"Radio Free Allston", the FM incarnation, did indeed operate at 106.1 with 20 watts from a whip antenna, IIRC. That was before I ever met Steve, so I'm not sure. I heard Vince tell the story about busting them at his retirement (from the FCC) dinner a few years back. I think RFA was nailed because it was one of the first really organized (snort!) FM pirates out there...moreso than any real interference to WROR or WMJX. Later as the pirate "problem" got worse and worse, the FCC seemed to get less and less interested in dealing with them. I think there's a host of factors behind that, but that was the end result.
Anyways, about a year after RFA was busted, Steve resurrected it as "Allston Brighton Free Radio". At first it was legal, using a Part 15 "talking house" transmitter on 1540 attached to the billboards on top of the old "Allston Mall". Later that moved to 1630, and another Part 15 AM Rangemaster transmitter on 1670 on top of 119 Braintree Street (the big factory-ish building by the Stop & Shop next to the Pike). ABfree operated legally this way for a few years, but eventually the crew gave up trying to be legal because it was so pointless; nobody could hear that 0.1 watt signal. :-\
I know a 20 watt carrier-current-style AM transmitter was found (probably on eBay), and coupled with a homebrew ATU and a homebrew TIS antenna on the roof of the studios. It worked reasonably well; you could hear ABfree for a mile or two in any direction. The station always had money problems, though...and after a few years the transmitter died and nobody could afford to replace it. That was the end of ABfree. Oh well.