05-13-2022, 10:17 AM
Hi Hamilton,
You may have 2 connections reversed.
In these speakers, the field coil does double duty. It serves as the magnetic field and as a filter choke.
This is a little tricky but try this.
The point labeled 1 should be a terminal for primary lead of the output transformer. The black wire from the 6F6 Pin 3 (plate) goes here.
Terminal 3 on the speaker is a junction between the output transformer primary and the field coil. The wire that connects here should go to Pin 4 (screen grid) of the 6F6 and to a lot of B+ points in the Radio goes to this connection. This is typically also your 8uF cap (capacitor) but please trace your wires.
The last connection, #2 is the other lead of the field coil. The wire connected to this terminal should be connecting to the positive lead of the 12uF cap and also to the 5Y4 Rectifier cathode (filament) connection.
Inspect your connections at the Radio. If the Red Wire that connects to the 8uF cap also connects to pin 4 of the 6F6, the IF transformers and other points, then your connection has to be reversed with the yellow wire. If the Red wire that connects to the 8uF Cap also connects to the Rectifier cathode, then your speaker connections are good and your Cap connections are reversed.
If you got this wrong (# 2 and #3 reversed) and powered up the radio it will likely not smoke immediately, however, there will be 350V on the 6F6 plate and screen, higher voltage on the other B+ points and insufficient current through the field to develop the proper magnetism. The radio will likely hum and have low volume.
The cathode of the rectifier is usually at about +350VDC in most transformer powered radios of this vintage. This 350V connection connects to the first filter cap and to one leg of the field coil. The other leg of the field coil connects to the second filter cap, and is the source for B+ for the rest of the radio. The output transformer gets its DC B+ from this point. As the radio warms, this voltage usually stabilizes at 250VDC.
Finally, as the radio warms up, carefully inspect the 6F6. If you see a bright glow inside the tube that is not coming from the heater (filament) then shut down immediately. Your plate connection or output transformer is open and the screen is drawing so much current that it is glowing, can melt and short. This will be BAD.
Hope this helps.
Best Regards,
John "MrFixr55"
PS, Read on, I have corrected this entry after Hamilton's response, I had the numbering wrong but the concept is correct.
You may have 2 connections reversed.
In these speakers, the field coil does double duty. It serves as the magnetic field and as a filter choke.
This is a little tricky but try this.
The point labeled 1 should be a terminal for primary lead of the output transformer. The black wire from the 6F6 Pin 3 (plate) goes here.
Terminal 3 on the speaker is a junction between the output transformer primary and the field coil. The wire that connects here should go to Pin 4 (screen grid) of the 6F6 and to a lot of B+ points in the Radio goes to this connection. This is typically also your 8uF cap (capacitor) but please trace your wires.
The last connection, #2 is the other lead of the field coil. The wire connected to this terminal should be connecting to the positive lead of the 12uF cap and also to the 5Y4 Rectifier cathode (filament) connection.
Inspect your connections at the Radio. If the Red Wire that connects to the 8uF cap also connects to pin 4 of the 6F6, the IF transformers and other points, then your connection has to be reversed with the yellow wire. If the Red wire that connects to the 8uF Cap also connects to the Rectifier cathode, then your speaker connections are good and your Cap connections are reversed.
If you got this wrong (# 2 and #3 reversed) and powered up the radio it will likely not smoke immediately, however, there will be 350V on the 6F6 plate and screen, higher voltage on the other B+ points and insufficient current through the field to develop the proper magnetism. The radio will likely hum and have low volume.
The cathode of the rectifier is usually at about +350VDC in most transformer powered radios of this vintage. This 350V connection connects to the first filter cap and to one leg of the field coil. The other leg of the field coil connects to the second filter cap, and is the source for B+ for the rest of the radio. The output transformer gets its DC B+ from this point. As the radio warms, this voltage usually stabilizes at 250VDC.
Finally, as the radio warms up, carefully inspect the 6F6. If you see a bright glow inside the tube that is not coming from the heater (filament) then shut down immediately. Your plate connection or output transformer is open and the screen is drawing so much current that it is glowing, can melt and short. This will be BAD.
Hope this helps.
Best Regards,
John "MrFixr55"
PS, Read on, I have corrected this entry after Hamilton's response, I had the numbering wrong but the concept is correct.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
