Tony,your use of a microwave transformer for your choke,is no good.Stan used a EC52 core and wrapped it with 18 gauge wire.There was 56 turns for each choke wire,bifiller wound would work out to 14 turns per layer per wire,four layers total.The inductance was 760uH each.Each layer was seperated with a thin cardboard.Make one and try that,you should be able to get the voltage up better than you are now.
Don