Motorola Mic on a TK-690

[N3CHU]

Hi all, If I were going to put a Motorola Mic on a Kenwood what value coupling cap would I use for the best fedelity? The .0047
cap I used gives me plenty of mic gain but a bit brassy. any help appreciated. P.S. I'm getting about 7.45 volts to the mic.. 73 Davie n 3 c h u at atlanticbb dot net