Radio Interference

[Guest veldthui]

Our plane had an ICOM IC-A200 which had plenty of noise coming through often. It was different by frequency in that some were worse than others. It was fine when there was a transmission but when no apparent transmissions we got noise. The CSU certainly triggered it going from corse to fine but not the other way. At times when it was on manual not moving it was still doing it.

 

Thinking it was the squelch (the A200 does not have a readily adjustable squelch) the radio has been upgraded to a ICOM IC-A210. While it has reduced the noise it is still present at times.

 

There does not appear to be an earth strap from the motor to the frame. Will adding one help?

 

Also as it is most certainly the CSU making most of the noise how do I go about sheilding the wires to stop this?

 

Thanks.

 

John Veldthuis

 

 

[Guest Nelson Smith]

Hi John,

 

When we upgraded from A200 to A210,it was grief +.The transponder aerial was situated too close to the A210 radio.I moved the trans. aerial 1.5 metres aft and the noise disappeared.Yet the A200 was quite happy with the original location of the aerial.

 

What is a csu (pardon my ignorance)

 

Nelson

 

p.s. The A210 is a top radio now

 

 

[Guest brentc]

CSU - Constant Speed Unit for the prop pitch adjustment

 

 

[Yenn]

My A200 had similar problems, sounded like ignition from the Jab 2.2, but i awapped another identical radio and there was no noise.

 

The local dealers said it was something to do with no squelch on the sideband or something and it is now at Icom for fixing. I think they may be holding it until the warranty runs out, by the time it takes to come back.

 

 

[Guest veldthui]

Thanks, Upgraded from the A200 to the A210 and so far it is better but still noise from the CSU coming through. Was wondering how to shield it easily.

 

For our A200 it was vertainly the squelch and it only has a manual adjustment but the A210 has adjustment in a menu and it is set at 7 at present. The range is -10 to 10. At 10 the noise is still there from the CSU and it triggers the Rx.

 

 

[Guest Nelson Smith]

Hi Veldthui,

 

I would think that a suppressor on the csu motor would be the fix.Even though the A200 wasn't prone to the noise

 

Nelson

 

 

[Guest Maj Millard]

Suppressor on the CSU motor might do the trick...or ...check location of antennas in relation to others and Transponder antenna, or you may be picking up the interferrence through your coax cable. If so you may have to upgrade that. See instalation mamual they usually recommend min coax cable standard Cheers Ross

 

 

[shafto]

Agreed with Maj Millard there, have a good look over the coax cables and check the terminations....Could be a braid thats frayed away from the connector.

 

Another thing to check is where the coax cable actually is loomed and how it is loomed, if it has been loomed into a loop too tight the braid/insulation will degrade and you will get feedback. Usually caused from over zealous zip tieing also just have a look where the coax runs could be as simple as that.

 

 

[sain]

You could also try adding a ferrite bead to the power cable for the radio - probably a good idea anyway. Cost is $3 for a pack of six at jaycar, which should leave enough left over to do somebody else's radio. Just thread the power cord through it, then hold in place with some heatshrink tubing. Put it in as close to the radio as you can manage.

 

Part here:

 

Ferrite Bead For EMI Suppression - Pk.6 - Jaycar Electronics

 

Mind you that will only help if the noise is coming down the power line. Test it out on the ground with the radio running from a seperate power supply (car battery should work). If you still get noise its more likely to be an antenna issue. Check out the coax at both connections - Any dodgy or loose connections will be a potential source of noise.