Yeah, I could've phrased that better. I took it as a given that people knew that after 1978, all Class D's were required to attempt to upgrade to protected Class A status, and that WBRS tried to...but could not...upgrade to Class A on 91.7FM. The reason they couldn't is that WCRB 102.5 claimed I.F. interference; it was a known issue for WCRB employees driving to work on South Street would be listening to 102.5 and suddenly WBRS would appear as they went past the campus. The actual interference zone was small, but it had a big psychological impact.
IIRC, after the second failed application for Class A on 91.7, it quickly became apparent that WBRS was too late to the party and couldn't upgrade to Class A at any NCE frequency. That was what BEGAN the process that ended up with WBRS on 100.1FM, which eventually was finalized in 1984.
Re: the number of bays...did they start with FIVE or FOUR bays? I thought it was originally five bays from the start, not four. I knew they were polarized and I knew about the old 40w ERP; there's no way you could realistically get 40 watts out of a CP array using 10 watts TPO; you'd need an 8 bay full-wave antenna! But I thought they used five bays h-pol from the beginning...although looking at my chart, it does seem like an h-pol / five-bay / full-wave-spaced array would take 10 watts and spit out ~54 watts...and I don't remember WBRS ever having over 50 watts ERP.
FWIW, 40 watts h-pol is roughly the same as 25 watts c-pol/CP since CP gives you "twice" the wattage output. Yeah, yeah, I know it's not quite that simple, but for purposes of this discussion it's sufficiently true.
I do know about the story that there was a lot of problems with impedance matching with the five-bay CP array, and then in 1994 the top-most bay was destroyed by a lightning strike; I've seen the bay, it's sitting in the transmitter closet as far as I know and it definitely looks like it took a lightning hit. After that happened, they petitioned the FCC to allow WBRS to use 25 watts TPO (really more like 26) to achieve 25 watts ERP out of a 2-bay / full-wave-spaced array. The remaining four bays were reconfigured into a pair of two-bay arrays; a primary and a backup. To my knowledge they are the only grandfathered Class D FM to operate with more than 10 watts TPO, but admittedly I've never really dug around to confirm that.
I'd forgotten about that dorky provision that Brandeis had to sign an affidavit that there were no listeners to 99.5 or 100.7 on campus, because that was the only way that WZLX and WSSH (I think WSSH were the calls back then?) would sign off on the waiver of third-adjacent overlap. Seems almost quaint in today's world, doesn't it?
And yes, prior to WWFX 100.1 Southbridge increasing height and moving significantly eastward, WBRS did have a great signal. When I looked into whether they should convert the license to an LPFM, they actually would have to reduce their ERP slightly due to the height of South Hill! But when WWFX made that move in 1999 or so, it wiped out any WBRS coverage west of Rt.128 and really knocked down the fringe coverage to the north and south. The trees are less of an issue than you'd think; the antenna bays still have a pretty good "view" above them. It's that damn water tank about 300ft away that's a killer. It's a solid tube (not a bulb-with-legs) and taller than the Rabb Grad Center tower. Creates a giant "shadow" to the NNE and a huge multipath reflection, too. Around 2005-07 WBRS tried to convince the city of Waltham to let them move to the top of the water tank and it never got anywhere. (shrugs)
102.5 transmitting a few miles down the road in Needham was still a factor preventing a WBRS class/power increase on 91.7, but by then that had nothing technically to do with the South Street towers, the topic of this discussion.
@Eli: Yeah, I know it has nothing engineeringly to do with the South Street towers. But the point was that there might soon be no trace of anything radio-related at 750 South Street, and my point was that...while it's a stretch...while WBRS remains on 100.1FM, there will always be a legacy of there being SOMETHING radio-related at 750 South Street. One looks to preserve the past any way you can these days.
Speaking of the surroundings of an FM antenna: a substantial and tall building was constructed a couple of years ago right next to (and looming above) the WRBB-FM 104.9 antenna. Of course, WRBB's signal never travelled very far, thanks to WBOQ, but I wonder if this new structure made things worse.
I've done a little work for WRBB over the years. My hunch is that technically you are correct; the new building sure isn't helping. But WRBB's chief problems have primarily been WBOQ murdering their fringe coverage and the Prudential Tower's blanketing interference making on-campus reception a dicey proposition. The former would be helped if WRBB tried to move to 101.3FM (WFNX's old translator frequency) and I think you could make a case that WFNX would not receive any interference from such a move.
But nothing's gonna solve their on-campus reception problems with the Pru's blanketing; nothing short of getting a 1000 watt signal, anyways...which, of course, is impossible.
