerouting wires shielding cables etc seems to work for a while (or maybe it just coincidentally goes away) then it recurrs at seemingly random times.

Anyone had problems like this? Any ideas on a fix?

Jaba-who

 

[DBRV10]

Where are you?

The early D10's gave trouble with the hash in the background and was impossible to squelch out in some frequency ranges.......... but this is not your problem.

If you are around Brisbane or can get here I can have a look at it for you. Its most likely a grounding issue. Dynon may like to comment and help.

Not sure Jabiru have the kind of technical support for this.

Cheers!

DB

 

[jaba-who]

Hi David,

I am in Cairns so it's a bit far to see you. Since posting the question I have spoken to one Microair tech who gave some non-specific adivice - turn back the mic gain on the radios and add some ferrite beads on all the cables particularly the radio antenae cables.

But yesterday I was told about another builder with same problem and spoke to him last night. Seems Microair actually know about the problem, have issued specific bulletins to avionics people round Australia and my local fix-it people (Australian Avionics) know about and have fixed his radio. Apparently it was more than just winding back the mic gain - involved some internal tinkering. But was done at no cost to the owner, presumably the cost (which was $162) is paid by Microair. So it seems to be an issue with the radios, rather than the Dynon.

What annoys me is the Microair Tech I spoke to didn't know about the issue. As I have found when dealing with them and other companies as well, that often the information is there, but not everyone who works there knows about it.. You have to ring several times and specifically ask to talk to different people each time till you find the guy who knows. :-[ :-/

Anyway, I will get onto Aust Avionics on Monday and get them to have a look at them.

Cheers

 

[DBRV10]

Well like all useful information...share it round, let us know how you go!

 

[jaba-who]

Nothing useful to report. Australian Avionics turned out to be not helpful. Seemed to not know what they actually did on the other Microair radio - not letting on at least. Maybe they just turned the mic gain back (and charged $162 dollars for it!)

Said I would have to talk to Microair which I already did.

So I have turned back the mic gain (simple screw driver through hole in side of box and turn - definitely not $162 worth of skill on my part) put ferrite beads on every cable coming into and out of radios, intercoms and some of dynon leads. Rerouted some of wires to seperate the power leads, dynon leads and radio leads from each other as much as possible.


I will take it for a test run on the weekend and see what happens.