Do I need an encoder for a linear stream?

Yes, you will need an encoder to send any live stream from your end such as from a camera or video source on your computer to one of your live channels inside your account.

Here are some helpful support articles related to encoder configuration and recommended encoders:
http://www.lightcast.com/user/page/encoder-configuration

https://help.lightcast.com/does-lightcast-require-or-recommend-specific-live-encoders-for-the-use-with-its-cdn

Should you need help with the configuration of your encoder, our tech support team is happy to walk through your encoder and test your live stream settings. Encoder configuration calls can be scheduled at http://techsupport.lightcast.com/

If you choose to use our 24/7 Cloud Scheduler you will not need an encoder. The Cloud Scheduler takes existing videos inside your Lightcast account and allows you to schedule them over a 24/7 time period at specific times you choose. More about the 24/7 Cloud Scheduler can be found at https://help.lightcast.com/24/7-cloud-scheduler