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Keith,
Have you checked for interference from your com radio?
This can happen when the receiver is tuned to certain frequencies, even when not
transmitting. It will be worse when the GPS antenna is near the radio
stack.
I had to put my GPS antenna in the back to avoid
this.
The signal reception on my Garmin 420 is really dodgy. We've
tested the unit on a bench and it worked great. We've swapped the
antenna, no change. We swapped the antenna cable, it actually got quite a bit
worse (the old one had intermittent issues, the new one is dodgy, nearly full
time.)
If I route the cable 'just so', I can make it work fairly well
on the ground with the canopy open, but it tends to go to hell when I close
the canopy.
If I unscrew and lift the glare shield about 1/2" -
1", the reception is great. The GPS antenna is attached to the top of
the glare shield on the co-pilot side.
I'm going to get some help from
a shop in debugging this...but it seems to me that part of the canopy is
either causing interference within the antenna cable, or the antenna
itself.
Has anyone experienced anything like this before? This is in a
360.
Keith
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