philips: AM2 versus EM4 question

When I bought my Philips D58AU, it arrived with an EM4 instead of the AM2 and two 1M resistors in the base.  I have looked everywhere online and cannot see that the EM4 is a substitution.  I'm hoping someone can shed some light here.

Thank you,

Donald

To thank the Author because you find the post helpful or well done.

Dear Donald,

The AM2 was a Telefunken tube. Philips and Telefunken were strong competitors in those days. So when Philips developed the EM4 in 1939 they probably changed from the competitors tube to their own EM4. The radio had a mixture 4V and 6,4V tubes anyway, so the different heater voltage was not a problem.

Regards,

Rolf

To thank the Author because you find the post helpful or well done.

So even though the tube diagram in the radio says AM2, the EM4 might be original?

Thank you so much for your answer.

Donald

To thank the Author because you find the post helpful or well done.

Dear Donald,

May be the wiring of the heater cables will tell you if this is original or done later. The reason why I think it could be original is the situation at the time the radio was build. This was just the period of the beginning WW II. in those days all radio producers were forced to stop the radio production and produce military equipment for the army. In that time many exception from the role were possible.

Regards

Rolf

To thank the Author because you find the post helpful or well done.

Herr Beckers,

You were correct.  I found the filament wires were moved and you can see fresher solder.  Also, there are now two 1M resistors on the socket base.  Many many thanks for your help.

Donald  

To thank the Author because you find the post helpful or well done.