Just received this email and thought it may help others

Hi Paul..
Just fitted your keyer PCB to a 901. Using a switch to bypass the tip for a standard key this letter is the answer everyone is looking for to replace their Curtis keyer on their 101's, 901's & 902's. You have created a cure without realising it. Well done. I hope you can use this simple diagram to help sell more. Kind regards, James. M1APC