First, you need to be working in Square pixels or turn pixel aspect ratio correction on. Personally I would work in Square pixels using the PAL DV widescreen square pixel preset. When you are finished with that render a square it's so final and check your work. The reason you want to do that is that is the only way, I repeat, the only way you will be sure that you are previewing your project the way it will appear when it is delivered.
When your project is correct then you can either drop your digital intermediate in the Adobe media encoder and use the PAL broadcast widescreen present or use your square pixel nomp in the Adobe media composer and render to the same preset, or set up a widescreen comp and nest your square pixel comp there for render. If your final video is going to be shown on the Internet you must have a square pixel copy of it anyway. No way around that.
I agree with Rick, render out a square pixel comp then use media encoder to render the final broadcast version... I ran into problems like this in the past but think it's better to create all After Effects projects in full HD compositions then just drop the final render 'master' HD file into media encoder and create whatever other versions you need... this way if the client asks for a web version as well then you already have the HD files ready to go.
Thank you very much for quick response. I will try to make square pixal PAL DV composition and render from that. But when i moved all layers to the new (square) comp every layer is in another position So I must adjust the layers. But I will try it. I am angry for myself because I always do it like you sudgest - make 1080p comp > whole video spot create in this comp > render to HQ H264 (25Mbps) > render from this file the PAL DV smaller file. But for this spot I chose to create PAL DV comp to save process time Bad decision!
Anyway I made second clip which is originaly created in 1080p composition. So I render this to 1080p H264 and then from this file to the PAL DV via Media Endcoder. And the result is confusing ONLY on the red panel is completely same "effect" like on the text from first video! But the grey panel is very nice and clean. So is the problem with deformation somehow fix to the red colour? And with thee second clip I process exactly like you sad. 1080p square comp > render to best quality 1080p H264 > render from this file to PAL DV widescreen. What I am doing wrong? Sorry for my english.
Here is the screens from MPC HC:
Red panel is wrong
Yellow is ok
HQ H264 file