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Routing WH-00014 UAT Antenna Cable & W-00059 Phone Cable Thru Main Fuselage

avatty

Well Known Member
Having put off joining the fuselage halves until I finally could have a helper ....
Is there guidance in the KAI for routing the above items through the main fuselage? If there is I still can't find it.

The routing seems pretty straightforward - both run from the aft fuselage forward on the right side, one rib bay out from the central bay. Between the flaps tube and the spar, route into the center area through the bushing clip then straight ahead through the wing spar and up the central ramp alongside the forward fuel line.

Please let me know if any of this is incorrect. Thanks!
 
Check yourself...

Fast forward in the plans to section 26-11, see Figure 1.

If you are going to use a 1090ES unit (e.g. Garmin GTX345, GNX375) the antenna goes under the baggage compartment, and not in the tail...save yourself the hassle of running that wire.
 
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Thanks, through routing the rudder cables I realized the above description is in error. The antenna and phone cables both run up the center, the rudder cables use the outboard holes.

Mostly I was concerned about installing the baggage floor then not having access to wiring, but that looks like its not a concern.

Onward!
 
Fast forward in the plans to section 26-11, see Figure 1.

If you are going to use a 1090ES unit (e.g. Garmin GTX345, GNX375) the antenna goes under the baggage compartment, and not in the tail...save yourself the hassle of running that wire.



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This is what I did to cover the hole. I can remove at a later date if I change my mind…
 
I have a GNX-375 with a CI-105 mounted in the aft tail cone location & have not any issues.

Cool -- That's good to hear.

Unfortunately, that doesn't meet installation requirements and as a result the required output power will (should - mathematically speaking) suffer.

Just out of curiosity have you done a transponder test in accordance with 91.413 & meet the parameters in Part 43, Appx F? It would be interesting to see what the actual radiated power is (125W or 70W depending)...
 
I put the antenna for a GTX-45R in the tail, w/ no issues - followed Van's instructions and noted several other builders who did the same. Seems to work just fine.

_Alex
 
I put the antenna for a GTX-45R in the tail, w/ no issues - followed Van's instructions and noted several other builders who did the same. Seems to work just fine.

_Alex

What was the length of the RG-400 (or similar) from the GTX-45R to the Antenna?
 
Of interest, you can mount and ADS-B antenna in the tail location, then mount the SkyView ADS-B receiver near it. The receiver is connected to the SkyView serial input via a four #22 conductor shielded wire - no issue with connector length for any RV application.

Carl
 
Cool -- That's good to hear.

Unfortunately, that doesn't meet installation requirements and as a result the required output power will (should - mathematically speaking) suffer.

Just out of curiosity have you done a transponder test in accordance with 91.413 & meet the parameters in Part 43, Appx F? It would be interesting to see what the actual radiated power is (125W or 70W depending)...

Yep - checked out fine. Sorry I didn't receive a detailed report with my xponder /static check.

Lot's of things we do/don't do are based on theoretical calculations. The actual length of the cable falls just over of the length Garmin specifies as the max due to the calculations you speak of. I checked with two reputable avionics installation shops whom both said it should be no problem. If it didn't work what did I have to lose? An hour relocating the antenna under the baggage, rerouting and trimming the cable? So far, so good.....
 
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One other consideration - for a tail dragger this antenna is, in my opinion, too far aft thus too close to the ground.

Carl
 
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It is a bit far aft isn't it; I could see it causing issues working under/around the tail, especially if you opted for the DP ULD version (read: sharp!)
 
What was the length of the RG-400 (or similar) from the GTX-45R to the Antenna?

I used what came stock with the empennage kit; not sure of the length, but it is RG-400, was produced for Van's by SteinAir, and was already terminated with BNC connectors.

_Alex
 
Cool -- That's good to hear.

Unfortunately, that doesn't meet installation requirements and as a result the required output power will (should - mathematically speaking) suffer.

Just out of curiosity have you done a transponder test in accordance with 91.413 & meet the parameters in Part 43, Appx F? It would be interesting to see what the actual radiated power is (125W or 70W depending)...


Mine was also tested per FAR 43 appendix F (avionics shop didn't provide a detailed report). Just another data point for those builders who are now questioning whether or not to use the Van's-suggested tail location; in service, it seems to work fine.

_Alex
 
The answer is not a straight forward as it might seem. The installation manual for my GTX45R has the following requirements (only posting the relevant ones to this discussion):
• Be attached away from major protrusions, such as engines, nacelles, propellers, and antenna masts.
• Not be attached within three feet of the ADF sense antenna or any other communication antenna
• Be attached to a minimum of three feet of cable from the GTX 35R/45R to prevent RF
interference.

If you mount the antenna on the belly vs tail, you will not meet the first 2 requirements and possibly the 3rd depending on where you mount the unit.
For the record, my antenna is in the tail location and I have had no issues and had all green checks in my ADS-B report.
 
only posting the relevant ones to this discussion.

There should also be a chapter on Transponder Antenna Location, in the GTX 3xx Part 23 AML/STC it's chapter 3.10.2.

If you fly in airspace around densely populated areas, you probably will not experience issues and certainly all the care-abouts in the PAPR (NIC, NACp, NACv, SIL, SDA, etc.) won't be adversely effected by this issue; WHEN the emitter is received, its data is good.

Remember the inverse square law dealing with RF. The aircraft may not be "heard" by distant stations because the GTX transmit power has been attenuated by the cable, *AND* the GTX may not "hear" the interrogations from distant sites for the same reason.
 
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