08-04-2009, 05:56 AM
I heated my latest Philco 20 filter to 200-250 for about 45 mins until the wax at the sides was bubbly, and the stuff still wouldn't come out with a pair of needle nose. I was using a foil lined stainless serving tray from a buffet table under it. That's when I decided the next time I'll support it high enough so the mess melts and falls out on it's own. I replaced those 4 caps with plastic units that'll hopefully last longer than I do. There's plenty of oil filled motor starting capacitors out there in the 1 and 2uf range that should be just what you're looking for. I used 400v caps in the filters of my first two 20s and they seem to work okay, but I haven't measured the voltage on them with the radio on. This 20 I'm using 630v caps which are about half the size of the 400s. One thing I did to keep track of which lug is which on the filter was to unsolder R15 from lug 5 of R25 and leave the other end soldered to lug 5 on the filter. That way I could clean the tar off the filter, then add labels relative to lug 5. I replaced all resistors except R8 with 2 watt units, probably overkill but there's plenty of room for them.
Dave
Dave