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Antenna placement

JDA_BTR

Well Known Member
I’m putting in two com antennas and a transponder/adsb antenna. I want to put the com antennas in the footwells. How far back from the spar must it be to not interfere with the pushrod for the ailerons? I assume if I’m aft of the pushrod hole all is good? And does the depth of the footwell get in the way or do I need to go further aft to avoid footwell interference? I don’t ha a delta-pop in hand to physically check it.

Is the best place for the adsb/transponder antenna aft of the battery?
 
I located mine with the BNC hole just aft of the pushrod hole; this, in turn, places it just ahead of the low point of the footwell. If you look at this photo you can see where I drew the profile of the footwell on the outside seat rib for reference when I was locating the antenna. I'm also going to use 90° BNC connectors here for good measure when it comes to clearance.

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I put my xpdr antenna just aft of the bellcrank, in order to maximize distance between it and the com antennas. Dynon wants at least 3' between them.

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Ironically todays project, and mine turned out really close to Philips. I tried to trace the footwell on the lower side skin and split the difference between the pushrods and footwell
 

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I also mounted both comm antennas under the rear seat foot wells, but mine are aft of the foot well low point.

Carl
 
I didn't think to do it before putting on the bottom skins, so now I need a rivet helper. Seems like I've seen some pictures of installations with a doubler solely held on with the antenna screws. What are the tradeoffs of that?
 
I didn't think to do it before putting on the bottom skins, so now I need a rivet helper. Seems like I've seen some pictures of installations with a doubler solely held on with the antenna screws. What are the tradeoffs of that?

I cut the holes for the transponder blade tonight. Nothing has been permanently mounted, but I can get the skin to flex side to side and can see how riveting the doubled skin would probably help. Exactly for the reason you mentioned I hoped that wouldn't be the case.
 
What location have others used for the other antennas? If I am reading the documentation correctly, a typical Dynon SkyView installation would have 4 (or 3) antennas plus GPS .

2 for SV-COM-C25 (or only 1)
1 for SV-XPNDR-261 / 262
1 for SV-ADSB-470

For the GPS portion,
At a minimum:
SV-GPS-2020

Potentially an additional
SV-GPS-250, and another GPS antenna for a certified GPS
 
What location SNIP

2 for SV-COM-C25 (or only 1)
1 for SV-XPNDR-261 / 262
1 for SV-ADSB-470

SV-GPS-2020

Potentially an additional
SV-GPS-250, and another GPS antenna for a certified GPS

What I did:
- One comm antenna mounted under the aft part of the rear passenger footwell, on the outboard sides.
- The SkyView GPS antenna on top of the glare shield but covered with a dark piece of cloth to prevent glare.
- The GTN-650 GPS antenna mounted just aft of the rear seat, under the canopy (when shut), offset slightly to one side so the canopy rail is clear.
- XPDR antenna forward of the rear seat near the centerline, but clear of the control tube. This allows for access.
- ADS-B antenna mounted just aft of the battery compartment, the ADS-B receiver mounted on a few inches away from the antenna on inside bottom skin an an simple aluminum U bracket with nutplates pro sealed to the skin. The ADS-B receiver connects to the SkyView via a single, four #22 conductor shielded wire.
- Homebrew Nav antenna in the right wingtip.
- ELT antenna is under the empennage fairing.

Did the same setup in an RV-8A. All work as advertised.

Carl
 
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What location have others used for the other antennas? If I am reading the documentation correctly, a typical Dynon SkyView installation would have 4 (or 3) antennas plus GPS .

2 for SV-COM-C25 (or only 1)
1 for SV-XPNDR-261 / 262
1 for SV-ADSB-470

For the GPS portion,
At a minimum:
SV-GPS-2020

Potentially an additional
SV-GPS-250, and another GPS antenna for a certified GPS

This is my antenna plan:

2 com antennas, 1 below each backseat footwell.

A nav antenna in the left wing tip

A TXPDR whip antenna ~36" from the 2 com antennas close to center line

An ADS-B antenna ~24" from the TXPDR antenna, also close to center line

The Dynon GPS2020 antenna under top cowl

A Garmin GPSW antenna on the aft top skin inside the canopy

I know the ADS-B antenna will be just slightly off the true vertical axis because its so far aft. But, I'm betting that to receive only in L-band, this will not be critical, just look at all the dual 978/1090mhz ADS-B receivers stuck on Cessna side windows, without an external antenna, that seem to work just fine.
 
Here's where I put them on my 8

1) Comm 1
2) Comm 2
3) ADS-B In
4) Transponder
5) SV-2020 GPS
6) Avidyne GPS

Placement takes into account the requirements in the Dynon installation manual.

I also have a Bob Archer Nav antenna in the right hand wing tip for VOR/ILS and the ELT antenna is in the passenger's right hand arm rest.
 

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Antenna Doubler - Bond It In

You can always "bond" in a doubler using a quality epoxy adhesive - 3M ScotchWeld 2216, Hysol EA9430, JB Weld, or equivalent.

I've done more than a 150 destructive joint tests using (mostly 2216) epoxy over the years, and found it provides a greater ultimate shear strength (per unit area) than a -3 riveted joint using 1 1/4" nominal spacing. Its only drawback is low peel strength - but in the case of doublers, there shouldn't be enough flex at the interface of the body skin and doubler to generate a peel type "failure".

Just Sayin' ...

HFS
 
The drawback of adhesive bonding is the lack of electrical bonding.
You lose one or more electrical bonding points from the fasteners. So, the antenna base to belly skin is all you have. I like the redundancy of multiple points.
 
Why is everyone driven to mounting the comm antennas beneath the footwells? The next area to the rear seems far more open with no pushrods or footwells to worry about.
And where are you finding the guidance on distance required between various antennas?
 
Why is everyone driven to mounting the comm antennas beneath the footwells? The next area to the rear seems far more open with no pushrods or footwells to worry about.
And where are you finding the guidance on distance required between various antennas?

Access. The floorboards aft are riveted down.
 
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