also i was trying to buy a 200pf trimmer cap for this but it seems there aren't any.
Not as a compression trimmer but you can get a 500pF variable capacitor, but new they are not cheap.
There is this one:-
http://compare.ebay.co.uk/like/120824146657?var=lv<yp=AllFixedPriceItemTypes&var=sbar&cbt=y
But again there is this one:-
http://www.radioworld.co.uk/catalog/second_hand_520pf_medium_spaced_variable_capacitor-p-8916.html