Avionics-List Digest Archive

Sat 09/19/09


Total Messages Posted: 3



Today's Message Index:
----------------------
 
     1. 01:50 AM - Re: KX155 noise-only (zwakie)
     2. 01:53 AM - Re: KX155 noise-only (zwakie)
     3. 11:48 AM - Re: Re: KX155 noise-only (Charlie England)
 
 
 


Message 1


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    Time: 01:50:52 AM PST US
    Subject: Re: KX155 noise-only
    From: "zwakie" <mz@cariama.nl>
    Hi Charlie, First of all, thanks for responding to this newbee's question! ceengland(at)bellsouth.ne wrote: > What kind of noise? Very similar to what you can hear in the WAV file in this ZIP-file, yet frequency on my radio seems to be a bit lower than in this sample: Sample White Noise (http://www.dogstar.dantimax.dk/testwavs/white.zip) So yes it is white noise. ceengland(at)bellsouth.ne wrote: > If so, does the radio's volume control have no effect on the noise volume? Negative. I did however notice that there was a slight drop in volume when pulling the COM kHz selector knob or the NAV IDENT knob. ceengland(at)bellsouth.ne wrote: > If no effect, have you checked the nav section's volume? Not sure if I have this checked, will do it next time at the hangar. ceengland(at)bellsouth.ne wrote: > If it's not white noise, and the nav volume is in fact turned down, and > the comm volume is in fact turned down, is it a hum or buzz? Don't know, will check as well. ceengland(at)bellsouth.ne wrote: > If so, is it still there if you unplug your mic cord? Don't know either, will have to check. ceengland(at)bellsouth.ne wrote: > If so, it might be that the audio output of the radio really does have a problem. Let's hope we won't have to reach that conclusion [Wink] Thanks. Marcel Read this topic online here: http://forums.matronics.com/viewtopic.php?p=263799#263799


    Message 2


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    Time: 01:53:14 AM PST US
    Subject: Re: KX155 noise-only
    From: "zwakie" <mz@cariama.nl>
    Come to think of it, could it be something as simple as some wiring gone loose or terminal-connection breaking up? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=263800#263800


    Message 3


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    Time: 11:48:31 AM PST US
    From: Charlie England <ceengland@bellsouth.net>
    Subject: Re: KX155 noise-only
    Charlie England wrote: > Being new to maintaining and troubleshooting issues with avionics, I > am kind of hoping someone can put me in the right direction to get my > NAV/COM set working again. > > My KX155 stopped functioning. All that I am getting now is noise in > the headset. Not getting my voice echoed either. I've tried all > variations for squelch and volume, on radio, headset and intercom - > nothing but noise at every possible combination. > > When pressing the PTT-switch, the "T" for transmitting is showing, but > I can't state for a fact that it actually is transmitting (I will test > that on a dummy frequency using my handheld radio as a receiver the > next time at the hangar). > > Does anybody have any suggestion to the most likely causes please? > > Thanks. > Marcel > > > zwakie wrote: >> >> I just returned from my aircraft and tested transmission, using a >> handheld as a receiver. >> >> The radio IS still transmitting, so the problem is outputting to the >> headset through the intercom. >> >> > > Hi Marcel, > > I pasted your 1st message into this one to get all the symptoms together. > > What kind of noise? Is it 'white' noise like you'd hear on an AM > radio tuned between stations, or an old TV set to an empty channel? If > so, does the radio's volume control have no effect on the noise > volume? If no effect, have you checked the nav section's volume? I've > actually seen this happen to people on a couple of occasions with > combo nav/comms. The nav (noise) volume can overwhelm everything else > in the radio. > > If it's not white noise, and the nav volume is in fact turned down, > and the comm volume is in fact turned down, is it a hum or buzz? If > so, is it still there if you unplug your mic cord? If so, it might be > that the audio output of the radio really does have a problem. > > Charlie > > >>Come to think of it, could it be something as simple as some wiring gone loose or terminal-connection breaking up? Marcel, To get help in troubleshooting, it's helpful to keep the communications (and troubleshooting steps/results) together and in sequence. If someone new sees one of the posts & wants to help, they need to see all the symptoms & what's already been tried. One thing I forgot to mention in the previous post is to simplify the system. You mentioned 'problem is outputting to the headset through the intercom'. Have you turned off the intercom while checking? If the system is set up correctly, the radio should be audible through the pilot's headset with the intercom turned off, and you should be able to transmit with it off, also. With the intercom in the circuit, that's an extra component that could be causing your problem. Another thing I forgot to mention that may be a really quick check, is to find another a/c with the same radio & swap yours into the other a/c's radio tray. If your radio actually has an internal problem, you'll get the same symptoms in the other a/c. If the problem is outside the radio (installation or a different component, like the intercom), then your radio will work normally in the other a/c. Charlie




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