Parakeets have become a real problem and attract crows and pigeons. They are also very noisy and eat all the seeds intended for smaller birds. As this is now a problem for others I wonder that a seed feeder producer hasn’t tackled this question. I have a weight closing feeder but this doesn’t stop them. I have seen suggestions of enclosing feeder in two hanging baskets but wonder if this would work.
I don't have your parakeet problem but I do have a Starling problem so bought a caged feeder to only allow the small birds in, they took their time getting used to it but many now use it and the Starlings don't even try. I know the parakeets are really resourceful but looking at my one, I don't think they'd get at it either?
They might learn to open it though
I think they may still get in the hanging basket scenario as that's what use to stop the pigeons and great Spotted Woodpeckers and Starlings can still get in so maybe best try scozmos idea of a proper made one with only small gaps in it
(Pardon the Scottish Accent)
Search guardian feeders, as per scozmos suggestion ️