It sounds like we are taking the same path.
In the Fidelity Fixed Income, Bonds & CDs tool, if you select "Bonds" and then "All Offerings", you will arrive at a screener. In the "Show More Criteria" you can select "Yes" for "Call Protection". Under "Product Type", exclude "Corporate High Yield", "TIPs", and "Municipal". The latter two are fine but should be screened separately. For "Ratings", I like Moody's "A2 to Aaa" and for S&P I like "A to AAA". I also like to untick "Show bonds matching either ratings range" so that bonds have to be in both ranges. Set the date range. I set the Yield to worst at about 3.75. You can then run the query. Sort the results from highest yield to lowest.
The results with Yields more than 4.5% are:
Federal National Mortgage Association
Federal Home Loan
Federal Farm Credit
Bank America Corp
Hope this helps.