[Dave]

Glad the grounding did the trick for you. For future reference for all, there are limitless sources of RF interference... atmospheric & weather conditions, solar flares, computers / electronic devices, electric motors, generators, fluorescent lighting just to name a few. Back in the olden days, there weren't as many interfence causing devices in existance, and radios weren't designed with this in mind. Filter circuits weren't nearly as robust as they are these days, so the old radios are a lot more sensitive to the plight. Interference that starts in the early morning and lasts into mid-day is typically due to atmospheric conditions. Being in the two-way radio business, I get calls from customers pretty frequently, complaining about interference in the morning hours. By early afternoon it's gone. Unfortunately, there's nothing that can be done about it. It's just the nature of the beast.
Dave