A bit of firsthand knowledge.  A couple of things about FCP vs Master FM..  First, the Master FM at CN Tower was (originally) designed for omni-directional stations. Most of the stations in the early 70's were relatively grandfathered, in terms of their coverage - case in point CKFM, CHFI and CHUM FM.   CKFM, if memory serves me correctly was over 210 kw at the old CIBC building - and omni directional.  It's last "home" was on the "new" CIBC building at a relatively high power and omni-directional.   CHFI was at an even higher power from the CFTO tower in Agincourt.  So when they moved to CN Tower the Class "C" grandfathered stations were around 40 KW on Master FM.  CHIN FM was at a lower power because it is "B" class.  The Department of Transport (later ISED) wanted all Toronto area TV and FM stations to be clustered at one point.  When CKO came on the air, - which required a directional antenna at 99.1, it operated from FCP and various other stations followed. Many were licesned after the CN Tower master FM was built.    My recollection was that the CN Tower went into operation in 76, but the Master FM antenna was designed months or a couple of years before it was installed up there.  Antenna installation(s) took place in '75.

One other odd recollection.  I remember going up to the roof level of the "new" CIBC building when I worked at CKFM.  (before the windows were installed within the building) I took a portable TV up there and did some TV DXing.  This was when the CKFM antenna was being installed and the building was under construction.  That's a long time ago, a number of years before the CN tower went into operation.

 Most of the stations at FCP have highly directional antennas to protect U.S. and other Canadian stations on the same or adjacent frequencies.  Several were "drop in" frequencies - like 88,9 CIRV which originally operated at 88.7 (WBFO's frequency) and the arboriginal radio station on 106.5 (WYRK Buffalo).  (Classical) 96.3 "relocated" from an office tower in Mississauga and is directional to protect 96.1 Buffalo (formerly WJYE).   Other stations have literally been shoe-horned into the site, with specially designed antennas - i.e. 96.7 CFZM-FM-1. There have already been major changes to several FM antennas at FCP due to Safety Code 6 problems.  The problems included high levels of radiation over cooling towers on the roof. Several stations were required to re-design their antennas, to throw less RF onto the rooftop.  This antenna work occurred in May 2009 and included CFMZ, CBLA-FM and CJBC-FM.  There were some other Safety Code 6 issues when the outside (granite) cladding started falling from the face of the building.  There was a multi-year project whereby sidecars of workers (in side cars) were slung over the side of the building.  RF levels had to be reduced for some stations (that over and above the antenna design changes).  I believe that RF levels were reduced on "working" nights to accommodate the crews on the rooftop.  Every addition of an HD signal notches up RF levels a few hundred (or thousand) watts.  My recollection is that some prospective tenants proposed adding height to one or more of the towers, so that rooftop level RF could be reduced, or at least the stations requiring power increases, would not add to the RF at rooftop level.  Bottom line, FCP is basically "maxed out".  The remaining TV transmitters, which I believe are standby/auxiliary to the CN Tower (main) UHF transmitters, have not added to the SC6 problems.  This has been an FM issue, primarily.  I think that had Evanov been granted changes for Proud FM or CIDC at FCP, there would have been some significant power reductions that would have been required of incumbent stations.  The evanov applications were turned down on multiple occasions.  Skywave a big yellow board contributor may have additional first-hand knowledge.  FCP is also a very expensive place to do business. It is to my knowledge the only antenna site in the world, where the landlord charges an excess fee to stations for each HD subchannel that they use, after the main HD channel.   That surcharge works out to be around 10% of the cost to transmit from the building.   So, for example if the site rental fees were $160K per year for the main signal, the HD-2 would cost an additional $16K , plus some additional nickel-and-dime fees, including additional costs for the hockey-puck sized GPS antenna which is needed for HD operation.  To my knowledge there aren't similar HD2, HD3 etc costs anywhere in North America - by other landlords.  An FM station with 3 HD signals will be pushing $200K per annum, plus additional fees for standby generator, and other sundry costs imposed by Brookfield.   Clearly if you're operating an omni-directional station, CN Tower is a better location, particularly the "business" environment.  The building management at FCP has if I can use a phrase "take no prisoners" negotiating tactics.  And of course they have a number of tenants who couldn't relocate at any cost that would make business sense vs. the annual increases in costs charged by Brookfield.

Last edited by tvguy (June 17, 2021 3:44 pm)

It was a hot and muggy day. I remember because there was very little visibility.  No great tropo that day.  I was using something minimal like a 4-bay bowtie.   The Erie PA stations were certainly very strong at that elevation.  My recollection is that the flamethrower on Ch. 26  from Jamestown NY which was an indie that carried CFTO's programming a great deal of the time - was rock solid.   Only had a few minutes to try things out and the TV was a very heavy "transportable" - clunky - because it was of late 1960's vintage.  Commerce Court West was completed in '72, so I would have been up there in the summer of '71.  Not that many local (Canadian) TV stations on the air at the time.  My visit preceded Global, Citytv, Omni(s), and many other stations.  So there wasn't much on the air on UHF at that time in this area.  DXing would have been great - had there been an opening.  OECA (TVontario) would have been transmitting either from Canada Square or perhaps the old CBC tower on Jarvis St.

Last edited by tvguy (June 17, 2021 4:52 pm)

Wow great indepth info as always Tvguy!  Have you been or worked on CN yourself?

I was able to find a few photos in my library that might be of interest:

photo 1 - looking down, from the very top of the CN Tower mast, at a single panel of the original CITY-TV antenna.  It is located in the top aperture on the CN Tower (the red section).  The outer radome can be seen on the left and right side of the photo.  It is very tight up there (only 5 foot diameter).  There are some fine lines in the image due to RF radiation (from other TV transmitters).  This antenna is now out of service due to the repack.

photo 2 - a view (from 1979) looking down, from the CITY-TV aperture, into what was designated as "future antenna space".

photo 3 - an internal view, looking down, into the FM antenna section of the mast.  You will note there is a fair amount of space in this section.  I have highlighted a fellow climber in yellow, standing on a rest transition section, for reference.  A number of transmission lines can be seen along with a "spider" splitter to feed one of the tiers of the FM antenna.

photo 4 - a view of the top of one of the FM antenna dipoles.  The wire mesh, in the lower section of the photo, and behind the antenna acts as a reflector.  The inside, and curvature of the radome can be seen here.


 

Fascinating stuff, although I have to confess some of it is a bit above me (kinda like the CN Tower itself!) I really love the photos. They remind me of a great news serial City TV's Kevin Frankish once did. It was called "Hidden Toronto" and took viewers into places no member of the public could go so they could see what is normally off limits. (Backstage at a Mirvish play while it was in performance, for instance or at the City's water filtration plant to discover what goes on behind closed doors. That kind of thing.)  One of them was City's room (or whatever it was) on the CN Tower. 

I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!" 

It was a great 5-day series and I wish it was still around online. Really interesting look at places we were never meant to see. Years later, there would be an annual tour called Doors Open Toronto with a similar theme, but this was long before that. (And I think one of the Doors Open places they toured was the new City TV HQ at Yonge & Dundas. Talk about completing the circle!) 

Last edited by RadioActive (June 18, 2021 3:17 pm)

Skywave wrote:

My understanding is that the new Master FM antenna will occupy the aperture formerly used by CBLT Channel 5.  This will raise the centre of radiation by about 34 metres.  The Class C stations operating at 40 kW max ERP (for Class C equivalence) can reduce ERP to 32.5 kW.  This relocation has several benefits:
1) increases the distance to the Skypod, thereby reducing Safety Code 6 radiation.
2) lower transmitter output powers.  
3)increased headroom for the combiner and the antenna harness and radiators.

The CN tower master antenna is rated at a maximum of 150 kW per half..  The combiner is certainly at its limit, and in any event my understanding is that the bandpass curves were less than ideal for passing HD sidebands. A very important consideration with hybrid digital is the peak breakdown voltage which occurs when the digital carriers all add up.  For hybrid digital operation, the limiting factor for transmission lines and antenna harnesses is not so much the average power rating but rather the peak breakdown voltage.  This is a function of both the number of transmitters AND the power output of each transmitter.

Further to another question, CFTO-DT uses part of the original Channel 9 antenna, with the dipoles rotated from horizontal to add a vertical component, resulting in elliptical polarization.

Will this be the actual plan?  It does make perfect sense. Coverage might be even better!  Also, where did Bell stick their new HD radio antenna which im told is what caused that smoldering mess in 2017?

In Phase wrote:

RadioActive wrote:

One of them was City's room (or whatever it was) on the CN Tower.  I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!"

one more photo - the original CITY-TV transmitter at the CN Tower

lots of great movies and epic shows came out of that!  Unlike now...

In Phase wrote:

Tim Brown 2016 wrote:

tvguy wrote:

CHUM FM will not be running HD any time soon, from what I hear. 
The balance of stations which broadcast from the CN Tower, will need to have an upgrade to the "Master FM" antenna

Thanks for this tvguy... To be precise, is it not the CN Tower FM combiner that needs replacement to accommodate HD Radio? Why would the actual antenna need to be replaced? From what I recall (40 years ago), that's a broadband antenna up there. Is it a polorization issue?

The antenna itself probably does not need any changes as it is broadband.  The main issue is the FM combiner.
 
A multi-station combiner is really a set of filters interconnected such that all signals "combine" to feed a common antenna all the while preventing each stations signal from getting back into each other’s transmitter.
 
Due to FM band frequencies, each “filter” is physically large (about the size of a big hot tub), and there are multiple filters per station.
 
The filters are finely tuned to pass only a single FM station, within a specific frequency & bandwidth.  Adding HD signals expands the bandwidth such that the existing filters will chop off some of the HD signal.  Each stations series of filters would need to be retuned and/or replaced to permit HD transmission.  That’s a big job and would involve coordinating with all other players using the combiner.
 
Unfortunately, I don’t have a personal photo of the CNT FM combiner but a simple search reveals a picture taken by Mr. Fybush during one of his site visits.  Perhaps he has more images to share.

https://www.fybush.com/wp-content/uploads/2015/05/cn-combiner.jpg
 

 

Unfortunately the antenna cannot handle the peak voltage when all of the stations go HD!   Splitters and câbles will also need to be replaced.   

Plus when the HD is added into the safety code 6 calculations, the Space Deck becomes unusable!   Too much radiation.   So the best plan is to replace both antenna and combiner, from what understand and stick it in the aperture above, which is the old CBC channel 5 antenna space. 
 

In regards to the safety 6 regulation codes, is the now called “sky pod” formely spacedeck, actually safe this whole time with master fm literally above their heads?

CBLA-FM is limited to the equivalent of 50 kW at 150 metres effective height above terrain (Class B) to protect a 1st adjacent station in Rochester NY. As it is operating at 98 kW max at an EHAAT of 303 metres, it has a fairly deep null in the direction of Rochester.  CJBC-FM shares the same antenna and as a consequence is directional, although it could operate with full Class B omnidirectional parameters.

I wouldn't be surprised to see CBLA-FM move to the CN Tower with a directional antenna in the present Master FM aperture, which will become vacant.  CIUT and CJBC could be added into the new omni antenna operating with an equivalent ERP of about 4.5 kW. But I have no actual knowledge of any plans.

All the other stations on FCP are operating with directional antennas customized to maximize signal while maintaining all the requisite co-channel and adjacent channel protections to other stations.. It is possible to create different patterns for different frequencies using common panels, but that typically requires a combiner feeding each panel face  with different power ratios for each frequency.  The auxiliary antenna for CFMZ-FM is a variation on that.  It shares two panels of the CFZM-FM antenna and has a power split to feed a third panel pointing westward.

The plan is to use the new antenna for both the analog and digital signals.  Early implementations of IBOC sometimes used separate antennas for the digital component, but this does not work very well.  IBOC digital signals actually cause interference to the host analog FM signal, even when using the same antenna..  This interference is tolerable at injection ratios of up to -13 dBc per sideband (-10 dB overall).  But if a separate antenna is used this ratio will vary considerably because the centre of radiation and the vertical patterns don't match.  When CKFM and CHUM first tested HD, the HD component only was fed into the single bay antenna at the bottom of the Channel 9 aperture.  The analog signal was transmitted by the 5 bay FM antenna below.  It was predicted beforehand that concentric donuts of interference would exist in the downtown core, and the actual tests determined that these zones of interference were unacceptable.  So CKFM is transmitting both signals from the single bay antenna at reduced ERP on an interim basis (shown as TO "temporary operation" in the ISED database),

In Phase wrote:

RadioActive wrote:

One of them was City's room (or whatever it was) on the CN Tower.  I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!"

one more photo - the original CITY-TV transmitter at the CN Tower

Are those a pair of British Pye TVT transmitters?, or like Monty Python says... Am I very much mistaken ? 

Are they working as main and back-up or are they running in parallel operation?

Tim Brown 2016 wrote:

Glen Warren wrote:

I was under the belief that TVO/OECA was transmitting Channel 19 from the CBC tower at Jarvis St. until they moved facilities to the CN Tower.

Speaking of TVO... Why doesn't TVO broadcast TFO on a subchannel of RF 19? Would it really cost that much?

Here in Peterborough/Northumberland, Global Toronto is about to be added as a subchannel to the CHEX RF 12. In fact, it may have already happened. This is to replace the coverage lost by the shutdown of RF 27 in Baltimore, ON.

TFO was separated from OECA in 2007 and now exists as a stand alone crown entity with its own mandate and government funding (and more recently, it's own share of hi jinx, and Executive / HR shenanigans making it into the public purview)

La Chaine/TFO only had 3 high power analog transmitters, and about a dozen LPTV transmitters, all of which were shutdown with the transition to HDTV service in Canada at the end of August 2012. The majority of the TFO transmitters were in Eastern Ontario, the Ottawa Valley, and Northern Ontario.  TFO never had a conventional transmitter in Toronto. La Chaine/TFO had mandatory coverage on Ontario cable TV systems, and later on DTH satellite.
 

Glen Warren wrote:

In Phase wrote:

RadioActive wrote:

One of them was City's room (or whatever it was) on the CN Tower.  I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!"

one more photo - the original CITY-TV transmitter at the CN Tower

Are those a pair of British Pye TVT transmitters?, or like Monty Python says... Am I very much mistaken ? 

Are they working as main and back-up or are they running in parallel operation?

The transmitter has an interesting history.

It began CITY-TV life at Canada Square (Yonge & Eglington) on channel 79.  It was subsequently moved to the CN Tower.  It was really a design by George Townsend (who made Townsend transmitters in the 1970's and 80's, which morphed into Comark, and is now known as Hitachi Kokusai Electric Comark).  At some point in the late 1970's, probably with the move to the CN Tower, the exciters (main & backup located in the centre cabinet) were changed to PYE TVT to increase stability and reliability.  Curiously, the transmitter manuals had "AMPEX" on them, but the cabinets had CCA logos on the front.  It seems there were a few different companies or people that had a hand in this transmitter.

The high power amplifiers were klystons.  There was a Visual amplifier (the left cabinet) and an Aural amplifier (the right cabinet) and the two signals were externally diplexed before feeding the antenna,  Each amplifier was wideband tuned so that if necessary, a single klystron amplifier could amplify both aural and visual, in an internally diplexed mode, at reduced power.

The output of the transmitter was about 15kW visual and 1.5kW aural.  The transmitter was water cooled and consumed about 200kW of power to produce the 15kW output so it was incredibly inefficient.

Th channel was changed to 57 in 1983.

It was replaced with a more efficient fully solid state transmitter around 1992.  At the time, it was the highest powered, solid state UHF TV transmitter in North America.
 

Now here's another blast from the past that I never knew about. This is from Dec. 1973 about a fight local TV and radio stations had about who could get an antenna spot on the then-still-to-be-finished CN Tower. I don't recall these battles back then, but they obviously happened. 

To me, though, the biggest irony has to be CFTO owner John Bassett actually trying to make this claim over providing a stronger signal into Buffalo (and by extension the Niagara Falls, Ont. area) for Toronto's Channel 9:

"We believe that our programming is more appealing than that of the Buffalo stations, and we believe that if we are given an opportunity to project our signal as clearly as the Buffalo stations into that populous area, that we can beat them, as we have done in Toronto, and bring these Canadian viewers back to Canadian television." 

"More appealing programming?" Really? Even though most of that "programming" was purchased U.S. imports even back then? That, as my late and very great grandma used to say, is a lot of chutzpah! 

Oh, and I love the thought of CHIN being overpowered by CKFM on cheap Japanese radios! Not to mention the unrelated story of CJRT on life support. What an insane year that must have been!