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MMC Question



Original poster: "Willem Bosma" <wbosma-at-stud.tue.nl> 

Hi everybody,
New to the art of coiling, I am building a tabletop TC with an impregnated
cardboard secondary. Its winding length is 275 mm and the diam. is 67 mm. I
made a nice linear static gap with 10 copper tubes, l=80 mm, d=15 mm, each
gap 0.3 mm, which sparkles beautifully when connected to my 8/50 NST. The
solenoid that I made for it, D=150 mm, l=60mm, n=10, d=3mm, I plan to scrap
and make a pancake coil instead; otherwise I expect an overtight coupling. I
plan to make the pancake D1  4" and D2 8" with about 8 turns when using
about 25 nF capacity. This cap I must acquire wich brings me to my problem.
In polypropylene caps I may choose between 220 nF/1250 Volt a 2.74 Euro each
and 47 nF/2000 Volt a 2.97 Euro. They are WIMA FKP 1 caps and according to
some list "good". Economic sense tells me to buy the firstmentioned, but I
smell a rat. The pulsed current in 2 strings of series connected caps may
well be too much for the internal connections in the caps. Also the dV/dT is
lower. Can some experienced coiler give advice? I live in the Netherlands
and I do not know how to obtain "942" 's. These seem to be tops. Philips
stopped producing PP caps. The production is taken over by BCC.
Thomson-LCC is taken over by AVX (=>Kyocera). Is it necessary to become a
member of the Geek group for obtaining these caps? I am a pensioned
mechanical engineer and also a radio amateur (PA0TW).
Best regards,
Willem