[Elecraft] K-3 not keying Amplifier properly

[RLVZ at aol.com]

Hi Guys,
 
I've got a K-3 that I just connected to my Amplifier for the first  time 
and it is not keying my Ameritron AL-1500 properly.  About 50% of  the time it 
keys the amp properly so the first CW character is sent on  time but the 
other 50% of the time it keys the amplifier late and the  first CW character 
does not get transmitted.  
 
I have tried different settings of the K-3's "TX DLY" with  no improvement. 
 I am operating the K-3 in "SEMI-QSK" mode as the Amp  does not have QSK.  
The relay cable connected between the K-3  "KEY OUT" and the AL-1500 "RELAY" 
jacks.
 
My other radios key the amplifier fine everytime so this is  an issue with 
my K-3.  Are there any other K-3 settings I can  change that will correct 
this?
 
Thanks!
 
Dick- K9OM