The DX 100U was the international version of the DX 100B.

The main difference with its cousin for the American market was that the mains transformer was designed for European voltages.

Other differences include simplified crystal facility (only one position), a different pattern in the two-tone paint of the front panel, and a different tube complement : 6CH6 tubes are used instead of 12BY7 and KT88 tubes (the British version of the 6CA7) replace the 1625 tubes in the modulator.

Another major difference was the presence on the rear apron of a toggle switch used to reduce the PA input to 10 watts, in order to comply with British regulations of the time for 160 metres. I do not have a schematic diagramm for the modification, but it mainly consisted in reducing the drive and the high voltage of the final. 

The files :

DX100U.jpg : photo of the front panel

DX100U_1.gif : block schematic

DX100U_2.gif : schematic diagramm

DX100U_3.gif : table of values

DX100U_4.gif : base connections of valves.

The jpg file shows the front panel of a DX100U I recently acquired in an auction sale in Ireland.

The gif files contain documents found in The Short Wave Magazine, March 1960.

Best 73

Claude EVRARD - F5HSH