Here's is a question for you: Are you using the CM5020 just for receiving VHF channels and the DB8E just for receiving UHF channels? If so, then you could combine them using a UVSJ combiner. If not, then you might could use a custom combiner designed for your specific channels. It all depends on which specific channels you want to receive on each antenna.
There is an eBay seller jan_jenca in Slovakia who custom makes the combiners at reasonable prices. I have ordered from him and was very pleased with the product. He also has a web site.
http://www.antenne-komponenty.eu/eng...zlucovace.html