You need to be a little more specific - there are two types of each Beogram!
Beogram 1800:
Type
 5213 - rare and unusual early turntable with novel lid with enclosed 
sides - a keeper though I doubt this is the one you have! Takes SP 
cartridges.
Type 5811-5 - First of the last series of radial 
Beograms. Looks impossibly slim and is very elegant. No Datalink and was
 designed really to go with non B&O systems. Tales the MMC1-5 type 
cartridge. Quite common as they were big sellers but that was because 
they were good! 
 
Beogram 3400
Type 5703 - Quite a
 rare deck - looks just like a 1900 and shares the slightly unusual 
drive mechanism of drive belt and idler wheel unlike the later simpler 
belt drive decks. It could be fitted with a CD4 decoder and if so 
fitted, this is unusual and well worth keeping. 
Type 5726 - This 
was a US only model and looked similar to the 2200 with a sloping front 
and buttons on the front. There was also a 3404 which was much the same 
but had the circuit in place so it could be operated by remote via a 
Beomaster 2400. To complicate issues still further, a later model with 
the new arm from the 1700 also existed! 
Hope that helps!