Ironflight

Ironflight

VAF Moderator / Line Boy
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I'm looking for anyone who has actual flight experience with the 430W in their RV-8 in regards to antenna placement. I have been flying the "straight" (non-WAAS) 430 for over five years with the antenna under the cowl, and have never once had a drop-out - it works great!

I am planning on upgrading the 430 to the "W" configuration to provide database commonality with our -3 (which has the "W" - can't get a straight 430 from Garmin anymore), and I know that the "W" antenna placement criteria are pretty strict. I'm curious if anyone has flown a significant number of hours with the "W" antenna under the cowl, or of they have found another location that has given solid results.

Pictures, of course, are always good....

Paul
 
Paul
Mine is placed under the cowl and I have two years and two hundred hours with it there and reception has been excellent. It is close to the firewall and a bit off centre to the left.
 
Mine is installed in my wing tip with solid result. My understanding of the "W" antenna installation is that you need a minimum of 13' and no longer then 26' of cable to meet the spec. I was also advised of avoiding under the cowl due to heat but I know many have installed them with no issues.
 
Bavafa said:
...My understanding of the "W" antenna installation is that you need a minimum of 13' and no longer then 26' of cable to meet the spec. I was also advised of avoiding under the cowl due to heat but I know many have installed them with no issues.
Click to expand...

Is that 13 foot requirement just for the W antenna? I just moved my "classic" 430 antenna out from under the cowl in favor of the glare shield on the -8, and that results in a 13 inch cable.
 
Toobuilder said:
Is that 13 foot requirement just for the W antenna? I just moved my "classic" 430 antenna out from under the cowl in favor of the glare shield on the -8, and that results in a 13 inch cable.
Click to expand...
Minimum of 13' of cable is for the WAAS model and shorter cable does not mean it will not work, only that is not guaranteed and it will not meet Garmin specification.
 
My installation manual says something to the effect: The antenna
MUST be located on the top of the aircraft. Typically, the best location is centerline as high and far forward as possible, just aft the windscreen.

Our company aircraft have the antennas installed in this manner. We have had no issues of loosing the WAAS nav solution. I installed the WAAS antenna on my RV9 just aft of the canopy slide. Have had no issues of loosing the WAAS nav solution.

The WAAS uses satellites down to a 5 degree mask angle elevation, so an unobstructed view of the sky is required. Personal experience from WAAS avionics testing has verified that airframe shielding of the WAAS antenna can cause WAAS approach guidance to flag off.
 
430 waas

Hi Paul,
Met you at L.O.E. last year. My 530 waas antenna is under the cowling and works great. No issues unless I go upside down :eek:, it just takes a few seconds to find the satellites again. I would recommend you make the bracket long enough to mount the antenna foreward an inch or so in front of the top 90 degree lip of the firewall (for best unobstructed view in any azmuth). Waas is so cool - 200 and 1/2 from satellites! :cool:
 
WAAS

Paul,

I recently learned the hard way that the antenna must be a minimum of 18" from my AFS system or RF will cause problems with satelite reception. The 13 foot minumum cable is also required. I have my antenna mounted on the glareshield and will soon move it forward under the cowling to eliminate the RF problem. What I need is a dead antenna that I can mount in the glareshield to cover the scare moving it will leave in my nice leather glare shield cover.

Pat
 
Thanks for all the input folks! Yes, i am aware of the cable length issues - I figure a short coil of wire between the stack and the antenna will be OK if I go back under the cowl - I'm also not worried about the heat aspect (like I said, my "non-WAAS" has been there for five years and close to 1300 hours...). I was mostly looking for folks that have flown it in various spots on the -8 with good results,and it sounds like there are a number. For those not familiar with the -8, there is simply no good place in the back, other than UNDER the canopy (and even that can be blocked by the canopy frame), since the canopy slides all the way back to the empennage fairing.

Paul
 
Under the cowl works great

Easy to make a plate that is held to the top of engine mount using adel clamps and then just attach the antenna to the plate. Works great for my with my 430W. Very simple and clean to do it this way. I was skeptical but at the recommendation of others went this way and highly recommend it.
Tim
 
Redwagon said:
Easy to make a plate that is held to the top of engine mount using adel clamps and then just attach the antenna to the plate. Works great for my with my 430W. Very simple and clean to do it this way. I was skeptical but at the recommendation of others went this way and highly recommend it.
Tim
Click to expand...

This is what I did and I like it, too. One end attaches to the firewall (I used a hinge) and the other is attached to the engine mount with an adel clamp. I was also able to place the hockey puck backup GPS on the same plate.
 
430 WAAS antenna mount

Hello, Paul,

I have the WAAS antenna mounted on the glare shield slightly to the right of the C/L, and have had no problems with RF interference or drop out of the signal. Glideslope and azmuth both work great on RNAV approaches. I now have about 63 hours on the system. My 430 drops out if I go inverted, too, but I hope not to do that on the approach. Somehow I missed the 13' antenna cable requirement; mine is about 18" long and I have had no problems. The only problem that I have found is that there is some glare off the antenna itself when flying up-sun. Cured nicely by a piece of black cloth over the antenna when it is bothersome.

On the antenna length: does anyone know what benefit would be achieved with the 13 foot cable (besides a big coil of cable windng around behind the panel)?

Craig
 
Possible answer.

(Garmin manual 190-00357-02 section 3.10.1) The original Garmin 400/500 installation manual simply stated that the GPS antenna coax had to be 50 ohm coax and could not be have more than 10db of signal loss at 1500 mhz.

The new 400/500 WAAS equipment is very sensitive to the exact amount attenuation between the GPS antenna and the panel mount 400/500 receiver, and the type of shielding on the coax. The new 400/500 WAAS install manual states that the GPS antenna coax cable loss, including connectors, shall be between 3db and 7db at 1500 MHz in order to maintain proper rejection to interference signals.

Also the coax must have two shields (i.e. RG-58 coax is not acceptable). If the measured loss is less then 3db, extra coax or an external attenuator will need to be installed to bring the attenuation up to 3 db.
 
gear1 said:
Hello, Paul,

I have the WAAS antenna mounted on the glare shield slightly to the right of the C/L, and have had no problems with RF interference or drop out of the signal. Glideslope and azmuth both work great on RNAV approaches. I now have about 63 hours on the system. My 430 drops out if I go inverted, too, but I hope not to do that on the approach. Somehow I missed the 13' antenna cable requirement; mine is about 18" long and I have had no problems. The only problem that I have found is that there is some glare off the antenna itself when flying up-sun. Cured nicely by a piece of black cloth over the antenna when it is bothersome.

On the antenna length: does anyone know what benefit would be achieved with the 13 foot cable (besides a big coil of cable windng around behind the panel)?

Craig
Click to expand...

Craig,

Do you have any glass such as AFS that produces an RF signal? Just curious, I have not moved my antenna yet but I have been told that the RF issue has been verified.

Pat
 
Mine is on top of the dash and I do have GPS signal loss. I dont know at this point if it is due to antenna placement or connections.
 
Antenna RF interference

Pat,

Equipment that I have:

GNS 430W
Garmin SL 40 Comm 2
Garmin GTX 327 transponder
Garmin 240 Audio Panel
Dynon HS 34 HSI controller
Dynon FD 180 EFIS/EMS/Autopilot with Dynon servos
Dynon D10A (Standby EFIS and engine instruments)
GPS 396 with GXM 30 XM antenna and standard GPS antenna on glareshield

So far, I cannot identify any RF interference, have had no RAIM warnings and no WAAS warnings yet. It appears that I should check the attenuation, though.

One thing that I had not thought of: does the GXM 30 transmit back to the XM Satellite? The GXM antenna is adjacent to the GNS 430W antenna, but I have had no apparent interference. Something to think about, though.

Craig
 
This thread is continuing to collect good dat afor everyone! BTW, my under-cowl mount is simply cantilevered off the firewall, and has worked just fine up to this point structurally (as well as electrnically). I am think that I will simply put the WAAS antenna in the same spot for now, and see how it does.

gear1 said:
One thing that I had not thought of: does the GXM 30 transmit back to the XM Satellite? The GXM antenna is adjacent to the GNS 430W antenna, but I have had no apparent interference. Something to think about, though.
Click to expand...

Nope - it is a receiver only as I understand it.

Oh - I can comfirm what "LAMPSGuy" found in the manual about the WAAS reciever wanting both a maximum AND a MINIMUM attenuation in the cable - hence, the minimum cable length. When I say "confirm", I mean that I was told that by a Garmin engineer as well.

Hey, I'm an Aero engineer - It's all FM to me..... :)

Paul
 
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