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Troubleshooting radio whine/noise on Cessna 182P

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ngeorge(at)continentalmot
Guest

Posted: Tue Nov 24, 2015 7:55 am Post subject: Troubleshooting radio whine/noise on Cessna 182P

Sasha - 

The PlanePower voltage regulators are adjustable, and must be adjusted at installation.

It would probably be a good idea to replace the Split Master switch, too.



neal



--

jan(at)CLAVER.DEMON.CO.UK
Guest

Posted: Tue Nov 24, 2015 8:07 am Post subject: Troubleshooting radio whine/noise on Cessna 182P

Well, depending on the technology used for the voltage regulation - the noise can be generated by the regulator.



The noise  filter that you currently have fitted would have been tuned to the old regulator - new regulator could very well need a new filter, tuned for the current regulator.

If the noise pitch is changing with rpm - that would sound to me as if the noise is from the regulator as it does its work regulating the output voltage 



All the best



Jan



[quote] On Nov 24, 2015, at 15:53, Neal George <ngeorge(at)continentalmotors.aero> wrote:

 

 

 

 Sasha - 

 The PlanePower voltage regulators are adjustable, and must be adjusted at installation.

 It would probably be a good idea to replace the Split Master switch, too.

 

 neal

 

 --

sacha

Joined: 04 Jan 2015
Posts: 15

Posted: Tue Nov 24, 2015 8:37 am Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

Thank you for your inputs. 

I'm sorry it's a little difficult for me to know exactly what is going on as I am receiving reports from the A&P, not working on the plane directly (as I a not allowed to). 

I just got another email from the A&P saying that after multiple calls to Plane Power they think they have it correctly installed, but there is some concern that the bus voltage is very slow to come up.  Could this be due in any way to a defect of the over voltage protection?



Hmmmm....  maybe the most expeditious solution would be to install a Ford regulator and a new master switch.

sacha

Joined: 04 Jan 2015
Posts: 15

Posted: Tue Nov 24, 2015 8:55 am Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

Ok things are even more complicated as I just noticed that the plane power regulator has internal over voltage protection and so the over voltage protection on the a/c must now be bypassed. 



I get the feeling that I'm gonna have to carefully read the instructions and make sure that they are being followed by the shop!

paulmillner

Joined: 09 May 2007
Posts: 21
Location: Berkeley, California

Posted: Tue Nov 24, 2015 10:09 am Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

 	  sacha wrote: 	
		  Ok things are even more complicated as I just noticed that the plane power regulator has internal over voltage protection and so the over voltage protection on the a/c must now be bypassed. 



I get the feeling that I'm gonna have to carefully read the instructions and make sure that they are being followed by the shop! 	




Hi Sacha,



Why can't you work on your own airplane, under A&P supervision? Who does not "allow" you to?



You have to verify that the old OV relay was removed... it could be defective and causing your regulation problem.



You do NOT want a Ford automotive regulator... it can cause an overvoltage situation that even an external OV relay cannot overcome (the automotive regulator sources regulator power directly from the alternator, and thus ignores whether the OV relay or alternator half of the master switch are providing power, or not.)



Paul

_________________
Paul Millner, Berkeley CA [OAK]

sacha

Joined: 04 Jan 2015
Posts: 15

Posted: Tue Nov 24, 2015 10:39 am Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

You're right Paul - that's a good idea. Problem is I Guest I would have to take time off work during weekdays (when the A&P is around) but I can't right now. 



The old OV system has been removed and the bus voltage is now 14.2V.  



So now we just have to figure out where the noise is entering the system.

ceengland7(at)gmail.com
Guest

Posted: Tue Nov 24, 2015 11:18 am Post subject: Troubleshooting radio whine/noise on Cessna 182P

On 11/24/2015 12:39 PM, sacha wrote:

 	  Quote: 	

 You're right Paul - that's a good idea. Problem is I Guest I would have to take time off work during weekdays (when the A&P is around) but I can't right now.

 The old OV system has been removed and the bus voltage is now 14.2V.

 So now we just have to figure out where the noise is entering the system.

'Under supervision' doesn't mean that he has to stand there looking over 

your shoulder. As long as he's willing to sign on the dotted line at the 

end of the process, you could rebuild the entire a/c while he's 

vacationing in Tahiti.

 From a previous post:

 >>

You do NOT want a Ford automotive regulator... it can cause an overvoltage situation that even an external OV relay cannot overcome (the automotive regulator sources regulator power directly from the alternator, and thus ignores whether the OV relay or alternator half of the master switch are providing power, or not.)

 	  Quote: 	
		  >

I can't make sense of this, as long as we're talking about an externally 

regulated alternator. Ford style regulators are flying in thousands of 

homebuilts safely (assuming that OV protection is used). As long as the 

wire to the field is interrupted, the alternator cannot produce power. 

Typical OV protection circuits either open the field lead or 'crowbar' 

it to ground, tripping the field circuit breaker (which breaks the field 

circuit). Either way, there's no way for the regulator to keep the 

alternator operating.

For noise: What's the ground path from the alternator frame to the 

battery, and from the regulator negative to the battery? (Make sure 

neither uses the motor mount as part of the circuit.) What's the ground 

path back to the battery of the radio where you're hearing the noise?

If the noise is happening in receive mode on the radio, try 

disconnecting the antenna coax from the radio (don't transmit while it's 

disconnected). If the noise stays the same, the noise is probably 

entering through the B+ lead or the ground. If the noise goes away, it's 

probably being radiated from the alternator and/or the regulator into 

the antenna or coax. Check the coax ground for continuity and check the 

antenna mount for proper grounding.

Charlie

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Tue Nov 24, 2015 2:57 pm Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

For testing purposes, temporarily connect a 12 AWG jumper wire from the alternator "B" terminal to the avionics bus and listen to see if the whine goes away.  If that is not doable, measure the voltage between the alternator "B" terminal and the avionics bus while the engine is running and all electrical loads are turned on.  I would expect that voltage drop to be only millivolts.

 Is measuring voltage considered "working" on an airplane?

_________________
Joe Gores

sacha

Joined: 04 Jan 2015
Posts: 15

Posted: Tue Nov 24, 2015 4:24 pm Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

Charles/Joe,

thanks.  I will do the antenna coax test, and, assuming it's not entering via the antenna, I'll do the test that Joe recommended by connecting the B-lead and the avionics bus.  

On the ground side of things, the alternator is tied to the engine crankcase which is tied to the airframe.  The battery is rear mounted and locally grounded to the airframe.  I think the best i can do there is to check each connection to make sure it's in tip-top condition and appropriately greased to prevent corrosion.

I'll also check the capacitors that mounted on the B-lead so see if they are still operational.

Sacha

sacha

Joined: 04 Jan 2015
Posts: 15

Posted: Tue Nov 24, 2015 4:34 pm Post subject: Re: Troubleshooting radio whine/noise on Cessna 182P

Neal, 

thank you for that.  I only just saw your post.  It looks like the issue with the regulator has been sorted out.  I'm guessing the master switch is fine too but I'll bypass it in a test just to be sure.

Sacha

ceengland7(at)gmail.com
Guest

Posted: Tue Nov 24, 2015 7:53 pm Post subject: Troubleshooting radio whine/noise on Cessna 182P

Uh...I stand corrected. Shame Cessna       can't be.

       

       On 11/24/2015 7:13 PM, Paul Millner wrote:

     

      	  Quote: 	
		                Charlie,

       

       The problem is that you're not aware of how Cessna wired the       regulator in this 182...

       

       Instead of the OV relay interrupting the current path between the       regulator and the field terminal as you propose OBAM folks usually       do it, the OV relay and the alternator half of the master switch       interrupt the power supply *to* the regulator, via the S or Supply       terminal.

       

       However... the automotive version supplies the regulator and       alternator from both the S and the A terminal... and once the       master is on, the A terminal is hot... so the Cessna OV relay and       alternator half of the master switch are irrelevant.

       

       So... an automotive regulator in the Cessna wiring diagram? The       alternator is non-controllable... which could be a bad thing.

       

       See attached wiring diagram.

       

       Paul

       

       http://www.secure4host.net/upload/files/Cessna_Alternator_Wiring.pdf

       

       On 11/24/2015 11:18 AM, Charlie         England wrote:

       

        	  Quote: 	
		  You         do NOT want a Ford automotive regulator... it can cause an         overvoltage situation that even an external OV relay cannot         overcome (the automotive regulator sources regulator power         directly from the alternator, and thus ignores whether the OV         relay or alternator half of the master switch are providing         power, or not.) 

         

          	  Quote: 	
		              	  Quote: 	
		   

           	
         	
         

         I can't make sense of this, as long as we're talking about an         externally regulated alternator. Ford style regulators are         flying in thousands of homebuilts safely (assuming that OV         protection is used). As long as the wire to the field is         interrupted, the alternator cannot produce power. Typical OV         protection circuits either open the field lead or 'crowbar' it         to ground, tripping the field circuit breaker (which breaks the         field circuit). Either way, there's no way for the regulator to         keep the alternator operating.

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