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radio noise

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lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Tue Mar 06, 2007 11:55 am Post subject: radio noise

You may remember I was having problems with my radio having  lots of static with a new engine change. I received suggestions that I get a rf  capacitor to stop it. I was unable to do so without going on line and ordering  one. I generally have a bit of trouble buying something that I can't examine. (  we all have our quirks) One of the problems that I had with an earlier version  capacitor was that it screwed with my RPM's on my EIS. So I called the gal at  EIS and asked her about the problem. She told me to change to the gray wire out  of the rectifier, but that it would cost me the check for one of my mags. She  mentioned a RF choke from Radio Shack that should do the job of cutting out the  static interference. The numbers are 273-105 and 273-104. Look them up on the  Radio Shack web page. Most all the Radio Shack stores carry them unlike the  capacitor. The cost for both is under $15.00. They work by wrapping the wire  around one of the chokes and the other works by just passing the wire through  it. In a conversation with Roger Hankins, I found that the choke will eliminate  the necessity of matching your RG cable length to the antenna. I cannot tell you  any more about this aspect, perhaps Roger can clarify that.  

  

 The weather finally moderated enough to allow me to fly today,  so off into the wild blue I went with the wife giving me radio checks on the  ground. I am pleased to report that there was "minimal" static with the use of  these, and it APPEARS that the distance has been increased dramatically. I caped  appears, since there has been no exhaustive testing done. The only thing that I  can tell you is that before the chokes I could only talk to her from about 8  miles. This time there was no noticeable difference in quality at that distance.  Good enough for me, you can make your own deductions.

  

 I did have to remove the power wire to the 196 gps though. My  choke is placed on the main feed wire from the battery to the main power bar.  All the power originates there through the master switch. The GPS power wire  makes a static build up that culminates in a "pop", then builds again. Karen  can't hear it, but it is quite loud in my head phones. I will wrap the power  wire around a choke and see if that helps. If not then I guess I am going to  have to buy some stock in Delco batteries.

  

 Larry, Oregon

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a58r(at)verizon.net
Guest

Posted: Tue Mar 06, 2007 2:31 pm Post subject: radio noise

Somehow I doubt that running coax Through a ferrite ring/loop will alter the electrical length,  Tell me how this works? 

 regards,

Bob N.    FireFly 070 Old Kolb

http://www.angelfire.com/rpg/ronoy/



do not archive...yet



 



 [quote][b]

jindoguy(at)gmail.com
Guest

Posted: Tue Mar 06, 2007 4:29 pm Post subject: radio noise

Larry, How did you ground the antenna on your radio? If you ground the coax at the radio end and then ground the antenna, too, you can let in all kinds of noise. If you haven't already, try grounding the coax at the radio end only and remove any grounds from the antenna to the airframe. 



Rick



On 3/6/07, Bob Noyer <a58r(at)verizon.net (a58r(at)verizon.net)> wrote:[quote] Somehow I doubt that running coax Through a ferrite ring/loop will alter the electrical length,  Tell me how this works? 

   regards,

Bob N.    FireFly 070 Old Kolb

http://www.angelfire.com/rpg/ronoy/ 

do not archive...yet



 



 [quote][b]  http://www.matronics.com/Navigator?Kolb-List http://forums.matronics.com 

when you live at the airport.  [quote][b]

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Tue Mar 06, 2007 8:24 pm Post subject: radio noise

[quote] ---

a58r(at)verizon.net
Guest

Posted: Tue Mar 06, 2007 8:58 pm Post subject: radio noise

BNC connector is grounded at radio through radio chassis.

 regards,

Bob N.    FireFly 070 Old Kolb

http://www.angelfire.com/rpg/ronoy/



do not archive



 



 [quote][b]

jindoguy(at)gmail.com
Guest

Posted: Tue Mar 06, 2007 9:22 pm Post subject: radio noise

Larry, As Bob said the BNC grounds through the radio chassis. This is all the ground your antenna needs. If you have a second ground from the antenna to the frame you create a ground loop through which all sorts of noise can enter. I found a rat's nest of wire in my mk 3, quite a bit of which was going from the battery, alternator, and various filters to the MicroAir 760 radio. The real problem was that included in the nice big ground plane she had under the antenna mast was a nice fat wire going from said ground plane to ships electrical ground. Once I got rid of that extra ground strap the filters on the alternator and battery (don't ask me, maybe the more is better approach) came off and the noise was quiet. 



Rick



On 3/6/07, Larry Cottrell <lcottrell(at)fmtcblue.com (lcottrell(at)fmtcblue.com)> wrote:[quote]         

 [quote]   ---

R. Hankins

Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon

Posted: Tue Mar 06, 2007 10:06 pm Post subject: Re: radio noise

When tuning my Firestar antenna I reached a point when trimming the antenna length didn't improve the SWR.  The reading was still a 2.7; not horrible, but I wanted better.  I spent an evening or two reading all of the HAM sites about antennas and discovered that one can either match the length of the feed co-ax to the frequency just as one does the antenna, or install a choke or balun to "divorce" the feed line from the antenna. 



I didn't have any ferrite napkin rings around so I trimmed my coax 7" (I got the theoretical magic length from an online antenna calculator a HAM guy put up on his site). I now have an SWR of 1.6.  The co-ax trim made more difference than the antenna trim did.  I'm no radio expert, I just know it worked for me.  I did read enough to get the impression that antenna design is truly a black art.



Here is a link to one of the sites I saved in my favorites.



http://www.electronics-tutorials.com/antennas/antennas.htm



If you want to know about antenna stuff, Ask a HAM!

_________________
Roger in Oregon
1992 KXP 503 - N1782C

by0ung(at)brigham.net
Guest

Posted: Wed Mar 07, 2007 7:32 pm Post subject: radio noise

Somehow I doubt that running coax Through a ferrite ring/loop will alter the

electrical length, Tell me how this works? 



regards,

Bob N. FireFly 070 Old Kolb

http://www.angelfire.com/rpg/ronoy/



chokes and coils are funny animals, especially when hooked up to radios and

antennas.   But in short,,,   by running a coax through a ferrite ring will

in effect create a transformer,   in that some of the energy traveling

through the wire will cause movement of electrons to run around the ring.

This would stop the offending energy from getting to the radio or from the

radio to the antenna...    Depending on the frequency of the interference

and the number of turns around the ring, the size of the ring,  the

offending interference can be eliminated....  but on the other hand some of

the RF signal can also be eliminated.    As to the electrical length....  it

could or will  have an affect on the impedance which could cause you to

change electrical lengths to compensate.  but chokes and coils work

generally in 1 of 2 ways...  they are designed to block a signal,,,  or pass

a signal...  what we would want on an antenna would be a pass filter,

designed to pass all of the radio signals in the range we want to use  and

block all others.   Or if you have interference at a specific frequency,,,

you would want a notch filter to eliminate the offending interference.  And

unless you are more skilled than I,,,,,  the production of these devices is

not best achieved by  a back yard experimenter.



Boyd

by0ung(at)brigham.net
Guest

Posted: Wed Mar 07, 2007 7:32 pm Post subject: radio noise

I am a bit confused as to how you would ground the coax at the radio end.

There is only a BNC connector at the radio end. Sorry, but you are going to

have to be a little more specific for me. :{-)

 

Larry, Oregon

 

do not archive



if you are using a handheld it would be difficult..... but if you have a

panel mount...  it is more than likely grounded through the mounting

hardware.   On the antenna end the grounding would depend on what you are

using for a ground plane.

[Boyd]

a58r(at)verizon.net
Guest

Posted: Wed Mar 07, 2007 9:04 pm Post subject: radio noise

Thanks for the tutorial, Boyd



The current flowing on the inside of the outer conductor, and on the  

outside of the inner conductor in a coaxial transmission line will  

have a difficult time being affected by a ferrite choke; in an open  

wire, yes. BUTT, maybe things have changed of late. Speaking of  

backyards, some 40 years ago I had a 25' dish, with a homemade 1KW  

transmitter on 432.000 mHz aimed at the moon. Had a sked with dentist  

in Zurich E-M-E from Cedar Rapids.



regards,

Bob N.   BSEE '49 Purdue, Ham since 1950

http://www.angelfire.com/rpg/ronoy/



do not archive

R. Hankins

Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon

Posted: Thu Mar 08, 2007 9:57 am Post subject: Re: radio noise

 	  Quote: 	
		  ... the production of these devices is 

not best achieved by a back yard experimenter. 	




One could say the same about building a flying machine... and yet we are all pretty successful at it.  We can get a lot done by learning from people who have taken the time to combine study with experiment and are willing to share their results.  That is the power of this, and other forums.  We are not limited in what we can accomplish to just our own knowlege. 



Ok, I'm off my soapbox now....

_________________
Roger in Oregon
1992 KXP 503 - N1782C

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Thu Mar 08, 2007 7:14 pm Post subject: radio noise

After working on my new hawk house all day I needed a break.  The wind had abated finally for the most part, so I rolled out the Firestar.  This time I put the vinyl enclosure on to see what effect it would have on my  speed and noise. Of course without Jack here it is all speculation.  Over all  I was pleased with the addition.

  

 If you remember in my last post I complained about the noise  from my GPS. This time I wrapped the power cord in the remaining RF Choke.  Unfortunately it made the noise from the GPS worse, so I guess I am going to  have to stock up on batteries. I do not understand where all the noise comes  from, or why a gps puts out static.

  

 With all my "extensive" testing over I resorted to all out  fun. That meant flying no higher than 50 feet off the sage, and flying contour.  I thought for a little bit about what I would do if the engine quit, but decided  to ignore it and just have fun. I was looking for Coyotes or any other living  thing. I checked out a new property that had just been sold, and then decided to  be a bit more conservative and fly up the hwy. Still at telephone pole high I  had a race with a semi who lost. At WOT I was doing 82 on the ground, and 72 at  6000 rpms. I flew for about 20 minutes buzzing a Golden Eagle sitting on a Sage  bush, and flying up the creek making knife edge turns, (at least that is what I  felt) until it begin to get dark  enough to make landing a  necessity. I do feel better! I like my little hot rod!

  

 Larry, Oregon 

    [quote][b]

Russ Kinne

Joined: 27 Jan 2006
Posts: 182

Posted: Mon Mar 12, 2007 5:20 pm Post subject: radio noise

Bob N/aging expert

Can you tell me brand name of flashlite that charges a cellphone?  

Would appreciate.

Also, thee & mee are way too young (!!) to remember the shenanigans  

that went on in WWII, but a chap I worked with did work for Federal  

Electric in NJ during  the end of the war -- he were a most talented  

& active Ham, built a xmtr and axed the FAA for permission to test  

it. OK with a dummy load, they said.

So he put his dummy load at the end of about 100yd of bright shiny  

new copper wire & had at it., They say he swept the whole 10-meter  

band? is that correct? Anyway he never got more than yelled at  

(considerably)  -- I liked him a lot, and his attitude got lots of  

difficult projects done later on -- which we both were grateful for --

Best,

Russ



On Mar 8, 2007, at 12:04 AM, Bob Noyer wrote:



 	  Quote: 	
		   



 Thanks for the tutorial, Boyd



 The current flowing on the inside of the outer conductor, and on  

 the outside of the inner conductor in a coaxial transmission line  

 will have a difficult time being affected by a ferrite choke; in an  

 open wire, yes. BUTT, maybe things have changed of late. Speaking  

 of backyards, some 40 years ago I had a 25' dish, with a homemade  

 1KW transmitter on 432.000 mHz aimed at the moon. Had a sked with  

 dentist in Zurich E-M-E from Cedar Rapids.



 regards,

 Bob N.   BSEE '49 Purdue, Ham since 1950

 http://www.angelfire.com/rpg/ronoy/



 do not archive

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Thu Mar 15, 2007 11:46 am Post subject: radio noise

Subject: Re: radio noise

[quote]

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