PHILIPS 634A - LENTEBODE

By around 1931 most British radio manufacturers were turning their attention to the superheterodyne principle. Philips, on the
other hand, were concentrating on their 'superinductance' receivers, a superior breed of straight sets for the medium and long wave bands. 
The succes of these receivers stemmed from two specially developed components.The first was the 'superinductance' coil, which had an unusually high Q and enabled a high degree of selectivity to be obtained. The other was the ganged tuning capacitor, which had a precision hitherto unseen in such a component. This allowed two or more high-Q circuits to track accurately over a whole waveband. The coils were wound with Litz wire on glass formers and sealed inside screening cans which were up to three inches in diameter. 

The 634A has four tuned circuits and, as a result, it has an outstanding performance. It has two RF stages followed by a binode (combined diode and triode) for detection and LF  amplification. The output stage has the patented Philips pentode.