Aaron,

The certification test requires that the GPS stay active when the microphone
is keyed on the following frequencies:

121.150
121.175
121.200
131.250
131.275
131.300

I don't know anything about an M3, but all the Garmin models have a page
that shows the satellite acquisition strength.

After you acquire the satellites, go to that page and select the above
frequencies on the KX-155. Now key the mike and transmit for about 10
seconds. The GPS is not allowed to lose it's acquisition.

If yours continues to function normally, congratulations! I've never seen a
KX-155 that will do that, with or without notch filters. In fact, King had a
white paper on the mods necessary to clean up the KX-155. The process went
far beyond adding "notch filters." Noise comes out the front, back, top and
bottom of the unit. I doubt anyone ever modified their straight 155 with
regard to King's recommendations.

Thus, the KX-155A was designed, and co-exists with GPS right out of the box.
Plus these units have many new features and design improvements.

Try the test on your ramp. Let me know!

Best,
Karl


"Aaron Coolidge" wrote in message
...
kage wrote:
: That might be true.

: But your installation will NEVER pass the required IFR certification
tests
: required buy the FAA.

: Karl

I have a pair of KX155 (not kx155a) and a Northstar M3. It passed the
interference tests as required by the FAA. I will check and see if any
notch
filters were installed, but I do not believe there are any.

--
Aaron Coolidge