nobikes:
I am using the non-v ATTINY. I think switching to a 3AA 4.5 Volt supply would help then.
For the alkaline batteries I use...
3 * 1.65 = 4.95
3 * 0.80 = 2.40
Almost perfect for the 0 – 10 MHz range.
For the application you're building, I would disable the BOD.
Would there be any benefit to using a mcp1702 voltage regulator and a 9 volt battery
None that come to my mind.