Williams horn question

[Anonymous]

Hi All,
I've installed a Williams diesel horn board (not TBII) onto an earlier MTH DCRU reverse board. All works well until at higher speeds, the horn blips intermittently. The problem begins at 15-16 volts. It was suggested on another forum that I install a lamp in parallel but that didn't fix it. Is there some sort of filter needed? I swapped out the speakers and tried different transformers. The horn board was out of an SD-45 dummy. I know it's not the best sounding horn in the world but it would serve this engine just fine.
Any suggestions [?]

thanks,
-Mike