AW23 Questions

[Joe Miller]

My AW23 has a transcription size phono on the top of the cabinet that has never worked even though I replaced the ceramic cartridge.  I decided to go through it to see if I could get it playing. (The radio plays fine.) As I started working on it ,I remembered that when I was in it the last time I discovered that the audio transformer between the first AF amp (6C6) and the 2AF amp (push-pull 6C6s) was open.  Someone before me had modified the first AF output to feed its plate and cathode to the grids of the push-pull grids to bypass the audio transformer. This raises several questions:

1.  I want to restore the set back to the original design.  I need a replacement audio transformer.  Anyone know where I can find one?

2.  There are at least 2 different designs for the phono input circuit on the AW23.  One version, which I think is the older version, connects the phono to the cathode of the first AF tube. This design requires the set to be detuned to a quiet frequency so that the phono audio can be clearly heard. I think this is the design I have, but given the modification that was done to bypass the audio transformer, I can no longer connect the phono input to the cathode of the AF tube. If I can find a replacement audio transformer I can connect the phono per the older design, i.e. to the cathode of the 1AF tube.

3. Alternatively (and preferred by me), the newer design shows a phono/radio switch on board the AW23 tuner chassis.  This switch not only connects the phono input to the high side of the volume control, but also changes the voltage on the screen grid of the RF and IFs to kill any RF signal from competing with the phono audio.  Anyone know where that switch is located on the AW23 tuner chassis that has it? 

Thanks,

Joe

[Joe Miller]

Upon further review, I think I have answered one of my questions.  In the set folder I see that the 7 knob version includes a radio/phono switch as one of the 7 knobs.  So, I guess my only option is to connect the phono to the cathode of the 1AF tube.  That means I definitely need to replace the audio transformer.  I don't have a parts list, anyone know what the part number is or the step up turns ratio?

[Norman S Braithwaite]

Some early version chassis were modified to the later circuit with an added DPDT switch.  I have seen this switch located on the left side of the cabinet (opposite the power switch) and on the back apron of the chassis (inconvenient, especially if the chassis is located below the phonograph).  In both cases an additional hole was drilled in the back apron.  I can understand the reluctance to modify an original early AW23 chassis to add the switch.  A UTC A-18 or A-19 is a good but somewhat pricey replacement for the original transformer.

Norman