06-07-2015, 08:07 AM
Hiya Kid,
Well after consulting my 1947 RCA toob manual I find that plate load resistance for the push-pull 71A's is close the resistance the singe ended 47. Meaning that you could just rewire the xformer you've got. I won't hurt anything as the current is less with the 47 than the two 71A's. So what you would do is connect the plate of the 47 to one end of the primary and the HV to the other end. The center tap is left unused.
Terry
ps You didn't state if your xformer is good on the model 20 spkr ,I assumed that it is...
Well after consulting my 1947 RCA toob manual I find that plate load resistance for the push-pull 71A's is close the resistance the singe ended 47. Meaning that you could just rewire the xformer you've got. I won't hurt anything as the current is less with the 47 than the two 71A's. So what you would do is connect the plate of the 47 to one end of the primary and the HV to the other end. The center tap is left unused.
Terry
ps You didn't state if your xformer is good on the model 20 spkr ,I assumed that it is...
