ktbr wrote:

Sounds like the antenna or the coax.

Good point. An overy bent or kinked and pinched coax mould be a problem.

An easy way to test this would be to swap the coax between
the two radios and see if the 430 improves and/or the 155
degrades.

Just as another data point, we had the same problem with our GNS480. The comm
section may be the same as the 430, I'm not sure about that. Anyway, we swapped
the antenna cables between the 480 and the KX155 to see whether the problem
stayed with the radio, or moved with the antenna. Oddly, the problem just went
away, or at least became less pronounced. Maybe something got unkinked, I don't
know. The KX155 is still the more sensitive receiver.

DGB