Blake Hawkins
From:
Florida
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Posted 26 Oct 2000 12:00 pm |
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It will fit physically and the base pin wiring diagram is the same.
However, the 5U4 requires 5 volts at 3.0 amps for the filament.
The 5AU4 requires 5 volts at 3.75 amps for it's filament
Also, the 5U4 will stand a higher peak voltage of 1550 volts vs. 1400 for the 5AU4.
So, while it would work, I wouldn't do it.
The extra filament current requirement is likely to overload the power transformer in the amp which will make it run hot and lead to premature failure.
Also, depending on how close to the maximum ratings the amp runs the tube, you could get some internal arcing in the 5AU4.
The tube ratings information come from The RCA Receiving Tube manual, RC-23.
Blake
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