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7A and 9A Owners, Transponder antennas Where to mount??

R

ron sterba

Well Known Member
Hi Guys, Well time has come to mount my 3 antennas, Transponder,ADS-b and com antenna on my RV9A. Using the Skyview 10" and Ads-b TRANSPONDER and one ICOM 210. LOOKING AT LOCATIONS YOU FINE FAVORABLE for these antennas.

Thanks
Ron in Oregon
 
The comm in our 7A is under copilot seat and xpndr is just aft of firewall forward of copilot feet. No issues.
 
I mounted xndr antenna between the pilot pedals and comm2 just fore of main spar copilot side.
Transponder is OK. Transmitting on comm2 gives audio back on the radio. So maybe in that location is not so good.
For xndr installation, see my website.
Ciao
 
Com is just foreward of the spar, pilots side. Transponder same position
co-pilot's side. No need to route coax through the spar.
 
X-ponder: Stub antenna under the right main gear mount.
ADS-B: blade antenna under the first inspection plate on left wing.
COM1: Belly Bent antenna under the pilot seat.
COM2: Copper foil antenna (Van) on the windshield (in the picture below I still had a homemade belly bent antenna on the right side forward of spar).
The 3rd homemade belly bent antenna on the left side is for APRS.

antennas09.JPG
 
I have only two xpdr and comm. Here they are. Easy to reach/inspect and within cable length specs. Never had issue on transmitting/receiving.








 
Thanks for the pictures,sure helps.Like the idea of NOT running the coax cable thru the spar. Ok this saves me time and wire. Now I just learned that the two antennas (Transponder and ADS-B blade antenna) need a separation of several feet from each other. I 'll have to check into this or if anybody else knows the minimum distance, let us know.Thanks Guys!!
Ron in Oregon
 
I am planning on two comms, transponder and ADS-B.
I have planned for the two comms under the seats just behind the spar. Blade transponder right side just behind the firewall and the ADS-B blade behind the baggage floor. I think this is the best I can do for proper seperation.
 
As I recall ....

... there's also supposed to be 3 feet between the x-ponder and com antennas. My com antenna is on the centerline aft of the spar. Since my center section came with two pass-thrus on either side of the center tunnel, running the coax up to the panel was no sweat.
 
COM1 bent whip below the righthand baggage compartment bay, close to the center tunnel. excellent functionality.

XPDR stub antenna just beside the fuel vent in the front right bottom skin. working great!

COM2 used elt antenna mounted to the inside/rear of the rollover bar on the righthand side. dismal performance. would look for alternative location next time. works ok for short range on ground / formation in the air. but e.g. very poorly for atis reception.

3 GPS antennas on the glareshield. working great.

FLARM short stub 2.4ghz antenna opposite to the COM2 on the lefthand inner side of the rollover bar. again appears to be a poor location, not getting as much reception as would be ideal. may rewire this one of these days.

so in general, stay away from the rollover bar / inside cabin other than the glareshield if possible.
 
Thanks!

Hi Bernie

Thanks for your input ;-) will do it like:

- The transponder in the lower right corner, beside the fuel vent.
- COM1 on top, rear fuselage.
- COM2 on bottom between fornt and rear spar.
- ELT behind roll over bar (not ideally, but in a flipped condition, there is hopefully still a "window to the sky".
- FLARM on glareshield.
- GPS: 1x on glareshield, 2x FWF.
 
2xCOM, 1 XPDR, 1 ADSB

I spent some time with the Garmin manuals and selected locations that nearly meet all the requirements:
Transponder far aft in the tail, just forward of F-710 bulkhead.
ADSB just aft of the baggage bulkhead.
2x COM antennas just aft of the main spar, in between the outboard most seat ribs on either side.

My plane isn't flying yet, so I can't comment on performance.

More info here.
 
Last edited:
OK I checked on the coaxial cable called 400 something. Non burnable, are you ready for the price?????? $8 a foot,,, darn, I think I'll stay with the R 58, think thats the one that works just fine for all the antennas,

Ron in Oregon
 
ron sterba said:
Hi Guys, Well time has come to mount my 3 antennas, Transponder,ADS-b and com antenna on my RV9A. Using the Skyview 10" and Ads-b TRANSPONDER and one ICOM 210. LOOKING AT LOCATIONS YOU FINE FAVORABLE for these antennas.

Thanks
Ron in Oregon
Click to expand...

A while back I did a little write-up on antenna placement. You can read it here:
http://www.kalinskyconsulting.com/rvproj/antennas.htm

ron sterba said:
OK I checked on the coaxial cable called 400 something. Non burnable, are you ready for the price?????? $8 a foot,,, darn, I think I'll stay with the R 58, think thats the one that works just fine for all the antennas,

Ron in Oregon
Click to expand...

RG-400 is superior to RG-58 in RF performance and flammability characteristics, and has long ago replaced RG-58 as the modern standard.

Not sure where you looked to find it at $8 / ft. I just checked the first two sources that came to mind, B&C and SteinAir, and they both sell it for under $3 / ft. Best price I've seen recently is from B&C at $2.35 / ft.
 
flyvans.com said:
XPDR stub antenna just beside the fuel vent in the front right bottom skin. working great!
Click to expand...

Xpdr needs a ground plane approx 8" dia (4" from the edge).

mcencula said:
I spent some time with the Garmin manuals and selected locations that nearly meet all the requirements:
Transponder far aft in the tail, just forward of F-710 bulkhead.
Click to expand...

Xpdr antenna should be kept as short as practical, 8' is the max with the garmin units (with RG400).
 
I mounted the transponder and ads-b antennas just behind the 705 bulkhead/rear wing spar.

photo04.JPG


Both transponder and ads-b boxes are mounted under the baggage floor just a few inches from the antennas. My lower comm antenna is mounted just forward of the 707 bulkhead. Not flying yet but they work in my garage.

photo05.JPG
 
Nice job Larry! I hadn't thought of mounting the units in the floor but a real eye catcher. You got me thing'in know. Neat idea my friend.

Ron in Oregon
 
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