UY42 was first developped for 110 volt radiosets. It had a lower internal resistance, giving better preformance on 110 volt mains.
UY41 was intended for 250 volts. Since 1954 production of UY42 stopped. Afterwards UY42 and 41 are the same
Soundman2

The 40-series Rimlock tubes have a glass notch on the side which is a bit vulnerable. A metal clip or ridge is usually positioned over the notch to keep the tube in place. When inserting and removing such a tube, care must be taken that the clip doesn't damage the notch. Gently wiggle and pull until the clip slides over the notch. Nothing has to be removed.

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Hi. I managed to find that the metal skirting around the UY41/42 tube base was a bit loose, so it has now been sorted out.
One thing that I wanted to find out is that the radio tuning knob has no pointer/cursor, just a magnified portion of the dial. Was there ever a scale pointer on these, or do you work it in relation to the inner knob (has figures, 0 10,20,30 around it)? At maximum tuning capacitance, is the 0 on the middle knob set at the 190 kHz marking on the actual scale?
Many thanks
Mike

Hi. I managed to get some life from this radio, but only short lived. The fuse in the power supply blew, is this rated at 315 mA ? The details in the schematic for the Philips B3x90u are a bit vague.
I believe that the special resistor marked as N.T.C that by passes the scale lamp could be faulty, and the scale lamp itself has blown (marked as 8009 on the manual). Is this actually rated as 6.3V @
0.25 A? I used to have a cross reference for scale lamps used in Philips radios, can anyone enlighten me on this data please?
Using my previous knowledge on radios that employed N.T.C resistors (we know them as Brimistors in the U.K), I have a Ferguson radio that had two CZ type N.T.C resistors in circuit (no longer available in the U.K), and both these went faulty, causing scale lamps to blow (8 Volts @ 0.15 Amps - very rare). I eventually obtained the special resistors from the U.S.A and replacement bulbs.
What type of N.T.C resistor is used in the B3X90U radio, as there is not much information on it, and what is the wattage rating for the ballast resistor marked as 950 ohms, please?
Kind regards
Mike

Hi. Just something that I wanted to ask, was there a pointer on the tuning knob for this radio, or do they fall off? All I can see is that there is a magnifying lens on the large knob, and a calibration scale on the smaller one.
Regards
Mike