The two Precise audio transformers in my '20s battery TRF are open. I obtained modern replacement coils (AES PT-431, stamped A53C on the coil) and have managed to isert all but the last two metal leaves into the new coil.

I am uncertain what the electrical connections should be. The original transformer is labelled B+ , P on one side, F,G on the other. The coil has a blue and a red primary lead, two green secondary leads with a black center tap. I have connected the blue lead to B+ terminal, the red lead to P, and don't know whether it matters which green lead goes where for the secondary connections. I have not used the black center tap lead. A slip of paper with a circuit diagram of the coil shows a block-like symbol next to the blue lead, and next to the diametrically opposite green lead. The meaning of this is not clear to me.

Any advice would be appreciated.

Thanks

Lode Swinnen
lswinnen@aol.com

Hi Lode

The AES replacement was made with blue for plate, red for B+. The two green wires were for push-pull grids and the black, center tap, often ground.

You will find it doesn't matter how you wire the transformer. The red & blue are primary. One to B+ and the other plate. For the greatest gain one green should go to grid and the other to filament, ground. Do not use the black.

You can reduce the gain by using one green and the black wire, leaving a green disconnected.

Leaving out two metal leaves will reduce low frequency responce slightly. You would need a signal generator and scope to see any difference.

Norm

: The two Precise audio transformers in my '20s battery TRF are open. I obtained modern replacement coils (AES PT-431, stamped A53C on the coil) and have managed to isert all but the last two metal leaves into the new coil.

: I am uncertain what the electrical connections should be. The original transformer is labelled B+ , P on one side, F,G on the other. The coil has a blue and a red primary lead, two green secondary leads with a black center tap. I have connected the blue lead to B+ terminal, the red lead to P, and don't know whether it matters which green lead goes where for the secondary connections. I have not used the black center tap lead. A slip of paper with a circuit diagram of the coil shows a block-like symbol next to the blue lead, and next to the diametrically opposite green lead. The meaning of this is not clear to me.

: Any advice would be appreciated.

: Thanks

: Lode Swinnen
: lswinnen@aol.com