Intermittent radio?

[kswans1314]

EDIT: I found my ghost.. I pulled the bottom panel off to get ready to replace the antenna only to trace the cables and find the last time the shop worked on my brakes they apparently connected the Comms cable to the ADSB blade antenna and the ADSB cable to the Comms antenna... It is unbelievable how much better my radios work now..

 

[Bob Turner]

Tell us about your antenna and antenna cable. Read the numbers on the cable - should be either RG-58U or 400.

Internal dipoles are extremely directional, and I have fixed one airplane that had RG-59 cable (Radio Shack).

 

[Bob Turner]

Oh - I too use type and color at uncontrolled airports. But with ADS-B, a lot of tech-savvy pilots are relying 100% on the iPad for traffic separation. They will bust your chops for not using your N-number.
Doesn't work for my grandfathered Cubs.

 

[kswans1314]

I know I replaced any old cables with 400 or whatever the new stuff is at annual when we replaced the transponder. I will confirm which parts I have later though.

Most all of the instructors on my field are fresh out of aviation schools on the way to the airlines. Most not even old enough to buy a beer. They fail to understand that radios calls while critical for safety and separation are also not even a requirement on our field. Some of them act like they fly out of DTW already...Made even more explicitly clear by the shape of their traffic patterns.

 

[kswans1314]

Confirmed new RG400 cables. Attached a picture of the antenna, not sure the model but told it was in good shape. Looks to me that the cap isn’t quite snug, could water get in there and cause damage somehow?

 

[Bob Turner]

See those big steel gear legs? Their secondary function is as parasitic arrays. Move your antenna to the top. There is a special pad up there, but on one of the wing fairings gives a better ground plane.

 

[kswans1314]

I had a feeling antenna location or interference could cause intermittent issues. It sounds like a reasonable place to start digging. Thanks.

I don't see why not, but it should be possible to add a second antenna on top and tie the two together correct?

Currently it looks like my gps antenna and beacon are taking up the available space out back.

 

[Bob Turner]

Multiple antennae are what you should try to avoid. Space them far enough apart and you minimize parasitic effects.

Theoretically, a 1/4 wave stub on an infinite ground plane gives you a toroidal antenna pattern that is as good as a dipole, at least laterally. We approximate that by separating antennae by six feet or so. A ground plane several feet in diameter approximates the infinite plane, and can be just a bunch of tubes, wires, and ribs.

Those gear legs make the antenna pattern look like fingers in a glove. Lots of power in the fingers, and almost zero power in between. At the wrong angle, no transmission and poor reception.

 

[kswans1314]

Wow, ok, not how I would have imagined that working but makes sense.. Sounds like relocating the gps antenna then putting the radio antenna in its place will be the best place to start.

 

[Bob Turner]

The GPS antenna is fine where it is - using the wings for the comm ground plane is a little better than that six inch square aluminum pad on a wood structure.
But the pad is ok - that’s where Bellanca put the comm antenna. Nah - do the wing root.

 

[kswans1314]

Alright Thanks again! What exactly is there to mount too? The wing root fairing itself seems pretty flimsy.

 

[Bob Turner]

Use a doubler. There isn't a lot of force on the typical antenna.

I put a huge venturi on the side of my Dec, expecting it to crack in a hurry without a doubler. That was 18 years ago. I am often at 160 mph coming home.

 

[kswans1314]

Sweet thanks, I’ll report back with an update

 

[Goodyear]

Sweet thanks, I’ll report back with an update

I had a similar problem on my #2 radio. Turned out to be a ground wire. Wouldn’t transmit but received fine. Then I developed a problem with #1 radio. I was missing calls from Tower. Turns out the connection from the radio to the connector in the rack was loose. Had both radios removed and the racks redone.

 

[kswans1314]

I had a similar problem on my #2 radio. Turned out to be a ground wire. Wouldn’t transmit but received fine. Then I developed a problem with #1 radio. I was missing calls from Tower. Turns out the connection from the radio to the connector in the rack was loose. Had both radios removed and the racks redone.

Wire connections are high on the list of things to check out too

 

[kswans1314]

Note to self: Trust but verify.

 

[Bartman]

glad to hear you got it fixed.