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  #1  
Old 03-03-2021, 07:29 AM
bob888 bob888 is offline
 
Join Date: Jul 2012
Location: Fresno, CA
Posts: 293
Default Alternator static

I am having intermittent static in the radios that goes away when I switch off the alternator (Plane Power internally regulated). This is not the 'whine' typical of a bad diode but a harsh static loud enough to compromise radio communication. The question is...are these alternators repairable or need to just replace?
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  #2  
Old 03-03-2021, 09:11 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,856
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I don't have one, but reading here tells me they leave a lot to be desired. I would start by getting your VOM out and confirming that the engine to airframe and engine to alternator grounds are good (< .1 ohms). I have also seen numerous post stating that the 3 pin connector on the PP goes bad and creates an intermittent connection.

Larry
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  #3  
Old 03-03-2021, 10:09 AM
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Raymo Raymo is offline
 
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,295
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It can be repaired. Mine went out with around 300 hours. Replaced with new under warranty but I opted to go with a B&C instead and sold the new one they sent me.
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RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)
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  #4  
Old 03-03-2021, 11:57 AM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 532
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Quote:
Originally Posted by bob888 View Post
I am having intermittent static in the radios that goes away when I switch off the alternator (Plane Power internally regulated). This is not the 'whine' typical of a bad diode but a harsh static loud enough to compromise radio communication. The question is...are these alternators repairable or need to just replace?
Static is a funny thing - before you throw the PP alternator into the trash, have a look at the isolation washers under the Mic & Phone jacks...maybe even replace them.

Here's my story - RV-7 started developing intermittent static after a few years in service. This static could be heard on top of received radio transmissions, flying VMC and transitioning in IMC would make it worse/followed turning on the PITOT HEAT; the noise would break the squelch limit on one of the radios.

The root cause, was slight cracking in the isolation washers at the microphone jack on co-pilot side. Some sort of ground-loop developed and the co-pilot mic was fuzzing into the audio system...

Good Luck!
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Brian Decker
Retired Firmware Guy and Airplane Builder

2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
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