Lionel Transformers LW and TW

Thats normal...    

I agree. Don't know why they work this way but have overhauled a bunch of these and have noticed the whistle works better if the button is pushed/turned slowly down until the whistle blows.

The classic Lionel transformers and their whistle/horn activation controls have 3 positions:

Off - No whistle
Pickup- High DC offset just enough initiate the command
Hold - Minimal DC offset to hold the whistle command active and an additional +5V Boost to for older air whistles

The modern electronics generally only react to the Pickup and not the Hold position.

On the LW, the Pickup position is selected by pushing the whistle button partway, but not all the way to the stop. Turn it just shy of the Hold position (just shy of the position that provides the 5V boost that brightens the headlight and speeds the motor).

This is documented in the Lionel literature:

The reason for the resistor was to reduce the load on the rectifier. With a properly sized modern diode this is unnecessary. The resistor should be removed with a modern conversion. This then should keep the whistle working in both positions 2 and 3. 

@David Johnston, experts leave the resistor wires in when doing standard diode replacements. (https://ogrforum.com/...71#77875232795593471)

The rumors around removing the resistance wires seem to stem from experiments with using zener diodes.

Hi. Thanks for your response. I was unable to get the link to work. As far as removing the resistor, advocating using the middle, #2 position to blow the whistle, is the same as removing the resistor. If you could get the link to work, I would be interested in seeing the logic for not removing the resistor. I believe it was only the postwar Multivolt transformers that used a resistor to shunt some current around the rectifier. Several of the prewar devices just apply the half wave DC continuously.  Would like to here more on this if it does not hijack the OP’s intended question. 

Edited the reply so the link works now... Copy paste didn't copy the link, just the shorted non-functional representation the first time...

Additionally, the hold position loops in a boost voltage of 5 volts to overcome the additional draw of the whistle motor.

the schematics don't look like its shown backwards to me!