Antique radios, Old Time Radios

AF3 (AF3)

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Forum » Valves / tubes - Semiconductors » VALVES AND TUBES in RADIOMUSEUM » AF3 (AF3) To the tube

Philip O'Shields

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24.Aug.09 01:12

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? AF3 (AF3)

What can I use as a more modern equivalent to a AF3?

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Jacob Roschy

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24.Aug.09 15:06

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6K7 or 78

Hi Philip,

there is no direct modern equivalent, the AF3 was the end of the line.

However, you can use a 6K7 (-G, -GT) as substitute, by changing the socket and supply the 6.3 V heater voltage, probably by a small 4 to 6.3 V step-up auto-transformer or by some additional windings on the power transformer. As well you need to realign the surrounding tuned circuits.

A 78 may also work.

Best Regards, Jacob

This article was edited 24.Aug.09 15:08 by Jacob Roschy .

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