[Elecraft] KX3 and external-power

[jsodus at comcast.net]

I've completed the assembly of my KX3 and put 8 new batteries (alkaline) in it to see that it powered-up ok, which it did. 
I just felt more comfortable doing that to power-up the new unit rather than using a bench power-supply. 

I'm ready now to do the next phase "Calibration" with the KX3-Utility code. 
However, Cady's book for the KX3 suggests that the "Calibration" should be done with a stable bench power-supply. 

I wondered if I must remove the internal batteries prior to connecting up the bench power-supply. 
(I do not have the KXBC3 battery-charger option.) 
I did not find an answer in the manual or Cady's book nor did searching through the schematics yield an answer for me. 

The problem is basically academic because the batteries will be removed with virtually every intent of leaving the KX3 that way permanently. 
(Of course, that is open to change based on future experience, in which case NiMHs would be installed.) 
I have my eye on a 12V 7A SLA to supply external power when operating portable. 
A bench power-supply would be used when operating at my desk. 

TIA for any replies. 
73 Jerry KM3K