The first audio transformer on my AK55 early has one side open. Depotting shows internal break,no fix. This drives the screens on a pair of 45 push pull output tubes. I dont think a PT156 transformer has a center tapped secondary. What would be the right transformer for this radio. looks like the riders schematic shows 1k:7K Ct.
Also, what woud be the right audio output transformer
to use (for future reference). Thanks

Hi Doyle

The PT156 will work. Notice in the AES catalog it says push-pull grids.

Norm

: The first audio transformer on my AK55 early has one side open. Depotting shows internal break,no fix. This drives the screens on a pair of 45 push pull output tubes. I dont think a PT156 transformer has a center tapped secondary. What would be the right transformer for this radio. looks like the riders schematic shows 1k:7K Ct.
: Also, what woud be the right audio output transformer
: to use (for future reference). Thanks

Thanks Norm

: The PT156 will work. Notice in the AES catalog it says push-pull grids.

: Norm
Thanks Norm

Thanks Norm

: The PT156 will work. Notice in the AES catalog it says push-pull grids.

Sorry no message in the last followup.
Here it is:
Should this be a drop in replacemant or shoud I reduce
the 30K 1st AF filter to 20K as the Primary is now
10k where the original primary was 1.1k

The transformer is a drop in replacement. No changes need to be made. The Rider 1.1K is a DC resistance. The 10K number in the AES catalog is impedance. You will find the DC resistance of the AES transformer to be closer to 500 ohms. Regardless of how the transformer is rated it will work in your AK 55.

Norm

: Thanks Norm

: : The PT156 will work. Notice in the AES catalog it says push-pull grids.

: Sorry no message in the last followup.
: Here it is:
: Should this be a drop in replacemant or shoud I reduce
: the 30K 1st AF filter to 20K as the Primary is now
: 10k where the original primary was 1.1k