lml@lancaironline.net Mailing List Archive

I had similar problems with my ES comm. In my case I found two causes. The first was the aux audio input jack for my comm panel. It was mounted on the aluminum dash, which created a ground loop as the barrel of the connector was then connected by both a wire and the panel. Disconnecting the jack eliminated the hum. Note that the hum was there even when the aux jack was not enabled – just its presence created a ground loop.

The second issue was noise emanating from my LED position lights. This noise only affected the lower comm frequencies, while the aux jack loop created a buzz all of the time. You can source these kinds of problems by opening the fuses one by one until the problem goes away.

Pete

From: YahooMail [mailto:arrow54t@yahoo.com]
Sent: Thursday, October 24, 2013 6:06 AM
To: lml@lancaironline.net
Subject: Re: [LML] Noisy COM on low end freqs only....?

Gordon,

I had very similar experience with my ES. I tried the alternator filter capacitor idea with no luck too. I could eliminate the noise by turning off the alternator field. Turned out to be a ground loop due to the aluminum headphone mounting jack plates for the rear seat passengers. I installed plastic washers with a flange so that the jack bodies wouldn't touch the metal plate. Aircraft Spruce sells them just for this purpose. Originally I had plastic washers that didn't have the flange that keeps the jacks in the center of the hole. No more whining in my plane except from some passengers when there is turbulence!

Hope this helps,

Mike Salzman

2005 LNCE

Fairfield, CA

Sent from my iPad

On Oct 21, 2013, at 7:37, "Gordon Porter" <ghp@trustedwealthadvisors.com> wrote:

Well, I have been flying my Lancair ES for 90 hours and loving it. Knocking off the last of the minor squawks. One that has me perplexed is a very staticy COM background noise:

Get it on both radios - a G530 and an SL30, on different antennae

SL 30 is on an exterior Comant 121; G530 is on a bonded in AAE in vertical

My transmissions are heard fine

I actually here incoming transmissions when it is staticy fairly well, most of the time

The WEIRD part is it is 100% reproducible on 118.xx, 119.xx and 120.xx freqs only. Rest of freq spectrum is crystal clear with good range

I thought I had it narrowed down to the Primary ALT since at 8-900 RPM I could switch the static off and on with the field switch. So, I put one of those big capacitors (from B&C) on the PRIM ALT. No improvement at higher RPMs. Noise is the same with either alternator.

Any ideas? The lower freqs only has to be a clue, I just don't know what it means!!

Thanks in advance for any ideas or direction.

Gordon
Lancair ES N144GP
IO-550

Gordon H. Porter
Managing Partner
Trusted Wealth Advisors, LLP
Registered Principal, Cambridge Investment Research, Inc.

800-290-2632 717-757-4908 fax 717-843-0180

GHP@TrustedWealthAdvisors.com

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