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philips: D57 (D 57 AU); Aachen Super

Martin Renz Ernst Erb Vincent de Franco Martin Bösch Mark Hippenstiel Bernhard Nagel Dietmar Rudolph Otmar Jung Heribert Jung Eilert Menke 
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Forum » Radios and other type of sets (Physics) etc. » MODELS DISPLAYED » philips: D57 (D 57 AU); Aachen Super
Gary Tempest
GB  Articles: 54
Pict.: 64
15.Nov.14 18:10

Count of Thanks: 4
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Firstly, my thanks to the poster of the information on this model.

My question is the IF frequency is given as "468 KHz (bzw 472 KHz".

Goggle Tranlator gives "bzw" as "or".

If this is correct how is the correct frequency to use determined?

thank you Gary

Dietmar Rudolph
Dietmar Rudolph
D  Articles: 2465
Schem.: 957
Pict.: 475
16.Nov.14 16:21

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The reason for using different IF frequencies was the interference produced by the powerful Luxemburg MW station, working on 232kHz, later on 234kHz. (Look here for an explanation in German.) Nonlinearities of the mixer then produced the frequency of 464kHz (resp. 468kHz). However 464kHz lies inside the bandwidth of an 468kHz IF filter, and a 4kHz whistle will result behind the demodulator.

This problen existed in the western part of Germany. Therefore, in this region an IF frequency of 473kHz was used, wheras in the rest of the "Reich" 468kHz was usual.

If you want to align your set, simply look for maximum of IF filters, may be 468kHz or 473kHz.