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I am at the stage of my fuselage construction where it is time to consider where to ut the COM, Transponder, and ELT antennas I bought at Oshkosh this year.

I am building a taildragger Sonex and am interested to hear from those that have completed this.

Where did you place the antennas?

What kind of doubler setup did you use?

Where did you route the coax cable?

Anything you'd do differently?


Robbie
Sonex 1517

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I'll try to help a little here. When I first started flying, my COMM antenna was on my glareshield with the antenna routed to follow the contour of the windshield bow. All I can say is don't do this! I had bad reception this way. After i started flying I moved the same COMM antenna to the top of the turtledeck, right next to the center spine, around 12" behind the canopy. Reception was improved dramatically and I've been happy with it ever since. I routed the coax cable to run right behind the first turtledeck bulkhead (right behind where the passenger's head would be) and then forward along the rudder cable. The only doubler I used was a big fender washer with a slight bend put in it to follow the contour of the turtledeck. i hated to add lots of rivets up there and thus far, it's worked great.

I mounted my ELT in the "baggage area" (the first bay of the rear fuselage) and mounted my antenna on a top bulkhead pointed aft. The ELT antenna has a small angle in it (for external mounting I'm sure) and followed the outer skin perfectly. I'm sure I'll catch trouble for having my ELT antenna mounted internally, but it works for me! That way i could run my ELT coax cable a few inches from the ELT itself right to the antenna.

I don't have a transponder but if i did, I would follow the example of most others and mount the small transponder antenna behind the spar tunnel under the seat someplace. Someday I'll add one, and that's where it will go!

This is just what I've done...certainly doesn't make it right, but it's working for me! Glad to hear you're making progress Robbie!!

Thanks Mike!

Working on the turtledeck now....


Robbie
Sonex 1517

Sent from my iPad using Tapatalk HD

Robbie...

-Comm on the top
-Transponder on the bottom
-ELT under the baggage area

Routing wiring is straight forward as there is plenty of room under the seat and the sides offer 1 inch of stand off from the skin to the upholstery to hide wires.

So far so good but I have not tested the ELT's full capabilities... :D

Thanks Kip!


Robbie
Sonex 1517

Sent from my iPad using Tapatalk HD

I'm building a tri gear model and want to locate the com antenna on the bottom of the fuselage, probably behind the cockpit with the xpndr antenna just ahead of the spar. Can anyone comment by experience as to reception/transmit with a bottom antenna location. Thanks.

David
ONEX 28

I tried bottom mount comm antenna initially, wanted to keep the top 'clean'. That was good for one flight! Problem is, unless you're at a big flat airport, you can't talk to the tower. We're at a small grass strip inside a class D airspace and tower couldn't hear me until I was airborne. Bottom is fine once in the air.

I mounted an antenna on top and now comm with tower, while I'm still on ground is great. I left the bottom antenna and connected a bulkhead BNC female to the panel and use it for backup handheld. (Actually got to use the handheld once and it worked fine)

Here's mine:




It's that real cheap antenna from Spruce, I'll see how I go with it but on first tests it seemed to perform great.

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Sonex1517 wrote:I am at the stage of my fuselage construction where it is time to consider where to ut the COM, Transponder, and ELT antennas I bought at Oshkosh this year.

I am building a taildragger Sonex and am interested to hear from those that have completed this.

Where did you place the antennas?

Comm on the turtledeck, just behind the canopy. Has worked perfectly in the air and on the ground. Transponder is in the bottom skin, just forward of the rear spar carry through.

Sonex1517 wrote:What kind of doubler setup did you use?

Just an extra layer of .032 aluminum for the antenna to go through. The antennas usually come with instructions for mounting, including the doubler type and dimensions.

Sonex1517 wrote:Where did you route the coax cable?

My comm cable runs from the panel, down the side of the fuselage vertical angles, then along the port side, just below the level of the seat cushion, at the horizontal fuselage angle, then up to the top of the turtledeck. The transponder coax runs in parallel with the comm coax, to the panel.

Those are the ONLY wires on that side of the aircraft. All other wiring that runs from the front of the cockpit to the rear, are on the starboard side, to prevent interferences.

Sonex1517 wrote:Anything you'd do differently?

I would have ordered my coax cables an extra 12" beyond what I "thought" I needed. When you actually run them and secure them, somehow they get shorter ;) .

I used Click-Bond fasteners to secure all my wiring. They are held on with a special expoxy that will not come off, and so I didn't put extra holes in the aluminum to make anchor points. Highly recommended. You'll see them often in my Kitlog posts for the avionics.
http://www.clickbond.com/modules.php?na ... egoryid=93