Philadelphia Radio Frequencies

[ty_kleinle]

Anyone ever notice that the radio stations in Philadelphia are either exactly two Mhz above the New York Stations or the same? Example:
WNOW-92.3 (92.5 in philly)
WPLJ-95.5 (95.7 in philly)
WXNY-96.3 (96.5 in philly)
WSKQ-97.9 (98.1 in philly)
WPEN-98.7 (98.9 in philly)
Then Z100 shares 100.3 with WRNB
CBS-FM shares 101.1 with WBEB
WWFS-102.7 (102.9 in philly)
WAXQ-104.3 (104.5 in philly)
WQXR-105.9 (106.1 in philly)
WLTW-106.7 (106.9 near philly)
Anyone else ever notice this?

 

[w9wi]

More or less intentional.

Stations in the same city must be at least 0.8MHz apart -- 92.5/93.3/94.1/etc... To get the most channels available in any given city -- 20 -- those channels must all be at the minimum spacing. So NYC gets 92.3/93.1/93.9/94.7/etc..., and if Philly gets 92.5 then for maximum spectrum efficiency it also gets 93.3/94.1/etc.

Why did Philly start with 92.5 instead of 92.1 or 92.7? For many years, certain FM frequencies were reserved for lower-powered Class A stations. 92.1 was one of these Class A frequencies -- and if you went up in 0.8MHz steps from there, you hit a total of eight Class A frequencies. If Philadelphia had started with 92.1, 40% of the city's stations would have been greatly limited in power.

It'd be worse if you started with 92.7. 92.7 was also a Class A frequency -- and if you went up in 0.8MHz steps from there, you hit *12* low-powered Class A frequencies.

So why is there no 99.7? Why is WRNB on 100.3 instead of 100.5, and WBEB on 101.1 instead of 101.3?

Good question. Best guess: 101.3 in Lancaster has been around forever -- it predates WBEB. Of course, Lancaster is far too close to Philly to allow use of 101.3 in both cities. Once you put WBEB on 101.1 to avoid Lancaster, that ruled out use of 100.5 in the Philadelphia area -- and then when you went to 100.3 instead, that ruled out 99.7. 99.5, luckily for WUSL, is in Delaware -- far enough away that 0.6MHz is enough separation. You can't put Lancaster on 101.1 instead, because it's too close to the 101.1 station in Washington.

At least that's my guess. I'm sure Scott Fybush would have the real story...

_________________________________________________

If you do some digging you'll find that Chicago and LA also use the 92.3/93.1/93.9/etc. plan. And Milwaukee -- about the same distance from Chicago as Philadelphia is from NYC -- uses many of the same channels, for the same reason. (92.5/93.3/95.7/96.5/97.3/102.1/102.9/103.7/105.3/106.1/106.9/107.7)

 

[DanStrassberg]

Anyone ever notice that the radio stations in Philadelphia are either exactly two Mhz above the New York Stations or the same?

You mean 200 kHz--not 2 MHz.

 

[BobSmolarek]

Philly should have been on 99.7, 100.5, and 101.3. But to untangle this to make it right would be a nightmare. Starting with 101.3 in Lancaster, then 100.5 is too close to 100.7 Allentown, 99.7 too close to Easton 99.9. Then all the new stations like 99.7 in Tuckerton!!

 

[Steve Green NEPA]

>> ' ....If you do some digging you'll find that Chicago and LA also use the 92.3/93.1/93.9/etc. plan. And Milwaukee -- about the same distance from Chicago as Philadelphia is from NYC -- uses many of the same channels, for the same reason. (92.5/93.3/95.7/96.5/97.3/102.1/102.9/103.7/105.3/106.1/106.9/107.7) .....' <<

Adding to that, Baltimore/DC and Detroit use that first sequence. And iIrc, those markets all fall in line with the VHF television channels 2, 4, 5, 7, 9, 11, 13