aviation vhf handheld radio problem

pwm wrote:
I bought a Vertex VXA-210 vhf aviation handheld and am experiencing a
strange tone when attempting to transmit with my David Clark headset
plugged into it. The tone is not present if I disconnect the mic plug
from the headset adapter. The tone also fades away if I remove the
"rubber ducky" antenna or if I cover the mid-section of the antenna with
my hand while transmitting. The radio has a feature to turn off its
built-in mic with the headset connected and I have selected it to "off",
but find it odd that when the headset mic plug is disconnected and
transmit, I can tap on the radio's mic and faintly hear the tapping
sound in my headset...

Any ideas?

Thanks,
Monty

Its RF feedback coming straight back into the headset lines.... Its
happens on mine but when i plug another aerial into the top it goes
away. You just cant use the rubber ducky aerial and headsets at the same
time you must use an external aerial. Thanks