radionette: incoherent socket on Folkemottager Nett2

I just got a Folkemottager Nett2 with no tube. The output pentode is supposed to be E453-6 pin, but the corresponding socket (in the middle) looks like a P8A-8pin.

I wish to know what tube could have been used in this radio.  The cabling uses 7 of the 8 contacts of the sockets.  

Any hints would be welcome.

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Hello Pierre,

there is no direct successor of the E453. As 7 contacts are wired, it's most likely the very common AL4 was used as substitute.
Note the grid bias voltages of E453 and AL4 are very different, so a bias re-matching might be necessary.

Best Regards, Jacob 

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Hello Jacob,

thank you for this information, it seems indeed a serious candidate. 

I think this socket swap has been made by the previous owner. It is fixed by means of screws (not rivets). Some capacitors seems also more recent than others. The bias could have been adapted.

Anyway I will have to draw the schematic to compare with the regular schematic and possibly confirm AL4. 

Regards

Pierre

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After checking the wiring of my radio, the cathode resistor of the output pentode is around 110 ohm which seems consistent with what is adviced for the AL4 (E453 would need 500 ohms). Jacob, I think you were right.

Pierre 

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Hello Pierre,

the choice of P8-base substitute types for the E453 is rather small, only the types AL1, AL2, AL3 and AL4 are more or less qualified.

7 wired contacts fits only to AL3 and AL4, whereby the AL3 was only short-lived and is almost identical to the AL4.

The AL2 has a top grid cap, hence without control grid at the socket, the AL1 is directly heated, hence without cathode connection on the socket.

Regards, Jacob

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