MKG L - AKG cable for PT40

Does any one know how to make the MKG L - AKG cable, this the instrument cable for the pocket transmitters of AKG (PT40). I had made a standard Mini XRL to 1/4 jack cable but it doesn't work, when I plug it into my guitar I only get the lower frequencies and it seems like the guitar have no ground (when I move the volume potentiometer or any other switch it makes a lot of noise). Please help me, Thank you all...