505

Dear Radio friends,

I recently received a Philips Tube, model 505.

On top of this tube is written (see pictures)

PHILIPS

CINE SONOR

505

(.33.)

Inside, one can clearly distinguish two diode systems!

I wonder if this is the same tube??

Pièces jointes

• Tube 505 (53 KB)
• Lamp 505 Philips (5) [640x480] (50 KB)
• Lamp 505 Philips (5) [640x480] (50 KB)
• Lamp 505 Philips [640x480] (46 KB)

Hello Georges,

since this tube has merely 3 pins, it can't be anything else then a half-wave rectifier, although two diode systems are visible. It's very likely that you can find a parallel connection inside the tube. I have very little doubt about the correct designation 505.

This method was even used in some other cases: have a look at the second picture of the rectifier type 1803 (under “more”) - and you can see a 1803 which is made in the same way. The connection between the two anodes is clearly visible.

Best Regards, Jacob

Thank you, Jacob.

Indeed, looking carefully into the glass base shows that the two heaters are connected in series.

But what about the other marking: CINE SONOR?

Was this rectifier used only for cinema applications? Or is there another explanation?

Best regards

Georges

Philips Eindhoven had a "Cine Sonor" department for cinema equipment production (like Siemens had a separate company "Klangfilm").

It may be that Philips tubes which are labeled "Cine Sonor" was sold for a higher price for "dedicated application", similar to the "Klangfilm" tubes which was (often) standard tubes with a different numbering system to prevent cinema operators to use cheaper tubes for replacement. As far as I know the cinema operators had to sign a contract with the cinema equipment supplier.

I do not know if those "cinema" tubes has had a higher reliability or was selected for reaching the upper limits of the specifications.

If somebody can quote a contract between cinema equipment manufacturers and cinema operators, or can provide data sheets or an advertisement folder of Philips "Cine Sonor" equipment we will know more.

Best Regards

GR