[mickey1]

Audio output transformer has open primary. output tube is a 42 and schematic about 3 watts+/- of power. any suggestions as to what I need to replace the transformer :

[Arran]

Pretty much any output transformer used with a another 42, a 6F6, 6V6,or even a 6BQ5 will work as a replacement, there are others of course but the plate impedance is pretty close between those tubes.
Regards
Arran

[mickey1]

thank you for advise--will do.

[Radioroslyn]

Or if you want to live life on the edge you can use a 6.3v filament transformer. the 110v side goes to the plate circuit and the 6v side to the speaker.
Terry

[codefox1]

Agree with all, you'll get some audio if everything else is OK. Then you can fine tune it and get a proper transformer