IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM - Poor radio reception and transmission IFD540

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Poor radio reception and transmission IFD540

Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=2189
Printed Date: 27 Apr 2024 at 8:48pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Poor radio reception and transmission IFD540

Posted By: baldcaldwell
Subject: Poor radio reception and transmission IFD540
Date Posted: 25 Apr 2021 at 8:55am

We are almost ready for the first flight of my Bearhawk Model B. I've been doing some taxi testing as well as calling for radio checks. Those that can hear me are relatively close. Near the runway the ASOS antenna is about 2500' away and in my line of sight. I cannot hear the ASOS unless I have the squelch on. We did a high speed taxi test down the runway. The plane behind me on the taxiway heard my call to take the runway. However when I turned off at about 4,000' he could not hear me when I called to clear the runway.

A friend of mine called his avionics buddy. He suggested that I install a ground strap to one of the mounting bolts to my belly mounted Comant VHF CI-122 antenna. Effectively grounding the antenna to the airframe. I did. This did not change anything. I am still having trouble receiving and transmitting.

I am using RG400 coaxial cable and RG400 BNC fittings.

Today Amazon is delivering a SWR meter and I will test the signal at the antenna BNC connection.

Any thoughts?

Thank you!

-------------
Rob Caldwell
Lake Norman Airpark (14A), North Carolina
EAA Chapter 309
Model B Quick Build Kit Serial # 11B-24B / 25B
YouTube Channel: http://bearhawklife.video
1st Flight May 18, 2021

Replies:

Posted By: wookie
Date Posted: 14 May 2021 at 12:54pm

Has to be something in the antenna/connections as both xmit and receive are both affected. BH

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BH

Posted By: PA23
Date Posted: 14 May 2021 at 1:45pm

I'm assuming this is in your Bearhawk. where is the antenna mounted? I think the fuselage is fabric covered isn't it? Did you make provisions for a large enough ground plane? I think you need a ground plane just over 2ft in diameter, on an all aluminum airframe this isn't an issue but on a fabric aircraft this has to be taken into consideration.

Posted By: baldcaldwell
Date Posted: 14 May 2021 at 1:54pm

Good stuff everyone! We have resolved the RX/TX issue and are back up and running! Move the antenna up the tunnel. Here's the discussion: https://youtu.be/GHjPTiy5ViI?t=96" rel="nofollow - https://youtu.be/GHjPTiy5ViI?t=96

Thanks for the help!

-------------
Rob Caldwell
Lake Norman Airpark (14A), North Carolina
EAA Chapter 309
Model B Quick Build Kit Serial # 11B-24B / 25B
YouTube Channel: http://bearhawklife.video
1st Flight May 18, 2021