Id. Junkers Ju 188 D2 Part

Hello !!
Does anyone have an idea on what this piece could be ?
It comes from a Junkers Ju 188 D2 crash site.
It's 9cm x 7cm and about 0.5cm thick.
The disc in the middle with the hole rotates, so that you can have 3 different positions/situations: closed, big hole, small hole.
On the front it says "F353" and on the side you can barely read the words "Eingang E B ??????????? gs ??? tung", that's it, unfortunately no Fl. Nr.
Thanks to everyone in advance !!

[edNorth]

I believe the key here is number "F353" where F stands for F-Anlage / Funkanlage (Radio reciever / sender equipment) and next 3xx can indicate it be part of Fu Bl., what was blind beam (landing) or navigation system by Lorenz. Reciever antenna was under rear fuselage, but was flush on Ju 188 D-2 (Recce) version.. Part 9D of Ju 188 manual likely can solve this, but I can not find it my files, not shure I got it.
Above info is deducted from Manual "Part 9B Bordnetz" for Ju 88 A-1 / A-5 version, and does not go into deep parts detail.

Experts can correct this if they so whish...

I wonder if assembly F353 contained an light bulb, flashing if an Marker on the approach system was passed.
http://www.island-images.co.uk/ATC/z...orenz-diag.jpg

-Ed

Hello Ed,
thank You very much for your help.
I always thought that for "F-Anlage" they would use the letters "Fu" (not the F only).
But I checked every manual I have anyway, also the manual for the Fu.Bl.2 (I know for sure that this exact landing system was equipped on the crashed plane) but I could not find anything like the part I posted.
I also checked every cockpit and radio panel picture I could find (Ju 88, Ju 188 and others) but nothing.
Is it possible that the manuals don't go deep into details as You said, and so this is the reason why I can t find it?
Neither have I the "Part 9D of Ju 188" and I don t know where to find it...
Thank you again

AR