I hadn't built anything in a while. And a friend mentioned the desire to have something to check for proper deviation on various Echolink and repeater setups.
In a prior blog, Are you narrow or wide?, I covered more of the background.
There is a lot out there on this sort of thing.
FM Packet Deviation Meter
So I suggested we build this and hook it to a an old dedicated scanner. And after construction we calibrated it against a club IFR-1200 service monitor.
If you are not found of breadboarding, the above 73 article has an etched board available:
Here is a video that my friend made:
You'll be disappointed to know that Radio Shack doesn't carry the 15 vdc panel mount meter anymore.