[TowerTalk] Transmitting cap for 6 M antenna

[Jim Miller]

I made a 6 meter antenna from 1/2 inch copper pipe. Center fed(gamma match using 12 inches of 1/4 copper tube), mostly like a letter U with the upper ends folded in towards the center but not connected or very close together.  I found I need a cap about 50 pf to get the best match.  The caps I used to find the right one were ceramic disks.  I have only used the lowest power to find the matching value.  Since caps are rated in pF and voltage and not in wattage, What values do I need to use it on my 746 (100w)?  OR what other kind of cap (and what value) can I get that would be better than the ceramic disks?  And depending on the type, how would I protect them from the weather?

I have seem matches using RG8 and tubing but don't know how to calculate the length or the shorting distance.  Would this be a possible solution?  And can someone give me starting measurements for something like this?

Newbe at antennas(and most everything else too).

Tnx es 73, de Jim KG0KP