jlehmann said:
Well there's definitely at least one more, 1400 WLLH has WLLH-1 in Lawrence, MA
Sorry, I overlooked the obvious old timer (and it was mentioned in that previous thread, too). But the station in Lowell doesn't officially have the -1 suffix; it's another case of a synchronized repeater without separate call letters. So here's a revised list for experimental stations (thanks, boiseengineer), some of which were mentioned earlier. It's not guaranteed to be perfect, of course, but all known operations, actual or "still listed" are included other than those in Puerto Rico:
KDTD 1340-a repeater with same calls for main station in Kansas City KS, status unknown
KHNU 620-two repeaters with same calls as main station in Hilo, Hawaii, one in Na`alehu and another in Kalaoa; Don Mussell reports, however, that main station in Hilo has been off the air since 2004 and Na`alehu is also silent
KKOB 770-230 watt nighttime-only repeater in Santa Fe for main station in Albuquerque; reportedly referred to internally as "KKOB-1" although not separately ID'd
KLSQ 870-East Las Vegas, still listed but was reportedly one of three such repeaters for the main station when it was in Laughlin NV which went off the air when the main station moved to Whitney NV (suburban Las Vegas)
KM2XVL 1220-a repeater in Huntsville TX for main station station in Madisonville
KQUE 1230-a repeater in northwest Houston TX for main station there, not on the air for years but still listed
WBZT 1230-a repeater with same calls in Pompano Beach for main station in West Palm Beach, reportedly off the air since the 1990's
WLLH 1400-historic synchronized operation ID'ing as "Lowell
and Lawrence" MA
WR2XJR 670-diplexed with WRJR 1010 Portsmouth VA, nighttime only repeating WMPH 670 Claremont VA; unclear why call letters are not WM2XPH
WS2XTR 1680 Evergreen Hills, VA-temporarily licensed for testing of a new design for medium wave antennas; apparently tests were done in 2002 but the record remains on file
WX4ESPN 98.1-134 watt experimental station at ESPN headquarters in Bristol CT; quoting Scott Fybush, "...being used as a testbed for advanced HD Radio services, including several all-digital modes and extended hybrid multicasting," not listed by FCC or on the ESPN affiliate site