Update.....
I disconnected all the auxiliary wires from the ammeter, leaving only the wire from the regulator and the wire to the battery. Isolating the charging circuit to only the battery. And as Jon G said, the horn circuit is not fused so if there's a short in the horn cct, it may take some wiring with it.
I started the engine and still full + on the ammeter, so it had to be either the regulator or battery. Since I'm not smart enough to adjust the regulator I thought I'd check the battery more closely. Remembering Jon G's original comment: " Generally, my experience has been when this happens it's either the battery (first) or the regulator (second) " Words to live by.
I originally thought the battery was fine because it's only 6 months old and had a voltage of 12.6V and engine cranking was normal. This engine starts instantly so it doesn't put much load on the battery. I attached a battery charger to the battery and it showed a charge current of 6 amps. Goes to show, yet again, it's not always wise to check a battery with only a volt meter.
I'll take the battery to a shop tomorrow for a load and maybe buy another one. In any case, the ammeter /regulator / generator were working 'zactly as designed.
Thanks to all for your assistance to fix a problem that didn't exist.
