the tv in the den is a digital and picks up 28 channels. Mine is a digital without a tuner so I have an rca converter but only get 20 channels. Both using the same house mount antenna. Is it because of the converter that I am receiving less channels than the tv without a converter?
It may be because the converter isn't as good as the tuner built into the den TV.
It may also be because the signal is weaker in that antenna connection.
To find out take the converter box to the den. Disconnect the antenna wire from the TV and connect it to the converter box.
Connect the converter box to the TV with AV cables and run the channel scan. If you only get 20 channels it's the box. If you get more than then you can use a distribution amp to boost the signal. That would install before you split the antenna wire.