It was a draft doc in case I ever got around to trying this out. Just a bunch of notes on VHF roofing filters, things to watch for, etc. No one else would understand the stream of consciousness writing style except me :)
Much better: read AC0C's nice presentation on roofing filters:??. He has a couple pages on VHF/upconversion architectures.
There may be unintended consequences of installing this roofing filter in the FT-980. For example, the inrad filters have a measurable insertion loss (as you'd expect from a 6-pole filter), and no onboard amp to compensate. The result is that you are depending on the AGC system to compensate for this loss by increase the gain. Since the FT-980 AGC wasn't specifically designed for this, I'm not if there are any negatives beyond the obvious.
I would love to see before/after results on certain things like receiver sensitivity, blocking, IMD3, etc. This would be a good way to tell if the mod is a net positive or no.
These are some efforts to do just this on other radios to varying degrees:
--
-Mat Breton, N8TW
Mat Breton N8TW