The Torn.Fu.d2a was a simplified version of the Torn.Fu.d2 made in the final months of the war. To simplify production the "Rasten" (frequency pre-select) were omitted, the frequency calibration ports were changed, the antenna current meter was replaced with a lamp type indicator. I haven't studied the internals of a d2a, but it is likely that there may have been some production simplifications there too. As far as I am aware, frequency, performance etc. remained the same as with the d2.