>use a linq join

I am having problem trying to implement a join solution. Here is my last attempt (this one doesn't compile):

public override SChannels GetById(object id)
        {
            //var sChannel = _siriusContext.SChannels.Include("ScsgLink")         

            // .Where(x => x.ChannelId == (Int32)id)
            // .First();

            //foreach(ScsgLink link in sChannel.ScsgLink)
            //{
            //    link.GroupDescription = _siriusContext.SpGroup.Where(sp => sp.GroupNo == link.GroupNo).FirstOrDefault().Descrip.Trim();
            //}

            var sChannel = base.GetById(id);

            var query = from links in _siriusContext.ScsgLink
  join groups in _siriusContext.SpGroup
      on links.GroupNo equals groups.GroupNo
                        where links.ChannelId == (Int32)id
  select new { ChannelId = links.ChannelId, GroupNo = links.GroupNo, ExpireHrs = links.ExpireHrs, Percentage = links.Percentage, GroupDescription = groups.Descrip.Trim()   };

            sChannel.ScsgLink = (ScsgLink) (query).ToList();
            return sChannel;
        }

The commented code works, but it's not efficient. The uncommented code doesn't work when I try to put ScsgLink in front of the new operator giving me an error in run-time:

System.NotSupportedException was unhandled by user code
HResult=-2146233067
Message=The entity or complex type 'Siriusware.Data.ScsgLink' cannot be constructed in a LINQ to Entities query.

---------------------
UPDATE. Loop works, I haven't yet checked the query behind, though:

 var query = from links in _siriusContext.ScsgLink
  join groups in _siriusContext.SpGroup
      on links.GroupNo equals groups.GroupNo
                        where links.ChannelId == (Int32)id
  select new {
      ScsgLinkId = links.ScsgLinkId,

      ChannelId = links.ChannelId,
                
      GroupNo = links.GroupNo, ExpireHrs = links.ExpireHrs, Percentage = links.Percentage, GroupDescription = groups.Descrip.Trim()   };

            sChannel.ScsgLink = new List<ScsgLink>();
            foreach(var link in query)
            {
                sChannel.ScsgLink.Add(new ScsgLink {
                    ScsgLinkId = link.ScsgLinkId,
                    ChannelId = link.ChannelId, GroupNo = link.GroupNo,
                    ExpireHrs = link.ExpireHrs,
                    Percentage = link.Percentage,
                    GroupDescription = link.GroupDescription
                } );            }
            return sChannel;

Also, I didn't re-try the using ScgsLink in front of the new yet, but in my original try I forgot to add PK in the list of columns. In this code I use PK in both places.