[Elecraft] Rear Panel Mic help ple

[Ed Stallman]

I' m trying to  use a Heil PR 781 microphone on the K3 rear Mic jack 
. With the settings I'm using now , I must scream into the Mic for 
radio to transmit

Here are my settings.

Main:MIC-SEL   I have set to RP, then taping the 1 sets to RPH

MIC GAIN = 60

VOX GAIN = 100

BIAS = OFF

ANTI-VOX =  0

DELAY = 5

VOX = on

Maybe the PR-781 is not a good choice or most likely I've missed a setting ?