The pattern you are using,

while (my ($fileh, $repoch) = each(%radar)){        
    if ($ltgepoch == $repoch) {
        ...    
    }
}
[download]

defies the entire purpose of using a hash. The above should be

if (exists($radar{$ltgepoch})) {
    ...
}
[download]

which means your keys and your values are backwards. Switch them around and it also solves the problem you asked about.