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smokey_bear_40220(at)yaho
Guest

Posted: Thu Nov 02, 2006 9:59 am Post subject: radio problem

Kirk/Noel,



Noel!  Good shot.  This is what I was thinking on my

origional post too.  Try the external antenna away

from the aircraft to see if it works.  Then with the

radio in the same place, move the antenna (2 people

reqd) toward the plane and see if it stops.  If so,

Noel is right.  As he said, install a well grounded

seperate antenna.



Maybe after all else is installed and properly

grounded the radio will work again on the origional

antenna.



If not, next guess?



Kurt S.



 	  Quote: 	
		   My guess is there has been a piece of something

 metal, not grounded about

 18-20" long in your cockpit that is acting as a

 parasitic element and

 causing a high SWR on your antenna.  If you can find

 that ( probably wire

 but could be something like a windshield support )

 ground it.  Circuits in

 your radio are protecting your output transistors by

 shutting the radio

 down.  you could try an external antenna... just

 make sure the base of the antenna is well grounded.


	


 	  Quote: 	
		   Noel


	




 

Get your email and see which of your friends are online - Right on the New Yahoo.com 

(http://www.yahoo.com/preview)

Float Flyr

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

Posted: Thu Nov 02, 2006 10:31 am Post subject: radio problem

No the transponder and encoder  are both grounded to the frame of the airplane.  

 

Something in the plane is causing your outgoing  transmission to be reflected back into your antenna so the transmitter works  harder to put out a signal. Another circuit in your radio monitors how hard the  transmitter section is working.  It tells the transmitter it's working  too hard and and may die if it continues to work too hard.....your transmitter  shuts down (transmitters usually do what they are told).

  

 You have to find out how  the signal is getting back into the output circuit.  There are basically  two ways.   

 1. Something in your plane is  resonating with your out going signal and reflecting it back into the antenna  effectively creating an RF dam in your antenna and just like a water  dam it causes pressure to build up behind the dam ( antenna ) In this case the  pressure causes the finals of your transmitter to work harder and heat up to the  point where protection circuits shut it down.  The disconnected wires of  your transponder coiled up under your dash could be the cause.  If they  are, the problem will disappear as soon as the wires are installed and trimmed  to length.

  

 2. Radio Frequency waves (RF)  some how is being reflected by something in your cockpit and is able to  penetrate the circuits of your radio.  this is known as RF feed back.   Some times you will hear a squeal as the feed back starts to gain in  intensity.  Radios are designed to be protected from RF feedback but  sometimes bonding wires between circuit boards do get broken and problems with  RF feed back arise.  If you try a remote ( external ) antenna more than 3'  from your radio and the problem goes away RF feed back may have been your  problem and an external antenna the easiest fix.

  

 

Noel 

Best  of luck! 

  [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

kirkhull(at)kc.rr.com
Guest

Posted: Thu Nov 02, 2006 10:56 am Post subject: radio problem

THANKS I HAVE SOME THINGS TO TRY  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Noel Loveys

 Sent: Thursday, November 02, 2006 12:31 PM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

     

No the transponder and encoder are both grounded to the frame of the airplane.    

    



 Something in the plane is causing your outgoing transmission to be reflected back into your antenna so the transmitter works harder to put out a signal. Another circuit in your radio monitors how hard the transmitter section is working.  It tells the transmitter it's working too hard and and may die if it continues to work too hard.....your transmitter shuts down (transmitters usually do what they are told).  

    

   

    

You have to find out how the signal is getting back into the output circuit.  There are basically two ways.    

    

1. Something in your plane is resonating with your out going signal and reflecting it back into the antenna effectively creating an RF dam in your antenna and just like a water dam it causes pressure to build up behind the dam ( antenna ) In this case the pressure causes the finals of your transmitter to work harder and heat up to the point where protection circuits shut it down.  The disconnected wires of your transponder coiled up under your dash could be the cause.  If they are, the problem will disappear as soon as the wires are installed and trimmed to length.  

    

   

    

2. Radio Frequency waves (RF) some how is being reflected by something in your cockpit and is able to penetrate the circuits of your radio.  this is known as RF feed back.  Some times you will hear a squeal as the feed back starts to gain in intensity.  Radios are designed to be protected from RF feedback but sometimes bonding wires between circuit boards do get broken and problems with RF feed back arise.  If you try a remote ( external ) antenna more than 3' from your radio and the problem goes away RF feed back may have been your problem and an external antenna the easiest fix.  

    

   

  

Noel  

Best of luck!  

   [quote]  

--

temco(at)telusplanet.net
Guest

Posted: Thu Nov 02, 2006 1:35 pm Post subject: radio problem

Kirk  

   

Assuming that you have eliminated your antenna as the cause. Have you done an antenna VSWR from in the acrft using your problem radio??  Do this --- wrap the entire radio in normal household aluminum and ground the whole package and see if it still fails.  You can push the press to talk through the foil wrap. Make sure that the entire handheld is wrapped and tightly twisted at the antenna cable and DC power lead ins. This is to prove whether the interference is airborne (radiated) or whether it is coming in on the DC power leads??? I am assuming you are hooked to your 12VDC arcft system? If it’s radiated or DC power interference ---- then shut off all other electrical and experiment by turning additional electronic/electrical systems on --- one at a time till you hit on the offending culprit    

   

In my view there are only 3 things that can cause this problem. !. Antenna, 2. Radiated interference 3 DC power source interference.  

   

Of course this being Halloween any of a thousand other gremlins could be in your unit.  

   

Regards --- Ted  

   

   

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of kirk hull

 Sent: November 2, 2006 5:54 AM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

   

I have been using the same antenna inside and outside the aircraft.  If I hold down the transmit button outside the aircraft it will transmit then if I move the radio toward the aircraft it will stop transmitting at about 6 inches of any metal part of the plane.  It works fine in the car.  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Ted Palamarek

 Sent: Wednesday, November 01, 2006 5:54 PM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

   

Kirk  

   

First thing to check is your antenna. It seems like you have an open or short and your VSWR has gone west on you. This will cause your TX final in the set to heat and turn off.  If it works okay out of the plane on a different antenna then check you antenna for a short or open with a VOM  

   

Hope this helps  

   

Ted  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of kirk hull

 Sent: November 1, 2006 3:43 PM

 To: kitfox-list(at)matronics.com

 Subject: radio problem  

  

   

I have a strange radio problem.  I am using an Icom A4 it works great out of the airplane but will only transmit for about 5 sec when it is within 6 inches of any metal part of the airplane.  

   

It use to work fine in the plane.  Many changes have been made to the plane  but I have no idea what is causing the problem.  Any Ideas?    	  Quote: 	
		     	
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kirkhull(at)kc.rr.com
Guest

Posted: Thu Nov 02, 2006 7:31 pm Post subject: radio problem

I am using only the radio with the antenna it came with.  No external power and nothing in the plane is turned on / engine off and master off  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Ted Palamarek

 Sent: Thursday, November 02, 2006 3:34 PM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

   

Kirk  

   

Assuming that you have eliminated your antenna as the cause. Have you done an antenna VSWR from in the acrft using your problem radio??  Do this --- wrap the entire radio in normal household aluminum and ground the whole package and see if it still fails.  You can push the press to talk through the foil wrap. Make sure that the entire handheld is wrapped and tightly twisted at the antenna cable and DC power lead ins. This is to prove whether the interference is airborne (radiated) or whether it is coming in on the DC power leads??? I am assuming you are hooked to your 12VDC arcft system? If it’s radiated or DC power interference ---- then shut off all other electrical and experiment by turning additional electronic/electrical systems on --- one at a time till you hit on the offending culprit    

   

In my view there are only 3 things that can cause this problem. !. Antenna, 2. Radiated interference 3 DC power source interference.  

   

Of course this being Halloween any of a thousand other gremlins could be in your unit.  

   

Regards --- Ted  

   

   

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of kirk hull

 Sent: November 2, 2006 5:54 AM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

   

I have been using the same antenna inside and outside the aircraft.  If I hold down the transmit button outside the aircraft it will transmit then if I move the radio toward the aircraft it will stop transmitting at about 6 inches of any metal part of the plane.  It works fine in the car.  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Ted Palamarek

 Sent: Wednesday, November 01, 2006 5:54 PM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

   

Kirk  

   

First thing to check is your antenna. It seems like you have an open or short and your VSWR has gone west on you. This will cause your TX final in the set to heat and turn off.  If it works okay out of the plane on a different antenna then check you antenna for a short or open with a VOM  

   

Hope this helps  

   

Ted  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of kirk hull

 Sent: November 1, 2006 3:43 PM

 To: kitfox-list(at)matronics.com

 Subject: radio problem  

  

   

I have a strange radio problem.  I am using an Icom A4 it works great out of the airplane but will only transmit for about 5 sec when it is within 6 inches of any metal part of the airplane.  

   

It use to work fine in the plane.  Many changes have been made to the plane  but I have no idea what is causing the problem.  Any Ideas?    	  Quote: 	
		     	
[/b]http://www.matronics.com/Navigator?Kitfox-List 	  Quote: 	
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        [quote][b]

temco(at)telusplanet.net
Guest

Posted: Thu Nov 02, 2006 8:13 pm Post subject: radio problem

Kirk  

   

Do I understand you correctly in that you are inside the airplane trying to transmit with the rubber duck antenna that came with the ICOM when the problem occurred??? If that is the case, the metal frame and other metal components may be acting as a screen or reradiating and causing a high VSWR and shutting down the TX power amplifier.  If the above is true, you need to use and external antenna fed with a coax to avoid that situation. This way you put the RF field outside the metal structure of the aircraft.  

   

I am a Ham Radio operator and operate my 2 meter rig out of my stucco garage. Of course being stucco there is mesh wire surrounding the garage (somewhat akin to the metal aircraft fuselage) and I have found that the placement of the antenna in the garage greatly affects the RF power out and the VSWR. The 2 meter frequency is just a little higher than the air to ground band.  

   

Ted  

   

    

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of kirk hull

 Sent: November 2, 2006 8:31 PM

 To: kitfox-list(at)matronics.com

 Subject: RE: radio problem  

  

   

I am using only the radio with the antenna it came with.  No external power and nothing in the plane is turned on / engine off and master off  

         

  

  

       [quote][b]

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Sat Nov 04, 2006 12:17 am Post subject: radio problem

On Nov 4, 2006, at 1:46 AM, Noel Loveys wrote:

 	  Quote: 	
		   Funny thing about compasses....  They are the first instrument your 

 plane

 should have ......  And the last one you will ever look at.


	


That is true, Noel. 

I also have problems to understand how a radio can disturb a compass, 

just as I have a problem to understand how a GPS can disturb a VHF 

radio. But I am old enough to know that 'impossible' is a word that 

doesn't exist and I follow the tread with attention.



Cheers,

Michel



do not archive

_________________
Kitfox 3 - Jabiru 2200

Float Flyr

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

Posted: Sat Nov 04, 2006 5:23 am Post subject: radio problem

It's not so much the radio as the steel case it's in.  Other things that can

happen is one of those magnetic screwdriver bits get left inside the case,

right under your compass.



As for the GPS RFI... That one I've seen on an early GPS.  The GPS receiver

is actually three beasts in one.  It's a sensitive micro wave radio receiver

with all the problems associated with high/multiple IF frequencies.  It's an

astoundingly accurate timer ( 1 step away from caesium ) and it's a mini

computer and we all know how RF noisy computers are!  You put something as

potentially noisy as that close to the IF circuits of your com and you will

get noise especially on the earlier models of GPS.



If you really want to see noise try placing an FM marine radio any where

close to a depth sounder!  Their amplitude of the "Ping" is so high it's

almost impossible to filter.  Larger ships put the actual sounder/transducer

in a remote location and only have a display routed to the helm.



As you say nothing is impossible.  I remember twenty years ago telling a

friend about hams sending colour pictures all around the world... He said

so.  My reply was that it was done through a 1KHZ window.  That put a

different wheel on the cart.  I can still remember him saying that's

impossible.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Sat Nov 04, 2006 7:57 am Post subject: radio problem

On Nov 4, 2006, at 2:23 PM, Noel Loveys wrote:

 	  Quote: 	
		   It's not so much the radio as the steel case it's in.


	


Yes, that is more understandable, Noel.



 	  Quote: 	
		   If you really want to see noise try placing an FM marine radio any 

 where

 close to a depth sounder!


	


Er ... my marine VHF radio and depth sounder are no more than a foot 

apart and I haven't noticed anything. But then, I am talking about the 

receiver, not the transducer that is at the lowest point of the hull.



 	  Quote: 	
		   I remember twenty years ago telling a friend about hams sending colour 

 pictures all around the world...


	


Slow-scan TV? Few people know all the weird things hams are doing, like 

moon bouncing and meteor scatters ... 



My only RFI, when sailing, was when I used the ham radio on the 20 

meters band, with 100 Watts output, which resulted in my GPS and 

Autohelm autopilot jamming. I use the isolated backstay as a long wire 

antenna.



Cheers,

Michel



do not archive

_________________
Kitfox 3 - Jabiru 2200

smokey_bear_40220(at)yaho
Guest

Posted: Sat Nov 04, 2006 9:42 pm Post subject: radio problem

--- Michel Verheughe <michel(at)online.no> wrote:



 	  Quote: 	
		   Slow-scan TV? Few people know all the weird things

 hams are doing, like 

 moon bouncing and meteor scatters ... 


	


If I remember correctly, NASA borrowed slow scan from

the Ham guys, who invented it.  NASA stayed with it

until the digital age for all their space pics.  But

slow scan, like KitFox's and our "improvements", are

home brew.  Many new ideas also come from model

builders.



We are the leaders, not the followers.  



Kurt S.



Do not archive

 

Get your email and see which of your friends are online - Right on the New Yahoo.com 

(http://www.yahoo.com/preview)

Rex Hefferan

Joined: 10 Jan 2006
Posts: 147
Location: Olney Springs, Colorado USA "NOT a Kitpig"

Posted: Sun Nov 05, 2006 2:31 pm Post subject: radio problem

Yes and don't forget many of the engineers are also Hams so they 

probably just transferred their hobby ideas into their work.

 Hey, do you think there's a market for micro air cargo carriers? I can 

see it now, Kitfoxes flying little packages to remote customers. 

Rex

Colorado

kurt schrader wrote:

 	  Quote: 	

--- Michel Verheughe <michel(at)online.no> wrote:

>Slow-scan TV? Few people know all the weird things

>hams are doing, like 

>moon bouncing and meteor scatters ... 

>    

>

If I remember correctly, NASA borrowed slow scan from

the Ham guys, who invented it.  NASA stayed with it

until the digital age for all their space pics.  But

slow scan, like KitFox's and our "improvements", are

home brew.  Many new ideas also come from model

builders.

We are the leaders, not the followers.  

Kurt S.

Do not archive

_________________
Rex
N740GP - M2/582
Colorado

smokey_bear_40220(at)yaho
Guest

Posted: Sun Nov 05, 2006 9:15 pm Post subject: radio problem

Cross fertilization is one of the main benefits of

this list.  That is how I ended up with a boat compass

and starter switch on my Fox.  The boat compass

adjusted out the bad magnetism of the panel area, and

the boat starter switch has a "push to prime" function

making that a one hand operation.  Learned it

here.....



I grew up with a 2 meter home made antenna on the roof

(as well as a few other bands) of a home made house. 

My father taught me to "git-er-done".



 	  Quote: 	
		  From this list I learned things that made my Fox

better and safer.  I truely believe people here have
	


saved lives thru prevention of costly mistakes and

honest sharing of lessons learned.



We are dreamers and sometimes get off track, but it

all seems to educate us for the better.  Like Lowell,

I try to read everything and I learn.  I may not have

the same engine, raido, etc, but a good idea often

comes from different sources.



We just need to keep it civil and real.



Starting with this subject "radio problem", a number

of well, and sometimes self educated people will toss

around ideas and get to the right answer eventually. 

But lets try not to confuse the answer.



I remember Don S. and his surging engine problem

costing him a bunch in time, money and frustration. 

If we could have been there and seen it happen just

once, many of us would have known it was the clutch

right off and saved Don a bunch.  For most people this

list does make the save.  Don S. is one of the hero's

in our favor, even if we didn't get it correct right

off for him, he has been there for us.



As with hangar talk, sometimes I have to walk away,

but I am right back here almost every day to learn...

-------------------------------------------------

Working for UPS, I used to fly Louisville, Omaha,

Cedar rapids, Louisville flights.  A Cessna 4xx would

race us to Cedar Rapids every night with half a dozen

boxes for us to haul out.  Sometimes it would get down

to only 2 boxes.  Eventually the 4xx was canceled, but

it showed that there was still business for the little

planes too.



UPS started as West Coast boys on bikes.  Now it hauls

6% of the US GNP.  Certainly "Flying FoxCars" isn't

beyond reality.  



Kurt S.  S-5 (my other plane)



Do not archive



--- GypsyBeeInnkeepers <hefferans(at)gmail.com> wrote:



 	  Quote: 	
		    Yes and don't forget many of the engineers are also

 Hams so they 

 probably just transferred their hobby ideas into

 their work.

  Hey, do you think there's a market for micro air

 cargo carriers? I can 

 see it now, Kitfoxes flying little packages to

 remote customers. 

 Rex

 Colorado

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