10-02-2021, 07:42 AM
Hi Bob,
Any output transformer from any radio of the period that uses a 2A5, 42 or 6F6 should do, as they all have the approximate load resistance, plate voltage, current, etc. as the 47. The 2A5 was the logical next step on evolution of the power pentode from the 47. Other than filament (heater) voltage and, in the case of the 6F6, pinouts, the specs are the same.
For RCA Radios for which I have Ryder Schematics that list output wattage of a single 47, 2A5, 42 or 6F6, the maximum out is 5 Watts. Typical "undistorted" Output is 2.5 watts. RCA's definition of "undistorted" at that time was 5% or less. The RCA Receiving Tube Manual lists power output for a 47 to be 2.7 Watts at 6% distortion, so a 5 Watt transformer should do.
Any output transformer from any radio of the period that uses a 2A5, 42 or 6F6 should do, as they all have the approximate load resistance, plate voltage, current, etc. as the 47. The 2A5 was the logical next step on evolution of the power pentode from the 47. Other than filament (heater) voltage and, in the case of the 6F6, pinouts, the specs are the same.
For RCA Radios for which I have Ryder Schematics that list output wattage of a single 47, 2A5, 42 or 6F6, the maximum out is 5 Watts. Typical "undistorted" Output is 2.5 watts. RCA's definition of "undistorted" at that time was 5% or less. The RCA Receiving Tube Manual lists power output for a 47 to be 2.7 Watts at 6% distortion, so a 5 Watt transformer should do.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
