Radio static

T

Todd Wilson

Filing Flight Plan
Joined
Jul 12, 2018
Messages
27
Display Name
Todhog
Hi everyone, my name is Todd and I have a question.

Recently it seems my radios have static when receiving weaker transmissions. Very strong transmissions are clear as can be. This is with the engine off and in flight. It’s both radios (KX155) and all headsets which are Bose A30s. The intercom is clear as well. Any ideas?
 
Make sure the antenna has not departed the airplane. If still there, make sure it's not covered in grease or oil, or loose...
 
Both antennas are there and they are on the roof so they are clean. Remember, whatever the cause is, it is effecting both radios the same. I don’t think it’s the radios either.
 
With this being both radios, I would look for an external source. New phone? New usb power adapter (old ones can die too). Try removing power from anything like that and see if that helps. If not, some deeper debugging is needed
 
Even if the antennas look ok, it can be corrosion under the base. Sadly, some have to have rivets drilled out.

A very savvy tech can diagnose this before that happens.
 
Initial Fix said:
With this being both radios, I would look for an external source. New phone? New usb power adapter (old ones can die too). Try removing power from anything like that and see if that helps. If not, some deeper debugging is needed
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Could be the USB port, I put the cheap one sold for boats and experimental aircraft in the cigarette lighter hole. It was only $29 at Spruce. I could pull the beaker on it.
 
Tools said:
Even if the antennas look ok, it can be corrosion under the base. Sadly, some have to have rivets drilled out.

A very savvy tech can diagnose this before that happens.
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There are two antennas and the static is the same on both radios but that’s a possibly. The thing is, the static is only on weak signals. Planes far away on Unicom are the worst, planes nearby are perfectly clear. AWOS starts out with static but gets clear as I get closer. Maybe it always did this but it seems like a new thing to me. I just started being annoyed by it so I feel like it’s new. Could be my imagination. ‍‍
 
Todd Wilson said:
There are two antennas and the static is the same on both radios but that’s a possibly. The thing is, the static is only on weak signals. Planes far away on Unicom are the worst, planes nearby are perfectly clear. AWOS starts out with static but gets clear as I get closer. Maybe it always did this but it seems like a new thing to me. I just started being annoyed by it so I feel like it’s new. Could be my imagination. ‍‍
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That kind of sounds like just the way it works - closer signals are stronger so they're clearer. I don't know that there's anything necessarily to be fixed.
 
If it’s attenuating the signal, which can happen with a mismatch (ie the kind of thing corrosion on the ground connection does) this normal phenomenon would be greatly exaggerated.
 
RussR said:
That kind of sounds like just the way it works - closer signals are stronger so they're clearer. I don't know that there's anything necessarily to be fixed.
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Yeah, maybe it was always like this, I’m getting old so it’s hard to remember.
 
Todd Wilson said:
This is with the engine off
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Start here as this tends to point to a grounding issue or an RF problem without the engine running.
Has there been any work performed or have you changed anything cockpit area prior to the static was noticed?
Do you have resettable circuit breakers?
Do you have a separate avionics master switch?
How many headset jack points are there?
Do you have access to a different type headset for testing purposes?
 
KX-155s are analog radios. Could it be that squelch is simply doing its job? When you say "weaker transmissions", are they far away? Are they from one or two specific transmitters (like that AWOS station 20 miles away behind a hill)?
 
They are from planes miles away on 122.8. It just gets annoying listening to their scratchy transmissions. After some research it may be that the squelches are set too low allowing too weak of signals in that should be filtered out and I’ve got a guy that can look at it. I think my real problem is too many years in 121 and now I expect the same level of perfection in GA. But, thanks for the help guys.
 
Todd Wilson said:
There are two antennas and the static is the same on both radios but that’s a possibly. The thing is, the static is only on weak signals. Planes far away on Unicom are the worst, planes nearby are perfectly clear. AWOS starts out with static but gets clear as I get closer. Maybe it always did this but it seems like a new thing to me. I just started being annoyed by it so I feel like it’s new. Could be my imagination. ‍‍
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Do you also have static on the NAV radios?
 
Todd Wilson said:
I don’t know, I haven’t used those since GPS was invented!
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That may be, but they receive buy they have a voice feature to receive AWOS at some locations. If you are ceiling the static on the nav radio, it isn’t the comm antenna.
 
Clip4 said:
That may be, but they receive buy they have a voice feature to receive AWOS at some locations. If you are ceiling the static on the nav radio, it isn’t the comm antenna.
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If I can find one of the AWOSs I’ll give it a try.
 
Clip4 said:
That may be, but they receive buy they have a voice feature to receive AWOS at some locations. If you are ceiling the static on the nav radio, it isn’t the comm antenna.
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Or just listen to the ID on the VOR freq.

Nauga,
livin' on Channel Z
 
Yes,yes,four and yes. Tried different headsets and the speaker, all the same. Probably need new radios.
 
I’m leaning towards the squelch, if it could weed out those distant aircraft it would be fine.
 
Todd Wilson said:
I’m leaning towards the squelch, if it could weed out those distant aircraft it would be fine.
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Maybe start with the battery on, avionics on but only that radio, and start pulling CBs to see if you lose the static with only one non-Bose headset plugged in?
 
Bell206 said:
Maybe start with the battery on, avionics on but only that radio, and start pulling CBs to see if you lose the static with only one non-Bose headset plugged in?
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I’ll give it a try, hopefully tomorrow.
 
Todd Wilson said:
This is with the engine off and in flight.
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Please reveal your gas saving secret of flying with the engine off :)

There are many avionics shops that should be able to adjust the squelch to filter out the weaker far away signals. But far away signals will be scratchy by definition if squelch is set to allow a weak dB level to pass through. -91dB carrier squelch opening is, according to one install manual, the typical setting for many COM radios. You could always raise it a bit if not wanting to hear half the country on 122.8.
 
I’m thinking that’s the problem. It may have been this way all along and I just started noticing it. I tried pulling breakers but nothing changed and I made a video with my phone utilizing the speaker but I couldn’t get it to upload. In it you can clearly hear the difference between aircraft.
 
Please reveal your gas saving secret of flying with the engine off :)

Man I wish I had one with the price of gas these days.
 
How "weak" are the transmissions you're hearing the static on? It may be a totally normal reception of a weak transmission. Have you heard of the 5/5 quality of a tranmission?
 
The scratchy signals are weak and far away, you are probably right. It may be 40 years of 121 flying that has made me expect 5/5 signals 99% of the time. It’s 122.8 that is the most annoying on the weekends. I can say that both radios are exactly the same.
 
So I’ve been flying a bit the last couple days and what I found is pretty much all transmissions I receive have a bzzzzzt sound during the transmission. Only very close and strong transmissions are totally clear so I’m guessing it’s in my radios somewhere. It’s the same in both radios but the intercom is clear between pilots.
 
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