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Radio/Comm issue! Grounding airplane from flying... HELP!

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airplayn

Joined: 23 Aug 2012
Posts: 8

Posted: Sun Nov 04, 2012 5:45 pm Post subject: Radio/Comm issue! Grounding airplane from flying... HELP!

Make sure that EVERY different piece of electronics has it's own single and  INDEPENDENT ground wire. shared ground wires can lead to bad crosstalk and problems like you are having. That should help significantly.



Timothy A. Kiehl    



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		   Subject: Zenith601-List: Radio/Comm issue! Grounding airplane from flying... HELP!

 From: Chad2007(at)rogers.com

 Date: Sun, 4 Nov 2012 16:06:33 -0800

 To: zenith601-list(at)matronics.com

 

 --> Zenith601-List message posted by: "SIDESLIP" <Chad2007(at)rogers.com>

 

 Hello all. Just purchased a Homebuilt Zodiac 601XL-B. Rotax 912ULS powered. A200 Radio, Flightcom 403 intercom. Aero flash strobes. The radio is intermittently squealing and tower cannot understand my transmissions. Tried both engine running and not running. Intermittent either way. When it is working, I get 5/5. When it begins squealing, 0/0. Previous owner said he had the same issue with cheaper headsets. Radio worked great, then it didn't. I'm using David Clark 13.2s's. The previous owner has a portable wired in as well, telling me that he's had issues in the past. There is a falcon T/B gyro, Garmin transponder and aero flash strobes. When the strobes are on, the pop of the flash comes thru headsets. I'm really stuck! Bought this plane, and now can't fly it! The rest of the plane is great,, ending runs PERFECT..... But this radio issue has me beat! HELLLP!

 

 Chad

 

 --------

 C-GYXQ. 912ULS. 601XL-B

 

 

 

 

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_________________
Tim Kiehl
airplayn@hotmail.com

Zodiac HDS601
1940 Taylorcraft BC-65
1951 Bellanca Cruisemaster 14/19
Glendale Airport (GEU)
Glendale AZ

tigerized(at)gmail.com
Guest

Posted: Tue Nov 06, 2012 8:37 am Post subject: Radio/Comm issue! Grounding airplane from flying... HELP!

Forgive me if you've already answered this, but could this be as simple as acoustic feedback?



If your comm radio's sidetone is cranked all the way up, and it's feeding back into your boom mic, you'll get a squeal that will obliterate all voice.

 

Rick



On Tue, Nov 6, 2012 at 8:14 AM, SIDESLIP <Chad2007(at)rogers.com (Chad2007(at)rogers.com)> wrote:

[quote] --> Zenith601-List message posted by: "SIDESLIP" <Chad2007(at)rogers.com (Chad2007(at)rogers.com)>

 

 Bob;

 

 I don't believe that there is a menu selection in the A200 for gain. An AME pulled the radio today and is sending it for bench testing. Hopefully this is something simple! Getting really frustrated! Spent all this money on this airplane, and now can't fly it! Sucks!!!

  

 Stay tuned....

 

 Thanks Bob!

 

 

 Chad

 

 --------

 C-GYXQ. 912ULS. 601XL-B

 

 

 

 

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 http://forums.matronics.com/viewtopic.php?p=387087#387087

 

 

 

 

 

 

 

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Posted: Tue Nov 06, 2012 8:48 am Post subject: Radio/Comm issue! Grounding airplane from flying... HELP!

Chad,



I'm glad to hear you are having the radio bench tested.  I was thinking 

of suggesting something like that.



My thought was that having two transmitters connected to the same 

antenna might cause one or the other to be damaged.  I'm not sure it 

even matters if one is turned off while the other is transmitting. The 

power of the transmitter might damage the other radio even if it is 

turned off.



Good luck,



Paul

Camas, WA



On 11/6/2012 8:14 AM, SIDESLIP wrote:

 	  Quote: 	
		   



 Bob;



 I don't believe that there is a menu selection in the A200 for gain. An AME pulled the radio today and is sending it for bench testing. Hopefully this is something simple! Getting really frustrated! Spent all this money on this airplane, and now can't fly it! Sucks!!!



 Stay tuned....



 Thanks Bob!

 Chad



 --------

 C-GYXQ. 912ULS. 601XL-B





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=387087#387087

SIDESLIP

Joined: 14 Oct 2012
Posts: 78
Location: CYOO

Posted: Tue Nov 06, 2012 10:02 am Post subject: Re: Radio/Comm issue! Grounding airplane from flying... HEL

Hey guys....



Could it be feedback? If it were, would the tower not be able to hear me either? That theory makes sense to me... Ive messed around with High Power CB radios and SSB stuff in years past. Ran a 500Watt boot on the CB radio in my car. Had a TON of trouble shooting to do with that much power. Ran dual alternators and batteries. I never encountered feedback though..... but turned anything within 500 feet with metal in it into a speaker though! I think i actually have a SWR meter still around somewhere. Both radios have their own independent antennas, so there isnt a mixing between the two. Like I said before.... Im praying the radio has issues.... HA! That would make it an easy fix.



The previous owner said he never had any issues until recently..... IF that is true, then the wiring should be correct and proper. He says that hes ALWAYS heard the strobe 'PoP' from day one however..... so there still must be an RF leak somewhere still. Hopefully the bench test shows something. Truthfully...... Id rather spend $1300.00 on a new A210 that plugs straight in and be done with it if it were that simple. Wiring scares me! Such a pandora's box of possibilities.....



It does sound like feedback though.... Honestly. But, like I said, if it were in fact a feedback issue between the comm and the Flightcom 403mc, would tower still not get a clear voice? The other thing.... the radio slid out of the tray really easy, so I wonder if some of the connections in the tray were intermittent?



Thanks guys!



Chad

_________________
C-GYXQ. 912ULS. 601XL-B

psm(at)att.net
Guest

Posted: Tue Nov 06, 2012 10:20 am Post subject: Radio/Comm issue! Grounding airplane from flying... HELP!

Hi Chad,



I am not optimistic on the feedback theory.  If you are using a 

headphone with directional microphone (the aviation norm) it would be 

hard to get sound from the ear pieces to the mike.  That would be audio 

sidetone back to the mike type feedback.  If the transmit signal is 

somehow getting into the receiver then the radio is broken.  The 

receiver should be turned off when the transmitter is hot.



Paul



On 11/6/2012 10:02 AM, SIDESLIP wrote:

 	  Quote: 	
		   



 Hey guys....



 Could it be feedback? If it were, would the tower not be able to hear me either? That theory makes sense to me... Ive messed around with High Power CB radios and SSB stuff in years past. Ran a 500Watt boot on the CB radio in my car. Had a TON of trouble shooting to do with that much power. Ran dual alternators and batteries. I never encountered feedback though..... but turned anything within 500 feet with metal in it into a speaker though! I think i actually have a SWR meter still around somewhere. Both radios have their own independent antennas, so there isnt a mixing between the two. Like I said before.... Im praying the radio has issues.... HA! That would make it an easy fix.



 The previous owner said he never had any issues until recently..... IF that is true, then the wiring should be correct and proper. He says that hes ALWAYS heard the strobe 'PoP' from day one however..... so there still must be an RF leak somewhere still. Hopefully the bench test shows something. Truthfully...... Id rather spend $1300.00 on a new A210 that plugs straight in and be done with it if it were that simple. Wiring scares me! Such a pandora's box of possibilities.....



 It does sound like feedback though.... Honestly. But, like I said, if it were in fact a feedback issue between the comm and the Flightcom 403mc, would tower still not get a clear voice? The other thing.... the radio slid out of the tray really easy, so I wonder if some of the connections in the tray were intermittent?



 Thanks guys!



 Chad



 --------

 C-GYXQ. 912ULS. 601XL-B





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=387098#387098

airplayn

Joined: 23 Aug 2012
Posts: 8

Posted: Tue Nov 06, 2012 1:06 pm Post subject: Re: Radio/Comm issue! Grounding airplane from flying... HEL

I reiterate, have you checked ALL grounds to ALL electronic equipment and made sure NONE of them SHARE A GROUND? Check all grounds (and not just communication equipment, even meters or indicators, anything that has a ground wire) for looseness or bad connection and do not share any ground wire between devices. It doesn't sound like it would make a difference, but it does! Sharing grounds may cause feedback circuits to develop even if the radio is not on the same ground. Sometimes one of the multiple grounds may be a slight high resistance and it two systems are on that ground can cause problems on every other system, even if it does not share that ground.



I really do have experience in this problem and this is one of the first things any good radio shop will tell you to check. I've been building and restoring aircraft since the 70's and also used to be an electronic tech.



Tim

SIDESLIP

Joined: 14 Oct 2012
Posts: 78
Location: CYOO

Posted: Tue Nov 06, 2012 1:23 pm Post subject: Re: Radio/Comm issue! Grounding airplane from flying... HEL

Tim;



I know what you are saying, and I've also had actual personal issues with bad grounds before. Electricity will find the least resistant method of completing a circuit. I've seen it first hand. I haven't had a chance to climb under the dash, as you need to be a contortionist to do so, and it's freezing here. Where my confusion comes in is that almost all of the research I've done says to actually group the grounds together. Avionics together, NAV lights together and so on. So, which do I do? Grounds to same spot / block or to all different places on the airframe? Flightcom says to make the grounds all terminate together. So, you can imagine my confusion. I think a few of the grounds were made by riveting the grounds to the airframe in a few locations. The other challenge is to actually LOCATE all the grounds. 



Thanks for your help Tim! It is VERY appreciated!



Chad

_________________
C-GYXQ. 912ULS. 601XL-B

airplayn

Joined: 23 Aug 2012
Posts: 8

Posted: Tue Nov 06, 2012 1:38 pm Post subject: Re: Radio/Comm issue! Grounding airplane from flying... HEL

The individual ground wires can go to the same ground connection ON THE FUSELAGE, but they all have to be parallel and have their own wire.



check out these websites which have info on grounding problems and fixes (you don't have to read the whole thing if you don't want to, just scan for the ground sections):



http://www.radioworks.com/nbgnd.html



http://www.sacskyranch.com/bond.htm



http://www.zenithair.com/kit-data/ra/electric2.html



and a here are downloadable PDF file with full aircraft wiring tips AND sections on "that evil ground".



www.eaa.org/experimenter/articles/0903_aircraft_wiring.pdf



engineer.jpl.nasa.gov/practices/1214.pdf



 Remember, ground loops are not only in taildraggers! LOL

airplayn

Joined: 23 Aug 2012
Posts: 8

Posted: Fri Nov 09, 2012 10:28 pm Post subject: Radio/Comm issue! Grounding airplane from flying... HELP!

If your com bench checked then this IS more than likely a ground issue. I used to be a TV repairman and the terrible truth in these "dogs" is that you just have to bit the bullet and start replacing the grounds. For example, I'd spend ten hours on a dog knowing I could never charge for ten hours labor, you just remembered all the ten minute fixes you charged an hour for. Did I hate to do that? well, it was that or scrap the set. You can't scrap the plane, but this "component" is an integral part. I bet that if you really start replacing those grounds you're gonna "discover" a bad one.  The same thing sometimes happened on those "dogs", one of the components I suspected and "looked" and "tested" good would FALL APART in my hands when I pulled it!Good Luck and keep a stiff upper lip!



Timothy A. Kiehl    



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 	  Quote: 	
		   Subject: Re: Radio/Comm issue! Grounding airplane from flying... HELP!

 From: Chad2007(at)rogers.com

 Date: Fri, 9 Nov 2012 19:20:20 -0800

 To: zenith601-list(at)matronics.com

 

 --> Zenith601-List message posted by: "SIDESLIP" <Chad2007(at)rogers.com>

 

 Anyone???

 

 Chad

 

 Bob? He's the expert?

 

 --------

 C-GYXQ. 912ULS. 601XL-B

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=387415#387415

 

 

 

 

 

=====================
	


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  [quote][b]

_________________
Tim Kiehl
airplayn@hotmail.com

Zodiac HDS601
1940 Taylorcraft BC-65
1951 Bellanca Cruisemaster 14/19
Glendale Airport (GEU)
Glendale AZ

SIDESLIP

Joined: 14 Oct 2012
Posts: 78
Location: CYOO

Posted: Sun Nov 11, 2012 8:20 pm Post subject: Re: Radio/Comm issue! Grounding airplane from flying... HEL

****** UPDATE!!!!



I fingered around to check for loose grounds etc..... But....



So, fellas,



I figured I'd start a new thread about this, since I have narrowed the issue down.



So, the A200 was bench tested, and tested out fine. The only item that seemed out of whack, was the side tone, which was set VERY high. I cleaned the terminals on the back of the radio prior to install. I tightened the radio into its tray firmly, and proceeded to test. The squeal seemed to be gone on 129.10, both with engine running, and without. This problem I BELIEVE is definitely a squelch problem. I transmitted the squeal, and while mid transmit, unplugged the mic cord. The squeal stopped immediately. Then I tried messing with different volume/squelch settings on the flightcom. To no avail, squeal still present....



Here is where it gets weird.... I pulled the mic away from my face, NO MORE SQUEAL! Well, very very little, and when I tapped the mic, it tried to come back, but then faded. So, I figured, let's try the tower. I turned my head looking over my right shoulder, and ZERO squeal. When I am facing straight ahead, and get it to squeal, while it is mid squeal, I cover the mic with my hand, and it deadens it considerably! 



IF this was wiring, here is how I disprove that theory....



The handheld transmits and receives PERFECTLY and gives 5/5 no matter what! Worked seamless. Flip back to the A200, and squeal! Keep in mind, the handheld is wired into the flightcom as well, and shares all of the same wiring as the A200! So, the final question........ Could this be as simple as the mic gain on the 200? With the engine running, there is zero interference from the engine. On BOTH radios. I think that this proves that the grounds are good, wiring is good and the flightcom is good. I still get the strobe POP when they fire, but I get that SAME pop in the Cessna 172M I fly! So, that is an acceptable noise for me. And since a certified very high dollar factory built airplane has strobe noise, I'm not too concerned about this one. It really is quiet. So...... MIC GAIN, OR NOT TO MIC GAIN ADJUST? Or try changing antennas? Thoughts? After changing the side tone, it is MUCH better. Still not acceptable, but it DID get better. I've read a lot of people suggesting to adjust the mic gains, with great results for them, yet others say it won't do a thing. It is DEFINITELY feedback like you'd hear from an amplifier too close to an electric guitar. 



I feel that I'm right on the edge of solving this problem.....I'm thinking, that if I can change antennas and that resolves it, it may be as simple as a faulty antenna, or maybe even not the right one?



It's would be great to hear some feedback from the pro Bob Nuckolls.

Thanks in advance!!! I appreciate ALL of your inputs! Dying to try to solve this so I can go flying my new airplane!

Chad Scriver

_________________
C-GYXQ. 912ULS. 601XL-B

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