[Elecraft] Good length for portable antenna

[Victor Rosenthal 4X6GP]

I'm taking my K2/10 to a school on Wednesday to do a demonstration. I 
have a 10m fiberglass pole, and my plan is to hook a wire to it and 
either lean it against something or bungee-cord tie it to a bike rack or 
whatever is there. I will deploy a counterpoise wire on the ground.
Given that it is the middle of the day, I will probably try 20 or 17m, 
or maybe 15 if it sounds good.

My question is: what is a good length for the wire that will slope from 
the pole to my K2, and what is a good length for the counterpoise? The 
K2 has the internal tuner of course. The pole doesn't have to be fully 
extended.

I intend to say "imagine that there is an earthquake and we are cut off, 
phones don't work, etc. Watch how quickly I expand this pole and get on 
the air (etc.)"
-- 
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/