Transformer Fun

The next step is to rewind the primary of the power transformer to convert the radio from 6 volt to 12 volt. First some pictures of the state of the chassis..

Disconnect the transformer wires to remove it...

Transformer out of chassis.

Remove the rivets holding it all together.

Starting to remove the "Es" and "Is".

Es and Is removed. Note all the rust.

Removing the connecting wires.

Transformer core ready for the primary wire removal. But, first there is something odd here...

The primary winding appears to have two windings. Is this because it can be connected up as a 6 volt or a 12 volt? Some research is in order. I measured the wire to be 0.028", that equates to around 21 AWG with an area of 0.41 sq. mm. Double that up and you get 18 AWG with a sq. mm area of 0.823.

Thinking this may be the way to go...

Decided to connects lead wires to each lead so that the transformer can be configured for 6 volt or 12 volt.

Here are all the E's and I's after removing the rust chemically. My plan is to go over them with steel wool and then retreat them with an iron oxide chemical.

Decided to assemble the transformer and do some transfer testing. Without doing a bunch of fancy math to determine the exact transfer because I don't know the exact turns ratio I ballparked it. I hooked up my signal generator to the secondary and measured the voltage via a scope on the primary. The relative difference between the 12 volt and 6 volt configuration should be 1/2 which it was. The ballpark transfer should be 6 volts to 250 volts, primary to secondary. 250 / 6 = 41. On the scope I had to reduce the voltage scale by 10 and divide by 4. Close enough...

I the process, I updated the leads to colors...

Completed power transformer