[Elecraft] KAT2 without balun - which doublet length is better?

[ub5_073_oleg]

Hi,

I'm going to use my K2 with KAT2 internal ATU to operate a
doublet from 80m to 10m including WARC bands without a
balun. Among others, Dave's W8FGU home page inspired me to
try this.

I hope this is not a problem, especially when battery-fed
during portable operation, as there is [almost] no
HF-connection to the ground (the whole system is 'floating')

Quick modelling of 2x20m + 13.5m feeder antenna shows that
KAT2 should be able to do the job, as its 20uH and 2400pF
are enough on all bands.

My question is: can/should I make it easier for KAT2, e.g.
choosing other antenna or feeder lentgh or maybe
adding/removing a piece of feeder on some bands? Are there
some proven length to use? 

73  Oleg