Scott Fybush said:
PSFS is no longer an ideal place for an FM signal, what with the taller buildings that have gone up around it. I'd have to run a more detailed study to be certain, but I'm pretty sure 106.9 could at least come across the river into Center City. One Liberty would be a better site than PSFS, but if 106.9 needs a directional antenna to move there, there might not be the physical space for another antenna there. The Comcast building would be ideal, if only they'd allow broadcast antennas there...
I just took a quick look at WKDN's spacing situation in Camden.
The present site is short-spaced to the following:
WMHX 106.7 Hershey, PA
WLTW 106.7 New York
WWEG 106.9 Myersville (Hagerstown), MD
WEZX 106.9 Scranton, PA
WWZY 107.1 Long Branch, NJ
WFNE 106.7 North Cape MAy, NJ
WYPO 106.9 Ocean City, MD
WBYN-FM 107.5 Boyertown, PA
WKDN's present margin of clearance from WWYY 107.1 in Belvidere, NJ is only 2.5 kilometer (about 1.6 miles), so a move north to Market St would make this station short-spaced, then 73.215 contour protection would come into play.
Of the short-spaced stations, WBYN-FM wouldn't pose a problem since it is pre-1964 grandfathered on a third adjacent channel. However, if WKDN were to move to Center City, existing interference overlap to and from WMHX (major problem) and WWEG would need to be maintained, requiring an ERP reduction towards the west. Interference with WLTW and WWZY would probably shift a bit, but shouldn't change dramatically.
It looks like WKDN could move to Roxborough without violating 73.215 minimums, but the pattern would need to be tightened even more to satisfy protection towards the north and west.