I appreciate all the comments so far. They have forced me to think more deeply resulting in a partial change of mind about the meaning of a double in this position. I have been convinced by the argument that there are very few hands where a penalty double would work best. Here is one:
However this hand would have opened a strong no trump. So:
Playing weak no trump (we were not) a double is likely to be a strong no trump hand. Partner should fairly easily be able to decide whether to bid or pass.
Playing strong no trump, a double is best played for take-out. This leaves the question as to what shape and strength is necessary. Would a balanced 14 with low doubleton heart and 4234 shape fit the bill? Say:
♠AQxx,
♥xx,
♦KQ10x,
♣K10x? It was the general consensus that west would leave the double in with his actual hand and you would be very unlucky were the contract to make.
With an unbalanced hand and a heart shortage, what strength do I need to make the take-out double?
With this hand it is quite a high probability that 2
♥ doubled will make and 2
♠ is on our way. So there are some very finely balanced decisions to be made here.
Also: Quote "If you double for take out, partner will not bid 3 ♣, this would be quite silly. He will pass and collect a cold and cool top for 500." With the actual hands 2
♥ will go 2 off, which on the evening would have given you a 70% score.