COM reception problems

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Pascal
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COM reception problems

Postby Pascal » Mon May 15, 2017 12:28 am

On my DA20-C1 1999, the main radio is a Bendix King KX 125. When communicating with various ATC, sometimes I get excellent transmission, and sometimes I hear horrible garble with lots of noise and I can barely if at all understand what they are trying to tell me.

It happened to me a few weeks ago when I made initial contact with Toronto Centre at 2000 feet near Brantford, Ontario, and again this week-end, when talking to Montreal Centre from CYHU, which is really not that far from them. Sometimes I hear them loud and clear, and I know they hear me perfecly, but sometimes I only hear garble and I need that problem solved asap.

Anyone else has experienced such a problem, and if so, what was the root cause of the problem and the solution?

Also, does cloud cover affect radio transmissions?

Thanks,

Pascal
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RMarkSampson
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Re: COM reception problems

Postby RMarkSampson » Fri May 19, 2017 12:35 am

Pascal,
There are only a couple of things you can trouble shoot yourself. Ensure the radio is seated firmly into its cradle, clean the contact points for the electrical connectors, ensure the antenna connections are not coming loose. See it happens if the engine is off. I have two GNS 430s that have given me intermittent problems. On a few occasions one radio (normally COM1 for me) gets noisy - i.e. the RX lights up and static is heard near continuously. Cycling that radio to off for a few minutes sometimes clears the problem. Otherwise, sometimes it just seems to fix itself after I go to the other radio for a while. I think it is also heat sensitive so the problem seems to get worse during the summer months.

Ultimately, there is not much you can do other than find a good Avionics Shop to take your problem to. Happily, I have several in the area where I live and they have the bench equipment to check out the problem. They can locate electrical interference coming from the engine (mags) etc. They will also "send it off" to the factory service guys if it is not within their ability to solve. Good luck, electronic issues are pesky problems that make you feel the most hopeless in solving.
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Re: COM reception problems

Postby Spinner » Fri May 19, 2017 2:15 pm

Had an issue with a 430 being noisy. Every time we did something it would fix the radio for a flight or more. After multiple radio and audio panel changes, re-racks etc. went back and looked at maintenance history. Found that we had changed a turn and bank about the same time as the issues started. We removed and installed another turn and bank and the issue has not reappeared (as he says a quiet prayer).

Paul
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Re: COM reception problems

Postby danno2000 » Sat May 20, 2017 9:03 pm

I was having a very similar problem sporadically and today I think I figured it out. The air vent was pointed on me, and the rush of air from the vent was getting picked up on the mic on my headset. It created an unending stream of static-ish noise. When I reduced the vent airflow, the problem went away.

Hope yours turns out to be that easy!

Good luck,
dan
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Re: COM reception problems

Postby Pascal » Sun May 21, 2017 3:41 am

Thanks guys. I will go to the airplane tomorrow with electrical contacts cleaner spray that I purchased in the automotive department at Canadian Tire's. I will remove and put back the radio. Hopefully that will solve it.

I never experience the problem on the ground. Only in the air. And only when receiving, when ATC is transmitting. I hear them talking to me, but it's so garbled that I can barely understand my call sign. At least I still got COM2 in the meantime. Even when I have this problem receiving, I have confirmation that ATC hears me loud and clear.

It has been raining cats and dogs for the last two months here, maybe there is some moisture on the Coax or the contacts. It's been sunny for the last few days, maybe that will have helped evaporate that moisture.

If I can't solve the problem tomorrow, I'll fly the plane to an avianics shop. Hopefully I can get this fixed quickly and enjoy my plane.

Thank you all for your help, much appreciated.
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Re: COM reception problems

Postby Pascal » Sun May 21, 2017 11:13 pm

Problem solved!

Today I went to the airport. Unscrewed the KX 125 radio using a 3/32 allen key. Removed the radio from the tray. Cleaned the contacts with electrical contact cleaner spray that I had purchased at Canadian Tire. I also sprayed the contacts at the end of the radio tray, including the antenna connections. Placed the radio back in its tray and rescrewed it using the allen key.

Performed a radio check with the tower, all good. Filed a flight plan. Took off to the nearby Bromont airport CZBM to pick up a friend. Refueled. Took off again to sample the tasty food at the Sherbrooke CYSC airport. Turns out on a Sunday late afternoon all you can have there are soda and chips from the vending machines. Returned to CZBM to bring back my friend, and then another short hop to my homebase CYJN.

Total cost fo the operation: one can of electrical contact cleaner spray for 7$ canadian plus taxes. Roughly 5$ usd.

I am relieved to know that I now have two fully operational radios and that I won't have to bleed cash to fix the problem.
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Re: COM reception problems

Postby Colin » Tue May 23, 2017 12:23 am

Best soda and chips all month, I imagine.
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Re: COM reception problems

Postby Derek » Sun May 28, 2017 12:12 am

Hahah, small world. Same thing happened to me last summer. I flew Toronto to Nova Scotia and Sherbrooke is the perfect half way point to add/subtract fluids and grab a bite to eat. The Montreal smoked meat sandwich and the service was unexpectedly spectacular! I was so excited coming home to stop in Sherbrooke again that I didn't bother eating lunch before I left as I was pressed for time to get home. My mouth was watering for a great meal when bam - it's Sunday and I find out the restaurant isn't open. I see the vending machine and after hunting through my luggage manage to scrape up enough change for a tiny bag of peanuts. I filled a water bottle in the washroom and ate peanuts for dinner. 6.5hrs flying time with nothing but a few peanuts. I landed very hungry!!
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Re: COM reception problems

Postby Colin » Sun May 28, 2017 3:49 am

Look at the size of you. That must be your usual meal size. Dunno how you reach the rudder pedals.
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Re: COM reception problems

Postby 1911Tex » Mon Jun 05, 2017 1:39 pm

Pascal: Did your com problem go away? I have a similar issue with my 430....only on the ground away from the tower. Barely understandable. Sent back to Garmin returned like new...same problem. New antenna, same problem. Connections tight, same problem. Sprayed with electronics cleaner, same problem. Probably the least or no cost solution is in the forest of trees.

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