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rparigor(at)SUFFOLK.LIB.N
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Posted: Wed Feb 18, 2009 9:53 pm Post subject: Help needed obtaining filter

Any ideas on how to filter out 100 milivolt spike that is very very sharp with a duration of ~ 75 miliseconds coming from Kuntzleman strobe power supply, then radiating off power lines and getting into my antenna? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Getting closer to resolve to my tick, tick, ticking coming from Kuntzleman strobe. First off It is the Vertex VXA-700 that is currently breaking squelch. I called factory today and they said when you put an aircraft antenna on them, they are sensitive and there is nothing they know of they can do to help me out.. Next is high voltage from power supply, believe it or not, using the shielded cable from Kuntzleman, doesn't matter much if you have 1 foot or 25 feet, it just doesn't radiate that much. The Kuntzleman power supply radiates a lot no matter how you ground things, but 8 feet away with antenna under worst case and 6 feet away under best case eliminates tick, tick, ticking. So power supplies will live in wingtips away from antennas. The power wires are the culprit at the moment! First off I am running Vertex on internal battery so it is not dirty radio supply power causing the problem, it is RF jumping off the supply lines getting into antenna! Using shielded wire for supply has more RF jumping off compared to twisted pair no matter how I grounded shield! Can't explain it but it is so. Twisted pair is slightly better than untwisted pair, running a separate ground wire to case of power supply makes no difference compared to grounding box to black supply wire. Using twisted pair with optimum grounding, now has ticking only happening on lower and higher frequencies. Observing supply power at battery on a scope, there are very very sharp spikes 100 milivolts, with a duration of about 75 miliseconds that equate perfectly to Vertex VXA-700 breaking squelch. Anyone have any ideas on how I can filter this out? And where to get parts needed? I guess I will need two filters, one for each power supply at the wingtips. I ripped a choke bout an inch in diameter off a junk copier laying around hangar and tried it in series with positive at power supply, and also tried wrapping both twisted pair through it 3 times (all that would fit) with no change at all.I see Aircraft Spruce sells a DC line filter:http://www.aircraftspruce.com/catalog/elpages/lsStrobeNoiseEl.phpMore expensive (need 2) and heavier that I would likeRon P.   [quote][b]

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nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 19, 2009 8:55 am Post subject: Help needed obtaining filter

At 11:48 PM 2/18/2009, you wrote:

  	  Quote: 	
		  Any ideas on how to filter out 100 milivolt spike that is very very sharp with a duration of ~ 75 miliseconds coming from Kuntzleman strobe power supply, then radiating off power lines and getting into my antenna? 



 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

 Getting closer to resolve to my tick, tick, ticking coming from Kuntzleman strobe. First off It is the Vertex VXA-700 that is currently breaking squelch. I called factory today and they said when you put an aircraft antenna on them, they are sensitive and there is nothing they know of they can do to help me out.. 



 Next is high voltage from power supply, believe it or not, using the shielded cable from Kuntzleman, doesn't matter much if you have 1 foot or 25 feet, it just doesn't radiate that much. 



 The Kuntzleman power supply radiates a lot no matter how you ground things, but 8 feet away with antenna under worst case and 6 feet away under best case eliminates tick, tick, ticking. So power supplies will live in wingtips away from antennas. 



 The power wires are the culprit at the moment! First off I am running Vertex on internal battery so it is not dirty radio supply power causing the problem, it is RF jumping off the supply lines getting into antenna! 	


    I just checked over the Kuntzleman website . . . remarkably

    lacking in 



 

  	  Quote: 	
		  Using shielded wire for supply has more RF jumping off compared to twisted pair no matter how I grounded shield! Can't explain it but it is so. Twisted pair is slightly better than untwisted pair, running a separate ground wire to case of power supply makes no difference compared to grounding box to black supply wire. 



 Using twisted pair with optimum grounding, now has ticking only happening on lower and higher frequencies. 	


    Shielding and twisting has limited if any value in

    mitigation of radiated emissions. Frankly, this

    is something that needs to go back to the manufacturer.

    The website speaks to noise with these words:



 "Our strobe driver units are designed with filtering and internal shielding to keep radio interference to a minimum, however occasionally noise will be heard over the radio or intercom. This noise is almost always caused by the way the systems have been installed."



    That's our first clue. I'd have a hard time selling

    any product to the TC aviation where variability of

    installation causes a system integration issue.



    On the same website we find:



 "AFTER CHECKING items 2, 6, & 7 a small AM radio can be used as follows. Turn on and tune between two stations. Hold the radio near the strobe driver box. A clicking of the strobe trigger circuit should be heard. If not, then trouble is in the driver box and it should be returned to Kuntzleman Electronics for repair. If it is heard move the radio to near the strobe head, that same clicking will be heard and the problem is the bulb unit. New bulb units are available from Kuntzleman Electronics."



    The two statements are somewhat at odds with each other

    and perhaps an indication of the source of your problem.

    I'm betting that better filtering of the DC

    power leads while STILL INSIDE the driver box

    is called for.



    How much current does this system draw? I didn't

    find any info on their website.



 

  	  Quote: 	
		  Observing supply power at battery on a scope, there are very very sharp spikes 100 milivolts, with a duration of about 75 miliseconds that equate perfectly to Vertex VXA-700 breaking squelch. 



 Anyone have any ideas on how I can filter this out? And where to get parts needed? 



 I guess I will need two filters, one for each power supply at the wingtips. 	


     ??? Which system do you have?  My sense of your

     description is that you've found a centrally locate

     power supply to be the source of noise . . . this

     is consistent with the Kunzleman description of

     using an AM radio to see if the power supply

     is functional.



 

  	  Quote: 	
		  I ripped a choke bout an inch in diameter off a junk copier laying around hangar and tried it in series with positive at power supply, and also tried wrapping both twisted pair through it 3 times (all that would fit) with no change at all.



 I see Aircraft Spruce sells a DC line filter: 	


     Chokes are ALWAYS used in conjunction with

     capacitors. See chapter 16 in the 'Connection.

     I have an off the shelf filter you can try.



  http://www.aeroelectric.com/Catalog/AEC/9006/



     It's good for 3A continuous which MAY be adequate

     to your task. 



     Bob . . .

     [quote][b]

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