Im no meteorologist so I could'nt say for sure!
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Id try and get another antenna, there only cheap and try that first. If not go down the update the firmware route.
You can run a newer version modified firmware that won't give you battery drain but without knowing what f/w your on now its hard to tell if it would make any difference.
But seeing as you have the battery drain issue (hence the inline switch) you re probably running a fairly new f/w anyway??