What is PayPal's cut?
If it is more than 1.5% then I could change to a monthly check from my bank which does not charge.
Yes, PayPal charges 1.5% when donating to a charity. I can see you're in the US, here's PayPal's page about this: how much-does-paypal-cost-for-nonprofits-and-charities
Since you will be donating within the same country setting up a monthly standing order with your bank without fees does sound like a better solution. PayPal makes most sense when donating in a different currency to that of the recipient. Despite being pricy it's still cheaper than bank fees and conversion rates.