Of all the transformers I’ve worked with the LW seems to be a bit odd when phasing with modern transformers or using to operate modern equipment. When properly phased with a modern CW and used with a Williams sound board (U to center rail and A to outer rail) - it puts the WHISTLE button the ‘bell’ side. No problem for PW equipment equipped with a whistle tender. But with a modern unit equipped with a modern whistle tender - it doesn’t work. And if it happens to have a ‘bell’ - the whistle button activates that.
In looking at the rectifier circuit - I’m wondering if it’s possible to somehow ‘reverse’ the wiring and make the whistle button work with modern whistles when it’s phased with a modern transformer?
If you’re not using the B and C fixed voltages, you can just swap A and U to reverse the whistle-bell polarity. This will also reverse the phase of the AC voltage out; but you can cancel that by reversing the line cord.
If you want to retain A as the common, you should be able to swap the two wires to the rectifier. One should be red, from the transformer. The other should connect the rectifier to another point on the whistle-control switch. I would avoid disturbing the copper-oxide rectifier. Instead, cut its two wires and reconnect them swapped.
FYI - project was successful, I reversed the disc and it seems to work just fine w/ common grounds as labeled while phased w/ modern and other PW transformers and it triggers the whistle on modern equip (not the bell) - thanks