Intermittent 430W com static

Jim Boyd

Filing Flight Plan
Joined
Mar 6, 2018
Messages
11
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KOJC KLXT
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JB
Back in 2012 I was having issues with com static on a 430W. After installing an alternator noise filter, replacing the ELT and adjusting the squelch on the 430 everything was great. Now, on the last 2 takeoffs the static is back BUT... it only lasts up to around 2,000 AGL then falls off. Climbing to 8,500 then is quiet, cruise is quiet. No power adjustments in the climb and minimal static, if any, in the descent except around 2,000 AGL then all quiet down to the pattern and landing. So it's mostly a full power thing but only up to around 2,000 AGL...hmmm...??? First guess is the noise filter is going bad? Any other thoughts?
 
Thoughts:

Local interference on the ground or in the area. Is it on all frequencies?

Something heating up and making better contact in your electrical system as it heats and expands under the coal.
 
Well, all good questions. I haven't ventured to other airports so far but it is on all frequencies or at least 2-3 that I have flipped in to so far. The static intermittently starts at around 40-45 knots on the takeoff roll and becomes constant after takeoff. Remains constant until around 2,000 agl and then becomes intermittent and then clears by 2,500-3,000 agl. I make no change in power, pitch, etc... Lycoming O-360. My other radio is a King KX-165 and it remains static free...
 
Wild, fact free guess - is there an ILS?
 
You might look into emergency or hospital services in the immediate area. I know of a particular area where the emergency comms center at a hospital causes interference to all radios in the vicinity...
 
Do you have any portable electronics turned on? I had a portable ADS-B receiver that would cause static on both the 430W and the SL40.
 
The emergency/hospital post is interesting. There is a hospital just south of the airport so I'm wondering if they've put in new radios that's giving the Garmin fits. It's always been more sensitive - the KX165 has never given me any fits. No portable electronics on other than my cell phone but that's always been on and haven't had the issue until the last 2 flights 7 days apart. Thanks!
 
Does your alternator have a field switch ? If so, try turning it off when you hear the static to see if it could be an alternator or voltage regulator issue. Your battery will charge at a higher rate after takeoff .

Yeah this is the next thing I would try with it being on all frequencies. It’s more likely to be on board the aircraft with that piece of news.
 
Thanks to all for your replies. One other simple option I want to check based on other posts is the USB charger in the cigarette lighter. If I leave it out and it clears then easy fix. Otherwise I'll run the alternator field test- thanks!
 
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