I wanted to buy a finished Audio-Comm brand XLR plug with the necessary blocking capacitor to run an XLR mic with my Icom 7300, but it seems they are not allowed to ship here, via customs. The Heil ones are way too expensive. Would like to build my own. What sized blocking capacitor is necessary, and where does it go? I suppose I can just solder it on the inside of my mic (the Behringer XM8500). Thanks.