Handheld problem in NORDO plane

Hey folks,

I just bought a Luscombe 8A and am launching tomorrow to fly it home.

The problem is the handheld transceiver I'm using to communicate. It
works fine on the ground. But as soon as I get 100-200 feet off the
ground it gets overwhelmed with static, like the squelch is wide open.

It's a Vertex VXA-300 attached to an external antenna.

I' ve tried turning the squelch to max. I haven't checked whether it
occurs on all frequencies because that didn't occur to me until I had
put the plane back in the hangar.

Any ideas what's going on here? All help is appreciated.

Tailwinds and blue skies,
Mike