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AF3 (AF3)

Jacob Roschy Martin Renz Ernst Erb Bernhard Nagel Eilert Menke 
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Forum » Valves / tubes - Semiconductors » VALVES/TUBES / SEMICONDUCTORS in RADIOMUSEUM » AF3 (AF3)
Philip O'Shields
USA  Articles: 3
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24.Aug.09 01:12

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

Jacob Roschy
Jacob Roschy
D  Articles: 1742
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24.Aug.09 15:06

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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 .