GTN 650 spotty GPS signal

Irish_Armada

Irish_Armada

Pre-takeoff checklist
Joined
Oct 8, 2011
Messages
374
Display Name
Display name:
Irish Armada
Hey guys,

Our club purchased a Cherokee 180 recently that came with a Garmin GTN 650, which is paired to a panel mounted Garmin Aera 560. Our GPS signal is rock solid on the Aera but super spotty, at sporadic intervals, on the GTN. What are some of the common primary causes for this type of problem? I know we have trouble shot the problem a little bit to know avail so far. Our A&P guessed it's a wiring issue to the roof mounted receiver, but we aren't sure yet. Next step is to pay an avionics shop to look into it. Any other guesses of what might be causing it before we bring it in? The unit itself and the receiver both otherwise appear to be in great shape.
 
Did someone perchance paint the antenna cover to match the plane?
 
On my new 430W, it takes a while to start up (I've seen the 'position not available' warning a few times on start-up), but it goes away quickly and has been rock-solid during flight.
 
Henning said:
Did someone perchance paint the antenna cover to match the plane?
Click to expand...
Yup, this is prohibited and typically printed right on the antenna. Supposedly GPS reception is only affected by paints with metallic solids if I recall correctly.

Many in the experimental world have installed the GTN 650 GPS antenna under the cowling (roughly in the area where the air pump used to be before it was removed secondary to it being unneccessary equipment when the glass was installed in the panel). This under cowling install has worked well for us and many provided metallic paint is not or does not get applied to the cowl.
 
Henning said:
Did someone perchance paint the antenna cover to match the plane?
Click to expand...

It's not painted -- that was my first thought (and also last as I am no expert). We will look more into the cable issue.
 
How old is the unit? Could it still be under warranty? I'd look at the antenna and wiring first. :D
 
Does the aera and the 650 share the same antenna?
 
Make sure the GPS was installed per the installation manual. In many cases, a Com or ELT may need to be moved to prevent interference.


Sent from my iPad using Tapatalk
 
FORANE said:
Similar situation here:
http://www.pilotsofamerica.com/forum/showthread.php?t=72360

I would try troubleshooting it through process of elimination. Any chance you have another gps antenna available? Another RG400 cable to switch out and see if it makes a difference?
Here is the install manual for reference:
http://www.google.com/url?sa=t&rct=...dzrbfSxYeBJpzwQrQ&sig2=oQANxwqR7NuQqRYrmveyiA
Click to expand...

You forgot about RG-142B and the required amount of loss from connectors and the coax run itself.
 
You must log in or register to reply here.
Back
Top