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Radiola 18 Amplifier & PS
#18

Thank you for the information, it all helps, although understanding some of it takes time. One reason for doing the PS and audio units is to learn about the electronics, and I am learning, but slowly.

I have both units soldered with the exception of the Hammond replacement transformer center taps on the 700 Volt coil and the 2.25V coil. The original RCA schematic indicates the 700 V coil CT is connected to ground. I assume this would be the chassis ground, but as it is 700V it seems like something to be very certain of. Perhaps someone can confirm this connection to chassis ground?

The Hammond replacement transformer also has a center tap wire for the 2.25V winding, I won't be using this winding as the #26 and #71A tube filaments are 1.5V and 5V respectively, however, I also need to do something with the 2.25V CT wire end, perhaps it should also be connected to the chassis ground?
I've soldered the 2.25V wires to the terminal strip, although these are superfluous given a 2.5V filament voltage is required rather than 2.25V.

Regarding the audio unit filament voltages, I have two new adjustable 0-30V 10 Ampere DC power supplies which I intend to use for the #26 and #71A filament voltages. This seems like a simple solution to having only the 5V filament transformer winding in the Hammond transformer that connects to the #80 filament. Although an expensive solution, these 2 PS units will also be useful in a motion control project I have underway.

Once the soldering/assembly is complete, I plan to use a Variac to slowly power the connected PS and audio units up without the tubes initially. If nothing seems wrong I can then disconnect the 120 VAC, install the tubes, power the units up slowly again using the Variac, and check the 145 voltage at the #7 terminal strip connection, and the 165 voltage at the #8 terminal strip connection.

I assume I should connect a speaker/load across the output before turning any of it on and have a 2K & 4K Ohm primary with an 8 Ohm secondary to connect between the output and speaker. I also have an old CD player to use for input via the RCA jack. Hopefully the CD output voltage will be adequate for the input on the #26 tube. 

Thank you for the assistance.


Messages In This Thread
Radiola 18 Amplifier & PS - by TN Allen - 12-11-2022, 12:09 PM
RE: Radiola 18 Amplifier & PS - by Arran - 12-15-2022, 01:14 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 12-15-2022, 10:24 AM
RE: Radiola 18 Amplifier & PS - by Radioroslyn - 12-15-2022, 12:20 PM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 12-19-2022, 06:45 PM
RE: Radiola 18 Amplifier & PS - by TN Allen - 12-21-2022, 10:12 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 12-21-2022, 10:38 AM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 12-22-2022, 05:26 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-12-2024, 11:07 AM
RE: Radiola 18 Amplifier & PS - by Chas - 10-12-2024, 02:18 PM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 10-12-2024, 03:05 PM
RE: Radiola 18 Amplifier & PS - by Chas - 10-12-2024, 08:57 PM
RE: Radiola 18 Amplifier & PS - by Arran - 10-13-2024, 03:15 PM
RE: Radiola 18 Amplifier & PS - by morzh - 10-13-2024, 08:48 PM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 10-13-2024, 09:07 PM
RE: Radiola 18 Amplifier & PS - by Radioroslyn - 10-13-2024, 10:45 PM
RE: Radiola 18 Amplifier & PS - by morzh - 10-13-2024, 11:03 PM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-19-2024, 10:42 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-19-2024, 11:24 AM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 10-19-2024, 08:33 PM
RE: Radiola 18 Amplifier & PS - by Chas - 10-20-2024, 07:15 PM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-21-2024, 10:42 AM
RE: Radiola 18 Amplifier & PS - by Chas - 10-21-2024, 11:18 AM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 10-22-2024, 09:52 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-23-2024, 09:58 AM
RE: Radiola 18 Amplifier & PS - by Chas - 10-23-2024, 10:15 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-25-2024, 06:56 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-25-2024, 04:57 PM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-26-2024, 08:07 AM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-26-2024, 05:58 PM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 10-26-2024, 07:24 PM
RE: Radiola 18 Amplifier & PS - by Chas - 10-26-2024, 08:07 PM
RE: Radiola 18 Amplifier & PS - by TN Allen - 10-27-2024, 05:48 PM
RE: Radiola 18 Amplifier & PS - by MrFixr55 - 11-30-2024, 10:32 AM



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