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Kitfox with radio full of static

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debrun26(at)juno.com
Guest

Posted: Mon Oct 22, 2007 10:04 pm Post subject: Kitfox with radio full of static

I think I'm going to have to trade my Icom A22 hand held for an A200.  Way too much static at 3000rpm and above.  Any ideas what is causing this and how to get rid of it?  I really don't have the money for a panel mount.  Also, what's the cheapest way to get some wing covers for my series5?  The snow is starting to fly... Yikes!         Layne,  Anchorage, Alaska     



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Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Tue Oct 23, 2007 12:28 am Post subject: Kitfox with radio full of static

 	  Quote: 	
		   From: debrun26(at)juno.com

Way too much static at 3000rpm and above.


	


Hello Layne from Anchorage - who happens to be at roughtly the same latitude as mine; only that we have, in Norway, the Gulfstream current to bring us a slightly milder climate along the coast. 



Radio statics, also called RFI (Radio Frenquency Interferences) has keep generations of radio amateurs sleepless at night. They may come from almost anything, even the slowly rotating propeller shaft of my sailboat when sailing!



In our planes, finding their source may be started by finding if the static increases in pitch with the RPM. It is then certain that it comes from the ignition system and/or the engine. Next is to find if it is carried by air or through the power supply. If you use a hand-held radio with only an internal battery, do you still hear the statics? Then it is airborne. Shielding and/or moving the antenna at another place may be the only solution. If it is not airborne, then it comes to your radio by the power supply line. In that case, you should consider using ferrite coils on the line, or condensers between them. You will have to experiment, my friend.



Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200

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Kitfox 3 - Jabiru 2200

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Oct 23, 2007 5:37 am Post subject: Kitfox with radio full of static

What Michel said and....



I would like to  know a few other things though.  What kind of engine are you using, what  kind of spark plugs and spark plug caps.  Is the interference strong enough  to open the squelch on your radio or do you only hear it on incoming  signals.  does it make any difference to the static whether the radio is in  the left or right seat?  Finally do radios receiving your signal hear the  hash?



The reason I ask this is because the 2 stroke Rotax engines are a  bit odd ball.  The later ones with the electronic ignitions require the use  of *both* resistor plugs and resistor  caps. 



The plugs are BR8ES.  This causes a bit of a problem as  NGK makes two BR8ES plugs one has an aluminium screw on top and is gapped around  .030" or wider.  The BR8ES plugs coming from Rotax have solid steel heads  on them and are gapped .018"  for the extra few dollars It is better to get  those plugs.  First the steel tops won't break down and cause arcing inside  the caps which will eventually short out the caps.



About the caps there  are maroon and black caps from NGK and I think you can get metallic caps from  other suppliers  I think the only difference in them is the colour.   What is important about the is that they should have about 5K Ohms resistance  across the inside of the cap.(between where the wire goes in and where the plug  clips on.  To make it difficult to remember, the centre electrode of the  spark plug also has a resistance of about 5 K Ohms.  If those resistances  are shorted out you will get static, I mean STATIC!



To get to my pet  peeve... Grounding.  Michaels ships are hard enough to keep good grounds  on, salt can do strange things to metal, airplanes can be a lot more  difficult.  You can get an alternator wine which will get higher and louder  as the RPM goes up for many reasons. 



Check the ground braid that  jumps across the engine mount.  This should be a honkin' big mother of a  wire, well, maybe not quite so big as the starter cable but big enough to  be noticeable. The contacts of that wire should be nice and shiny clean under  the mounting nuts/bolts on both ends.  A bit of crud in either those  connections can cause RFI.  While you are checking that wire give it a  gentle tug.  The terminals on these wires are  generally crimped on and sometimes, not too often, you will get a bad  crimp.  If the wire comes out of the terminal clean it off and crimp on a  new terminal.



Check the mount for the voltage  regulator.  Most of those regulators should be mounted to a good  ground.  Paint or a little rust behind the regulator can cause the RFI and  interference on the DC wires.



Finally check that there is a really good  grounding strap from the frame of the plane to the instrument panel if your  instruments are grounded to the panel.



If you are using an external  antenna on your radio, I do, then the external antenna should have a ground  plane of about 20+ inches under the antenna.  Get someone to do a SWR test  on your antenna from the BNC connector you attach to your radio.  That  ensures your antenna has the best tune for the com band.  Also look for any  nicks, bends or kinks in the coax there is a chance they will cause you  RFI.



 

[img]cid:906173613(at)23102007-31DB[/img]  

 Noel Loveys, RPP, AME intern

 Campbellton, Newfoundland, 

 Canada

 Kitfox Mod III-A, 582, B box, Ivo IFA

 Aerocet 1100s

 noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)

 

 

 

  

 

 



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Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

eskflyer

Joined: 24 May 2007
Posts: 44
Location: AK

Posted: Tue Oct 23, 2007 7:42 am Post subject: Re: Kitfox with radio full of static

Or make it simple and go down to the NAPA store and get 2 inline noise filters and put one on the hot wire feeding the panel and one on the hot wire feeding the radio . I can almost guarantee it will cure all your radio noise problems . They only cost a few dollars and take a few minutes to install .

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John Perry
Kitfox 2 N718PD
582 cbox 2:62-1 IVO IFA
1220 Full Lotus

debrun26(at)juno.com
Guest

Posted: Tue Oct 23, 2007 10:19 pm Post subject: Kitfox with radio full of static

Noel & Michel~     Thanks for the help with the static radio problem.  My power plant is a Sooby EA81 engine.  The interference starts at 3000 rpm but it's clear to those listening to me.  I have an external antenna mounted behind the turtle deck.  I'll check all your suggestions and see if I can get to hear the tower better.   Thanks,   Layne  Series 5 EA81 Sooby     



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Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Oct 24, 2007 3:49 am Post subject: Kitfox with radio full of static

Are you operating the radio  from the aircraft 12V system?  Do you hear the static on  receive?

  

 Noel

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Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Oct 24, 2007 4:04 am Post subject: Kitfox with radio full of static

I just thought of more sources  of static.  

 First is the ECU for your  Subie...  the case should be very well grounded  ( my old beef)  Although I seriously doubt that's your problem.

  

 Next is the possibility of a  cracked ignition coil.  It is possible that one of your coils is breaking  down and arcing above 3000 rpm.  

  

 Finally check out your  alternator.  I can't say why, but what I would be looking for is worn out  brushes, springs or any puffy looking capacitors that you may find associated  with your charging system.  Check for dark spots on the slip rings of the  alternator.  While you are at it check out the connections from your  voltage regulator to your field coil.

  

 Being mounted outside your  antenna will be using your frame as a ground plane.  Assuming the  mount was cleaned before the antenna was installed there probably won't be any  problem there.  I'd still get the SWR checked as part of the annual  though.  It only takes a few seconds especially if you have a noise bridge  ( piece of technical equipment)

  

 Too bad we can't hear the type  of hash you are getting.

  

 Noel

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Wed Oct 24, 2007 5:15 am Post subject: Kitfox with radio full of static

 	  Quote: 	
		   From: debrun26(at)juno.com

 Sent: 2007-10-24 08:17:03 CEST

 To: kitfox-list(at)matronics.com

 Subject: RE: Kitfox with radio full of static

 Noel & Michel~     Thanks for the help with the static radio problem.  My power plant is a Sooby EA81 engine.  The interference starts at 3000 rpm but it's clear to those listening to me.  I have an external antenna mounted behind the turtle deck.  I'll check all your suggestions and see if I can get to hear the tower better.   Thanks,   Layne  

Layne, when I had a Rotax 582, I also experienced statics at and above a certain RPM. I then moved the regulator from nearby the radio to ahead of the firewall. RFI were gone! The reason was: The regulator is a switch-mode electronic one. When the voltage exceed say 14 V, it chops electronically part of it to keep it at that level. What I could hear was the 'chopping.' Distance and firewall between the two ... et voila!

It is probably not your case but ... that's all I can think of. Good luck.

Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200

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Kitfox 3 - Jabiru 2200

apeterchristensen(at)sbcg
Guest

Posted: Wed Oct 24, 2007 9:22 am Post subject: Kitfox with radio full of static

Layne,

  

 What are the advantages of a Sooby EA81 engine?  Are they reliable?   Are they easy to maintain or do you have to be a magician to keep them  running?  Would you recommend that engine?

  

 Pete

 [quote]   ---

debrun26(at)juno.com
Guest

Posted: Thu Oct 25, 2007 3:01 pm Post subject: Kitfox with radio full of static

Pete,    I'm no mechanic and haven't had my KF long but you should get ahold of Peter Graechen on the list.  He really knows his stuffff!!!!  I was having some technical problems that I was trying to figure out and for some reason they fixed themselves.  I don't know if you can get the NSI EA81 engine anymore since NSI went out of business years ago.  I'm a student pilot learning in my own kitfox so I don't have much experience.  I went up the other day with a supercub bush pilot and he said my plane out performed his in everything but cargo capasity.  We were crusing at 100mph... 4.5gal/ hr, climbing at 900fpm with full tanks and 400lbs of people.  Did lots of stalls, takeoffs, 60 degree turns etc...  The only thing he didn't like about my plane was that he wanted me to get rid of the wheel pants and put some 26 inch bush wheels on.   Hope this helps...   Layne   

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