Well, I finally got it done. It’s a 12" Faraday Enclosed Type, original movement, solid brass gong, patented 1907. It took a few weeks of part time tinkering to get it cleaned up and working. I made the new coil cover using 1/8" R/C aircraft grade birch plywood. This cover replaces the OEM cover and screws directly into the threaded holes on the bell frame.
I know this bell is too big, but it was the right price with the right “look”, so I ran with it.
The 315 Mhz receiver is mounted to the inside of the coil cover using a “pillow” of RTV silicone adhesive.
The metal face cover had to be omitted due to interference with the radio signal.
Bell pics: GB Firehouse Bell | Flickr
I then began assembling the button using a Square-D 9001 TR-55 button with the half guard. After carefully removing the half guard it was mounted to a Grant #5894 Signature series automotive horn button. I machined an aluminum base plate to lock into the 3 detents on the horn button.
After purchasing the single channel 315 Mhz key fob-style Tx/Rx set on eBay, I gutted the components and mounted the Tx pcb with the button centered on the base plate. The PCB button only has about .020 travel, do I fabricated a light spring loaded device to absorb any excess travel from the Square-D button and prevent damage to the pcb. There is also a layer of 1/8" silicone foam rubber under the pcb to support it.
The 9.37" antenna wire had to be routed outside the horn cover to maximize the transmission range, but it’s a pretty small coil and not noticeable is you keep around the back.
Once the components were in place, I snapped the pushbutton / horn cover assembly onto the base plate.
Button pics: Janine's Button | Flickr
And waddayaknow - it WORKS !