FM stations- Doubling up

[Big 121]

Yes , the FM's have been at it too. KOGO's towers host 106.5(west) and 97.3(west).
Others include=
101.5 and 93.3 diplex, near 54th street
102.9 shares with newcomer 102.1 on Soledad
100.7 combines 98.1, and 94.9 on Soledad. 89.5 soon to join them.
94.1 combines 96.5, 103.7 and 105.3 all on 1 array on Soledad .
Years back, the RF field from Ch. 8 and 10 were so strong, nearby homes' flourescent tubes would be "on" until the
stations signed off at night.
Quite an engineering feat for the quad stations to keep spurs and intermod levels legal. All that and HD, too.
Big 121

 

[davideduardo]

Yes , the FM's have been at it too. KOGO's towers host 106.5(west) and 97.3(west).

FM statations have been side mounted on AM station towers since the 40's. Today there are far fewer of them, because FMs have been viable for decades and can afford to be at higher locations than most AMs choose to locate at. Generally, a good AM site is a bad FM site.

101.5 and 93.3 diplex, near 54th street

I don't think they are diplexed... I think the KGB main antenna and the KHTS auxiliary antenna are at the same site, but they have different heights, meaning the aux antenna is lower than the KGB antenna.

102.9 shares with newcomer 102.1 on Soledad
100.7 combines 98.1, and 94.9 on Soledad. 89.5 soon to join them.

These have separate antennas. There are some shared towers, but not antennas. 100.7 and 98.1 have antenna heights that are different by 20 meters. Two antennae, one tower...

94.1 combines 96.5, 103.7 and 105.3 all on 1 array on Soledad .

These are combined in a single ERI antenna. KYXY also has an alternate at same power on another tower.

Quite an engineering feat for the quad stations to keep spurs and intermod levels legal. All that and HD, too.

It's not a big engineering feat... the technology and the mechanics of using a single antenna have existed for decades... witness several generations of combining many, many FMs on the Empire State Building systems. The main issue is having a broadband antenna and rejection networks for each insertion point.

 

[RadeoEngineer]

Yes , the FM's have been at it too. KOGO's towers host 106.5(west) and 97.3(west).

102.9 shares with newcomer 102.1 on Soledad
100.7 combines 98.1, and 94.9 on Soledad. 89.5 soon to join them.

These have separate antennas. There are some shared towers, but not antennas. 100.7 and 98.1 have antenna heights that are different by 20 meters. Two antennae, one tower...

Actually David those stations are on a single antenna. You may be reading inaccurate info somewhere, but I was involved in the installation of that system.

 

[136kgb]

David you are incorrect also concerning KGB-FM and KHTS, they are both on a combiner fed into a single antenna at the 52nd street transmitter site. The seperate antenna you see is the HD for KHTS. On the KOGO towers the North east tower (tower 1) is 106.5, as well as it is fed by a combiner that serves as an aux for some of the CC stations. The South west KOGO tower (tower 2) is 97.3 alone.

 

[davideduardo]

David you are incorrect also concerning KGB-FM and KHTS, they are both on a combiner fed into a single antenna at the 52nd street transmitter site. The seperate antenna you see is the HD for KHTS. On the KOGO towers the North east tower (tower 1) is 106.5, as well as it is fed by a combiner that serves as an aux for some of the CC stations. The South west KOGO tower (tower 2) is 97.3 alone.

Then there is a mistake on the FCC database, or something has changed in the facility, as the FCC lists separate elevations for each station... elevations that correspond to about the right distance between two different antennas.

KHTS has antennas on two different structures licensed, booth at 26.5 kw ERP.

 

[davideduardo]

Yes , the FM's have been at it too. KOGO's towers host 106.5(west) and 97.3(west).

102.9 shares with newcomer 102.1 on Soledad
100.7 combines 98.1, and 94.9 on Soledad. 89.5 soon to join them.

These have separate antennas. There are some shared towers, but not antennas. 100.7 and 98.1 have antenna heights that are different by 20 meters. Two antennae, one tower...

Actually David those stations are on a single antenna. You may be reading inaccurate info somewhere, but I was involved in the installation of that system.

FCC is the source. 102.9 and friend are same HAAT, antenna height, etc. But I was referring to, as I specifically mentioned, 100.7 and 98.1 which are 20 meters apart in height, and show different Dielectric antenna types. I don't understand how the two stations in reference, KIFM and KFWB, could be diplexed with this data.

http://www.fcc.gov/fcc-bin/fmq?list=0&facid=42117
http://www.fcc.gov/fcc-bin/fmq?list=0&facid=34589

 

[Big 121]

Ahhh, New York city again. Having been a resident of both White Plains and West Islip, I'm familiar with the setups that were used on both the Twin Towers
and the slant dipoles on Empire State bldg. And all the AMs in the Jersey bogs.Soledad had it's own growing pains as the FM's moved there. Multiple lower
power spurs were audible many miles away, the most famous was on 106.9 and covered to Descanso. They have since done an admirable job of cleaning
up those unwanted products, except for one mix on 104.1 . And no, its not my receivers...
Chula Vista suffers from TJ's powerhouses, with numerous mixes occuring across the band on open channels.
As far as KIFM and KFMB FM, their antenna centers are both 38 meters above ground, on the same tower.
102.1 and 102.9 use a PSI wideband, one that looks like a copper project from the Ham Universe website. And a "fine match" for those pesky reactances.
As far as using the FCC database, I"ve found so many errors; it's just not that current....
Our local eng. types are the most reliable.
Big 121

 

[RadeoEngineer]

Yes , the FM's have been at it too. KOGO's towers host 106.5(west) and 97.3(west).

102.9 shares with newcomer 102.1 on Soledad
100.7 combines 98.1, and 94.9 on Soledad. 89.5 soon to join them.

These have separate antennas. There are some shared towers, but not antennas. 100.7 and 98.1 have antenna heights that are different by 20 meters. Two antennae, one tower...

Actually David those stations are on a single antenna. You may be reading inaccurate info somewhere, but I was involved in the installation of that system.

FCC is the source. 102.9 and friend are same HAAT, antenna height, etc. But I was referring to, as I specifically mentioned, 100.7 and 98.1 which are 20 meters apart in height, and show different Dielectric antenna types. I don't understand how the two stations in reference, KIFM and KFWB, could be diplexed with this data.

http://www.fcc.gov/fcc-bin/fmq?list=0&facid=42117
http://www.fcc.gov/fcc-bin/fmq?list=0&facid=34589

I know you meant KFMB where you wrote KFWB, but I can assure you it's the same antenna for KFMB-FM, KIFM, and KBZT. It's a Dielectric antenna hung on the KFMB TV tower. I can also assure you all of the proper paper work was filed, as this project included some very highly qualified people. Someone at the FCC may have made an error but I was there for every step of the transition of KIFM and KBZT to that system. Early on, KYXY (96.5) was also on that system but subsequently moved across the street to the KGTV site. I can't speak to why there is a different antenna type shown for KFMB-FM and KIFM, but can only assume any mistake made happened in D.C. and not in San Diego. I suppose all of the applications could be reviewed online if you're that interested.

 

[fybush]

I'm looking at the CDBS data for the three "Quadzilla" stations on Soledad. All three are consistent in the "height above ground" field, agreeing that the antenna center of radiation is 38 meters up. Where the inconsistency comes in is in the RCAMSL and HAAT fields, where 100.7 reports in at 269 meters AMSL while 94.9 and 98.1 show 271 meters AMSL. And that, in turn, changes the HAAT calculation for 100.7, and rather dramatically at that: it shows up at 189 meters AAT instead of 209 meters for the others, which in turn gives KFMB 30 kW instead of 26.5 for the others.

I concur, having seen it, that it's really just one antenna (and a very impressive combiner) for all four stations.

 

[davideduardo]

I know you meant KFMB where you wrote KFWB,

I'm dyslexic. Thanks for reminding me.

but I can assure you it's the same antenna for KFMB-FM, KIFM, and KBZT.

With both your and Scott's explanation, I will chalk this up to FCC mysteries. I should have just limited myself to telling big 121 that diplexed and multiplexed stations is hardly a trend, as he seems to think.