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The rotary phase maker

I alluded to this in an earlier post: Open Delta three phase service.  Some transmitter sites are fairly remote and three phase power is not available.  Occasionally, with lower powered radio stations, this is acceptable because those transmitters can be configured to run on single phase power.  However, almost any transmitter above five kilowatts or so will require three phase power.  This is the case at the WQBJ transmitter site in Palatine Bridge, NY.  The site is located in the middle of farm land and only has single phase service.  The nearest three phase service is several miles away and the utility company wants several hundred thousand dollars to upgrade the line.

WQBJ transmitter site electrical service

WQBJ transmitter site electrical service

The station is a class B FM with a six bay full wave spaced antenna.  Even so, the TPO is 17 KW, which makes some type of three phase service a requirement.

WQBJ six bay Shively 6810 antenna

WQBJ six bay Shively 6810 antenna

The main transmitter is a Broadcast Electronics FM30B, which is now 25 years old.

WQBJ main transmitter, Broadcast Electronics FM30B

WQBJ main transmitter, Broadcast Electronics FM30B

The backup transmitter is a CSI FM20T, which is almost forty years old.

WQBJ backup transmitter, CSI FM20T

WQBJ backup transmitter, CSI FM20T

Rather than do an open delta service, which is not desirable for several reasons, both transmitters have their own rotary phase makers.  From a reliability and redundancy standpoint, this is the right way to equip this site.  The rotary phase makers are essentially a motor generator combination which takes the split phase power and generates a third phase.

WQBJ phasemaster, backup three phase converter

WQBJ Phasemaster type T, backup three phase converter

Phasemaster parallel connection diagram

Phasemaster parallel connection diagram

The phasemaster is is a 40 KVA unit and is connected to the backup CSI transmitter

WQBJ Roto Phase, main three phase rotary converter

WQBJ ARCO Roto Phase, main three phase rotary converter

The Roto Phase unit for the main transmitter is actually two 40 KVA units connected in parallel through dry core isolation transformers.  Incidentally, the Roto Phase units need to have their bearings changed every ten years or so.  This requires the units be disconnected, placed up on their end.  To get the old bearing out, the housing has to be cooled with liquid CO2.  Both units are due for new bearings soon, which should be a pleasant job indeed.

Repairing the Nautel VS2.5 transmitter

The newish Nautel VS2.5 transmitter installed at WJJR had an RF module failure. This particular model transmitter does not have slide in RF modules as other Nautel transmitters do.  To fix this transmitter, it has to be pulled out of the rack, flipped over and opened from the bottom. The module replacement is very straight forward, there are five solder pads that connect to wires carrying the input, output, power supply and bias voltages.

Nautel VS2.5 transmitter RF modules and combiner

Nautel VS2.5 transmitter RF modules and combiner

The troubleshooting guide gives good instructions on how to check the PA MOSFETS with a DVM. I found that 1/2 of the device in PA1 was bad:

Schematic Diagram, NAPA31

Schematic Diagram, NAPA31

All in all, not a very hard repair. This was under warranty, so a replacement RF pallet was sent to the station without charge. The problem is more about where the transmitter is located:

Killington Mountain, Killington, VT

Killington Mountain, Killington, VT

Killington Peak is the second tallest mountain in Vermont, topping out at 4,235 feet (1,291 meters). In the winter, one can take the chair lift to the top. In the summer, the road is drivable with a four wheel drive. In those in between months, access to the top can be very tricky at best. We had a pretty wet spring this year, so the roads up the mountain are just now becoming passable for vehicles.

Even after reaching the parking lot, there is still a 10 minute walk to the peak, another 200 or so feet up a steep, rocky trail.

Further complicating things, this transmitter is wedged into this little shack, which holds; a BE FM3.5A transmitter (defunct WJJR), a Harris HT3 transmitter (WZRT), an ERI combiner, two racks of equipment (STL’s, Exciters, remote controls, etc) a backup QEI transmitter, an Onan generator transfer switch:

Killington Peak fire tower, WJJR WZRT transmitter building

Killington Peak fire tower, WJJR WZRT transmitter building

Both stations run into this ERI half wave spaced antenna:

WJJR WZRT ERI antenna

WJJR WZRT ERI antenna

It is very tight in this transmitter room. There is a new tower on Killington Peak, which is still under construction. At some point, the plan is to move into the larger building next to the new tower.

Killington Peak tower

Killington Peak tower

On a clear day, the view from the top is spectacular. On this day, the peak was in the clouds, so not so much:

Killington Peak view

Killington Peak view

It is a great site, the HAAT is 2590 feet (790 meters) and the stations carry forever on relatively low power outputs.

North Adams tower update

As promised in an earlier post, here is an update on the progress at the North Adams tower site for the restoration work on WUPE-FM and WNNI. For those unfamiliar, refer to this post: North Adams Tower Collapse.

A contractor installed a 70 foot wooden utility pole last week.  We ordered new Shively Versa2une FM antennas as replacements for the antennas destroyed when the tower fell last March.  These new antennas are field tunable, which is a nice feature.  The idea is that this pole will be used until the replacement tower is constructed, which is many months away.  After the new tower is up, I would like to keep the pole in place as a backup facility for both stations.

North Adams restoration work

North Adams restoration work

The bucket truck arrived but the driver had a bit of bad news; there is room for only one person in the bucket. The boss pipes up and says “Oh, that’s okay, Paul can go up and run the bucket”

WAT!

Are you sure this is a good idea?

Are you sure this is a good idea?

So anyway, it turns out running a bucket truck is not a huge deal; there is a joy stick of sorts that moves the booms around, up down, sideways, etc. Once you get the feel for it, it is pretty easy and three dimensional movement becomes second nature.  That being said, at 70 feet in the air, everything gets a little wobbly, so it is best not to jerk the controls around.

The antennas were mounted on a 2 inch pipe which was attached to the pole with 1/2 inch threaded rod. We left a little bit of pipe sticking up above the top of the pole to get the FM antennas as high a possible.

Mounting pole to tower

Mounting pole to tower

Mounting pole to tower

Mounting pole to tower

Some dude in a hang glider checking out the work

Some dude in a hang glider checking out the work

Getting photobombed by some guy in a hang glider is a new experience.  No day is exactly like another in this line of work.

WUPE and WNNI temporary antennas

WUPE-FM and WNNI temporary antennas

The antennas were tuned up once they were up on the pole. We did this with the network analyzer, which made the job very easy. WUPE-FM (top antenna) started using this antenna on Wednesday afternoon (5/7) with greatly increased power output.   This gets the station almost the same coverage area as they had before the tower collapse.  We tested WNNI (bottom antenna) and it all looked good. WNNI is still waiting for a temporary wireless internet feed for program delivery. Once that is established, we will have to do the intermod measurements one more time before they can go on the air.

Here are some pictures of the cleaned up site:

North Adams, fallen tower removed

North Adams, fallen tower removed

North Adams, fallen tower removed

North Adams, fallen tower removed

The temporary monopole being used by the cell providers:

North Adams temporary cell tower

North Adams temporary cell tower

Basically the pole is ballasted in place by those huge concrete blocks.

WEBE pictures

WEBE is fairly unique in that its antenna is mounted on the side of a 500 foot smoke stack. I took a few pictures last winter:

WEBE Main antenna

WEBE Main antenna

This is a close up of the Antenna:

WEBE main antenna, Shively 6 bay half wave spaced

WEBE main antenna, Shively 6 bay half wave spaced, ERP 50 KW

Here is an even closer view from a different angle:

WEBE main antenna, courtesy of NECRAT

WEBE main antenna, courtesy of NECRAT

From this angle, one can see the mounting brackets and the wire mesh reflector installed on the smoke stack.  From the first picture, one can see that the 400 MW PSEG coal fired power plant puts out a lot of combustion products when on line.  Combustion is an exothermic chemical reaction which looks like this:

Hydrocarbon Fuel + Oxidizer + Nitrogen  → Heat + CO2 + H2O + NOx

Included in this are any trace elements that are found naturally in the coal that is being burned.  These include things like Mercury, Nickel, Uranium, et cetera.  These trace elements can concentrate around the smoke stack because they fall out of the particulate quickly and these plants burn a lot of coal.  The above picture was taken on a very cold day, most of what is coming out of the smoke stack is steam.

The issue for the radio station is when the particulate matter accumulates on the antenna, effectively shorting it out.  The solution was to place the RADOMES around the elements and then constantly purge the RADOMES with nitrogen.  Thus, this liquid N2 tank is vital for the operation of the radio station:

Liquid Nitrogen Tank

Liquid Nitrogen Tank

Each element of the antenna has a small hole in the feed line. N2 is fed continuously into the transmission line at a pressure of about 1.5 inches water column which then purges the RADOMES keeping any combustion products out of the RADOMES.  The N2 tank needs to be changed out every 18-21 days and weights over 650 pounds when full.

North Adams Tower Collapse

High winds seem to be the culprit in the collapse of two towers in North Adams. According to the Motorola system technicians, it happened at about 12:30 am Sunday morning, which is when all their link loss alarms started going off.  The larger, self supporting tower broke from it’s mounting plate and tipped over into the smaller guyed tower next to it. Effected are WUPE-FM and W226AW (WFCR New England Public Radio) as well as NEPR new station WNNI which has not officially signed on.

Cellular service for ATT, Verizon and Sprint/NEXTEL were all knocked off line as well internet services and E911 dispatch.  Those services are coming back on line, with temporary modular cell units en route. News report from WWLP channel 22, Springfield, MA:

Here are some pictures:

North Adams Cell Tower

North Adams Cell Tower

WUPE-FM antenna on the ground

WUPE-FM antenna on the ground

WUPE-FM antenna

WUPE-FM antenna

WUPE-FM STL dish

WUPE-FM STL dish

Base of WUPE-FM (formerly WMNB) tower

Base of WUPE-FM (formerly WMNB) tower

WNNI antenna

WNNI antenna

WUPE-FM WNNI and W266AW transmitter building

WUPE-FM, WNNI, and W266AW transmitter building

North Adams Cell Tower

North Adams Cell Tower

North Adams Cell Tower

North Adams Cell Tower

North Adams Cell Tower

North Adams Cell Tower

North Adams Cell Tower

North Adams Cell Tower

Tower base mounting plate, apparent failure point

Tower base mounting plate, apparent failure point

Tower base mounting plate

Tower base mounting plate

Tower Base Mounting Plate

Tower Base Mounting Plate

For pictures of the towers during happier times, refer to this post: Filtering for co-located FM transmitters.

Restoration work is underway with WUPE-FM expected to return to air at low power by Monday afternoon.

Update:

WUPE-FM was returned to air at low power by about 1pm on Monday 3/31.  We took an unused Shively 6812 antenna that was tuned to 94.1 MHz and retuned it to 100.1 by cutting 1/4 inch pieces from the end of the elements until it was on frequency.  It took a bit of doing, but with a network analyzer, we were able to get it to 1.2:1 SWR with symmetrical sidebands.  Running 600 watts, it covers the city of license and then some.

WUPE-FM temporary antenna

WUPE-FM temporary antenna, Shively 6812

The STL antenna is a survey antenna mounted on the side of the building. In this configuration, with the leaves off of the trees, we are getting about 250 uV signal, which is pretty good.

WUPE-FM temporary STL antenna

WUPE-FM temporary STL antenna

The site is now crawling with insurance investigators, cell site technicians, North Adams fire department, Berkshire County Sheriff’s officers, tower workers, etc.  After we finished this work, we cleared out to make more room for everybody else.  Estimated restore time for W266AW is Wednesday 4/2.

Planning for the replacement tower is already in progress, I’d expect it to happen fairly quickly. The next step for the broadcasters is to put up a 70 foot utility pole and get a full powered antenna for WUPE. This should happen in the next two weeks or so. That will serve as the temporary facility until the new tower is constructed.

Filtering for co-located FM transmitters

Well sited FM transmitter locations usually want some height above average terrain. This means either a tall tower or a high hill or mountain. Once a site is developed, co-location of other FM transmitters often happens because sites are expensive to develop. A second station can save money by using existing facilities.

For all those newly permitted LPFM stations; pay attention. If you are going to be co-located at an existing FM broadcast site, you may need to do this too.

Interference from intermodulation mixing products can develop when FM transmitting antennas are in close proximity.  This is especially true with solid state, broadband PA commonly used in today’s VHF FM transmitters.  Thus, when antennas are closely placed, external filtering is required.

WUPE FM transmitter site, North Adams, MA

WUPE FM transmitter site, North Adams, MA

This is the case with a current project in North Adams, Massachusetts.  New England Public Radio is placing WNNI on the air from the WUPE-FM site.  WNNI is using one of those new Harris (now GatesAir?) Flexiva transmitters and WUPE-FM uses a Crown FM-2000A.  The antennas are on separate towers, but the towers are in very close proximity, about 30 feet apart.  In order to avoid any possible problems, a Shively 2602-3A-FB 3 pole filter was installed on each station.  The filter is a band pass for the station installed on and a notch for the other station.

The primary concern here is mixing products between the two transmitters.  Both have broad band solid state amplifiers with low pass filters before the output connector.  There are three frequencies of interest;

  1. (F1 – F2) + F1 or (100.1 MHz – 98.9 MHz ) + 100.1 MHz = 101.3 MHz
  2. F2 – (F1 – F2) or 98.9 MHz – (100.1MHz  – 98.9MHz) = 97.3 MHz
  3. F2 + F1 or 100.1 MHz + 98.9 MHz = 199 MHz

That, plus harmonic measurements out to three or four harmonics of the fundamental frequency should be enough to demonstrate compliance with FCC out of band emissions standards.

Measurements on these frequencies must meet the emissions standards outlined in FCC 73.317 (d), which states:

Any emission appearing on a frequency removed from the carrier by more than 600 kHz must be attenuated at least 43 + 10 Log10 (Power, in watts) dB below the level of the unmodulated carrier, or 80 dB, whichever is the lesser attenuation.

It is also noted that this site has several cellular carriers and no doubt has or will have LTE at some point. We all know that rural LTE installations can create self induced problems, which are then conveniently blamed on the nearest broadcast station because, hey, why not?

To further complicate matters, New England Public Radio also has a translator, W266AW (101.1 MHz) on the same tower as WNNI.  The same measurements noted above will have to be preformed again for the translator.

WNNI FM transmitter and Shively filter

WNNI FM transmitter and Shively filter

WNNI equipment rack.  This is one of those new Harris (GatesAir?) Flexiva FM transmitters.

WUPE-FM Shively Filter

WUPE-FM Shively Filter

WUPE FM filter installation

wave spaced Shively antenna.  Antenna for W266AW below

WNNI 4 bay half wave spaced Shively antenna. Antenna for W266AW below

New WNNI antenna mounted on cell tower next to WUPE-FM tower. The W266AW translator antenna is directly below WNNI’s main antenna.

WUPE-FM 3 bay half wave spaced Shively antenna

WUPE-FM 3 bay half wave spaced Shively antenna

WUPE-FM antenna installed on the original broadcast tower.  I believe the tower dates from 1959 or so.

It is important to get this type of installation right the first time.  Creating interference all around or above the FM band is never a good strategy.  Going back to ask for more funds to make something right is also highly frowned upon.

Building the FM band

WFLY transmitter site, August 1949

WFLY transmitter site, August 1949

Several years ago, I rescued a old filing cabinet that was being trashed. This particular file cabinet was moved to a transmitter site during the great radio consolidation of the late 90’s and early 00’s. In it, I discovered a treasure trove of early documents about two radio stations from the Albany NY area. I thought it would be interesting to document the building of one of the early FM stations in Albany, WFLY.

Albany is the capital of New York.  There were several early (prior to 1940) AM radio stations in the Albany area:

  1. WGY previously owned by General Electric in Schenectady, signed on in 1922
  2. WHAZ, previously owned by RPI (Rensselaer Polytechnic Institute), signed on in 1922
  3. WOKO (now WDDY), signed on in 1930
  4. WABY, (now WAMC-AM), signed on in 1934

General Electric, who worked closely with RCA in radio development and experimentation, was working on TV in 1928 and FM radio in 1938/39.  There were also several early (prior to 1950) FM stations in the area:

  1. GE owned W2XOY on 48.5 MHz (circa 1939), later W85A, WGFM, and WRVE 99.5 MHz.
  2. Independently owned W47A on 44.7 MHz (circa 1940), later WBCA 101.1 MHz, now gone.
  3. WTRY owned  WTRI-FM on 102.7 MHz (circa 1947), off air by 1954.  102.7 frequency later used by WEQX in Manchester, VT
  4. Troy Record owned WFLY on 92.3 MHz (circa 1948).

These stations operated from transmitter sites in the Helderberg escarpment on land that was formerly owned by the Albany Bible Institute.  It is interesting to note that two of the four FM stations did not make it past 1955. In 1967, WTRY did make a second attempt at FM, launching WDKC on 106.5 MHz, which is today known as WPYX.

It would appear the Troy Record initially applied for an FM broadcasting license in late 1946.   The paper trail that I have starts in early 1947, when the station hired a consulting engineer Ernest Barbeau of Schenectady to oversee the construction process for the studios and transmitter site.  Ernest Barbeau, in an introductory letter to Frank York, publisher of the Troy Record, notes himself as a former GE engineer and assistant to W.R.G. Baker, General Electric’s television pioneer.  At the time, it was already understood the height means almost everything in FM broadcasting.  There are several letters dealing with land acquisition and transmitter building construction.

Below is a chart of all the various Barbeau letters written in 1947.

Date From To Subject
Jan 3, 1946 (sic) Barbeau York FM CP granted
Feb 5, 1947 Barbeau York Studio location
Feb 8, 1947 Barbeau York Coverage area, transmitter power, tower type
Feb 21, 1947 Barbeau York Scheduling
Mar 7, 1947 Barbeau York Transmitter/tower type, with attachments
Mar 9, 1947 Barbeau York Electric/phone service
Mar 15, 1947 Barbeau York DC consulting engineer John Barrons
Mar 23, 1947 Barbeau York Scheduling
Mar 29, 1947 Barbeau Williams Transmitter site location
Mar 29, 1947 Barbeau York Transmitter site location, studio location
Mar 23, 1947 Barbeau Barrons Transmitter site location
Apr 4, 1947 Barbeau York Helderberg land owners
Apr 4, 1947 Barbeau Rogers Camp Pinnacle
Apr 9, 1947 Barbeau York Transmission line
Apr 9, 1947 Barbeau Van Antwerp Camp Pinnacle
Apr 9, 1947 Barbeau Sherwood Transcription service
Apr 21, 1947 Barbeau York Helderberg land owners
Apr 23, 1947 Barbeau York Studio location
Apr 21, 1947 Barbeau Rogers Camp Pinnacle
Apr 21, 1947 Barbeau Rousseau Helderberg land owner
Apr 21, 1947 Barbeau La Grange Helderberg land owner
Apr 21, 1947 Barbeau York WOKO
Apr 21, 1947 Barbeau Barron Transmitter site
Apr 23, 1947 Barbeau Rousseau Studio location
May 1, 1947 Barbeau York Rogers land
May 21, 1947 Barbeau York Rousseau land
May 29, 1947 Barbeau York Camp Pinnacle
May 29, 1947 Barbeau Watson Studio Floor plans
Jun 2, 1947 Barbeau York Rogers land
Jun 2, 1947 Barbeau Rogers Camp Pinnacle
Jun 10, 1947 Barbeau Velie (York) Camp Pinnacle
Jun 10, 1947 Barbeau Reed Camp Pinnacle
Jun 21, 1947 Barbeau Velie (York) Camp Pinnacle
Jun 23, 1947 Barbeau York Helderberg Land
Jun 27, 1947 Barbeau York Helderberg Land
Jul 3, 1947 Barbeau York Camp Pinnacle
Jul 5, 1947 Barbeau York Helderberg land
Jul 15, 1947 Barbeau York Schedule
Jul 23, 1947 Barbeau York Camp Pinnacle
Aug 11, 1947 Barbeau York Telephone facilities
Aug 14, 1947 Barbeau York Telephone facilities, STL, land surveyor
Aug 16, 1947 Barbeau York Land Survey, building location, costs
Aug 20, 1947 Barbeau York Land transfer
Aug 20, 1947 Barbeau Barron Transmitter building locations, FCC
Aug 25, 1947 Barbeau Rousseau Studio location
Aug 25, 1947 Barbeau Winslow Watson
Aug 29, 1947 Barbeau York Telephone service, STL
Sep 8, 1947 Barbeau York Pep talk
Sep 15, 1947 Barbeau York Land transfer, survey, Watson, studio location
Sep 20, 1947 Barbeau Barron Antenna type, mounting
Sep 23, 1947 Barbeau York Pep talk
Oct 4, 1947 Barbeau Linge Antenna mast
Oct 6, 1947 Barbeau York FCC STL
Oct 6, 1947 Barbeau York Call letter choice
Oct 7, 1947 Barbeau York Well drilling, politics
Oct 10,  1947 Barbeau Barron WBCA interference
Oct 14, 1947 Barbeau IDECO Tower
Oct 14, 1947 Barbeau Lehigh steel Tower
Oct 14, 1947 Barbeau Truscon Steel Tower
Oct 14, 1947 Barbeau American Bridge Tower
Oct 15, 1947 Barbeau York Scheduling
Oct 15, 1947 Barbeau York Building location, tower type, height
Oct 18, 1947 Barbeau York Antenna mounting
Oct 20, 1947 Barbeau York Access Road Location
Oct 23, 1947 Barbeau York Antenna location, scheduling
Oct 27, 1947 Barbeau York Land title, survey, well drilling, antenna height, FCC
Oct 28, 1947 Barbeau Torlish Well Drilling
Oct 30, 1947 Barbeau York Well Drilling
Oct 30, 1947 Barbeau Barron Antenna mounting
Nov 4, 1947 Barbeau York Scheduling
Nov 6, 1947 Barbeau Schenectady Steel Support mast
Nov 6, 1947 Barbeau Barron Antenna mounting, STL
Nov 5, 1947 Barbeau York WTRY construction progress (WTRI-FM)
Nov 6, 1947 Barbeau York Land survey
Nov 7, 1947 Barbeau Torlish Well drilling
Nov 17,, 1947 Barbeau York Progress report
Nov 17, 1947 Barbeau Barron Antenna mounting
Nov 17, 1947 Barbeau American Bridge Tower
Nov 26, 1947 Barbeau Barron Transmission line
Nov 29, 1947 Barbeau York Transmitter building design
Nov 2, 1947 Barbeau York Access road
Dec 3, 1947 Barbeau York Contractors
Dec 8, 1947 Barbeau York Contractors
Dec 9, 1947 Barbeau York Tower erection
Dec 9, 1947 Barbeau Zane Tower erection
Dec 9, 1947 Barbeau York Contractors, tower erection
Dec 11, 1947 Barbeau York Land clearing, building location
Dec 12, 1947 Barbeau York Land clearing, building location
Dec 14, 1947 Barbeau York Studio location
Dec 29, 1947 Barbeau York Construction start

This is a treasure trove of information on how this, and perhaps other early FM and TV stations went about finding land and building remote transmitter sites.  Remember that before this, AM transmitters could be placed in any convenient location with enough space for the tower and ground system.  The line of sight nature of VHF required high locations, which in the Northeastern US,  means prominent hills or mountains.  Sadly, this paper trail goes away in 1948.

Here are some of the highlights found in the letters above:

  • Washington DC consulting engineer for the project is John Barrons, who at one point suggests a different transmitter location closer to the city of Troy.  Barbeau insists that the Helderberg location is best because the GE engineers chose it for their FM and TV experiments.
  • Negotiations with several land owners along the edge of the Helderberg escarpment are finally successful, with a 10 acre parcel of land purchased from Mr. La Grange, noted as being across Camp Pinnacle Road to the south of the WBCA transmitter and adjacent to the west of the GE parcel, cost $2,000.  From this, I surmise the former WBCA site stood where the former WHMT site stands today.
  • Land survey completed by Mr. J. Kempf of Albany.
  • The FCC application is completed with new transmitter location, antenna height and frequency of 92.5 MHz.
  • At one point, Barbeau tried to hire Walter Watson, an RPI architecture student, to draw up the studio floor plan, paying him $15.00.  At first Watson agrees, then backs out of the deal.  Frank York hires an architect to draw the studio floor plan and the transmitter site building plan.
  • Once the plot of land for the transmitter site is purchased, several different building locations and antenna configurations are discussed.  It is noted that both WBCA’s and WGFM’s original antenna was mounted on a pole at ground level.  The later station was moved to a makeshift tower.
  • WBCA management raises concern with the FCC about potential interference from the new station’s transmitter and potential STL, noted as an S-T link.
  • In September of 1947, Frank York expresses some concern with viability of project, Barbeau sends several “pep talk” letters saying that FM radio is the future of broadcasting.
  • The building site is chosen, land cleared, access road installed, work done by Orsini Brothers Construction from Altamont, clearing and road work cost $2,000.
  • The call letters WFLY are chosen, they are the initials of Frank Lloyd York.
  • An 80 foot Blaw-Knox self supporting tower is purchased and installed by Zane Construction, cost of tower is $1,700 installation was another $200.00.
  • Well is drilled by Stewart Brothers well drilling from Guilderland, cost of $5.90 per foot drilled, total cost unknown.
  • Transmitter building work began, building is noted as a two story, concrete block construction, work done by Orsini Brothers.
  • A GE BY-4-C four bay circularly horizontally polarized antenna and 3 1/2 inch Andrew transmission line is installed on tower.
  • Building construction progresses, telephone and electric service installed.  Three phase electrical service cost $2,100 from New York Power and Light.
  • Studio site chosen in at the Troy Hotel in downtown Troy.
  • Living quarters constructed on second floor of building for full time transmitter engineer.
  • A GE BF-3A 3 KW FM transmitter purchased and shipped.
  • Building construction completed.
  • Transmitter installed and tested.
  • Telephone circuits between new studio installed and tested.

The transmitter site construction was finished in the spring of 1948.  The studios were completed in late July of 1948 and the station signed on the air on August 18, 1948.  This is the transmitter site that they ended up with. as it looks in 2007:

WFLY transmitter building, circa 2012

WFLY transmitter building, circa 2007

In addition to the construction, there was quite a bit difficulty from the WBCA management, who were concerned about possible interference.  WBCA was part of the “Continental Network” and received most of it’s network programing via direct over the air relay from W2XMN/W31NY, 43.1 MHz, in Alpine, NJ.  They complained to the FCC about potential interference on both their over air network relay (43.1 MHz) and the Studio to Transmitter Link from downtown Schenectady on 950 MHz.  In the end, the FCC was unimpressed with these arguments and granted WFLY its operating license.

The transmitter building was made twice as large as needed because the Record had plans to launch a TV station.  In addition to this, there were complete living quarters on the second floor which included a bathroom, shower, kitchen, bedroom and large living room area.  This was in the era before remote controlling of transmitters was permitted by the FCC.  It took a hardy soul to live at the remote transmitter site full time.  Even today, it is far outside of town and can be difficult to get to in the winter time

These mountain top transmitter sites did not exist prior to the advent of TV and FM.  The amount of planing and work went into launching this station is quite impressive. For the early FM radio stations, this type of effort and expense was probably typical.

The Shively Branched combiner

Did some work a while ago at a transmitter site that had three transmitter combined into one antenna.  The site uses a Shively branched combiner:

Shively Branched combiner

Shively Branched combiner

Each transmitter can be tested into a separate 20 KW dummy load:

Three inch coax switches

Three inch coax switches

Transmitter themselves are Nautel NV15s:

Nautel NV20 transmiters

Nautel NV15 transmiters

Except the one on the end, which is an older BE FM20A.

Series surge suppressor

Radio facilities, particularly mountain top transmitter sites, are prone to power transients. The causes can be varied, but most often, lightning is the culprit.  Long power transmission lines to the site are vulnerable to direct strikes and EMF induced spikes from nearby strikes.  Other issues, such as switching transients, load fluctuations, and malfunctioning equipment can lead “clear weather” outages.  Of course, the best way to deal with such things is prevention.

Power line surge suppressors have been around for quite some time.  They usually take the form of a MOV (Metal Oxide Varistor) connected between the hot leg and neutral or ground.  There are a few differences in designs, however.  Typically, most facilities employ a parallel surge suppressor.  That normally take to form of an enclosure hung next to the main power panel with a group of MOV modules in it.  The MOVs are feed from a circuit breaker in the panel.  Like this:

LEA parallel surge suppressor

LEA parallel or shunt surge suppressor

This is an LEA three phase 208 volt shunt surge suppression unit, which has MOVs between all phases to ground and each other.  That is connected in parallel to the electrical service with the circuit breaker disconnect.  These function well enough, provided there is a good bit of series inductance before the unit and also, preferably after.  The series inductance can come from many sources, including long secondary leads from the utility company transformer or electrical conductors enclosed in metal conduit, particularly rigid (verses EMT, or FMC) metal conduit.  The inductance adds a bit of resistance to the transient voltages, which come in higher than 50 or 60 Hz AC waveform.

A better method of transient protection is the Series Surge Suppressor.  These units are installed in line with the incoming service and include an inductor to add the required series resistance coupled with MOVs and capacitors.  Most series surge suppressor also filter out harmonics and RF by design, something desirable particularly at a transmitter site.  Series surge suppressors look like this:

LEA DYNA systems series surge protector

LEA DYNA systems series surge protector

This is a LEA three phase 240 volt unit.  As in the other example, all phases have MOVs to neutral and each other.   There are MOVs and capacitors on the line and load side of this unit (line side is the bottom of the inductor).  A basic schematic looks like this:

Series surge suppressor basic schematic

Series surge suppressor basic schematic

A few things to note; MOVs have a short circuit failure mode and must be fused to protect the incoming line from shorts to ground.  MOVs also deteriorate with age, the more they fire, the lower the breakdown voltage becomes.  Eventually, the will begin to conduct current at all times and heat up, thus they should also be thermally fused.  MOVs that are not properly protected from over current or over temperature conditions have the alarming capacity to explode and/or catch on fire.  From experience, this is something to be avoided.  Matched MOVs can be paralleled to increase current handling capacity.

The inductor is in the 100 µH range, which adds almost no inductive reactance at 60 Hz.  However, it becomes more resistive as the frequency goes up.  Most transients, especially lightning, happen at many times the 60 Hz fundamental frequency used in power distribution (50 Hz elsewhere unless airborne, then it may be 400 Hz).

Capacitors are in the 1-10 mF range and rated for 1 KV or greater as a safety factor.  The net effect of adding capacitance is to create a low pass filter.  Hypothetically speaking, of course, playing around with the capacitance values may net a better lowpass filter.  For example, at 100 uH and 5 mF, the cutoff frequency is 225 Hz, or below the fourth harmonic.  Care must be taken not to affect or distort the 60 Hz wave form or all sorts of bad things will happen, especially to switching power supplies.

These units also need have a bypass method installed.  If one of the MOV modules needs to be replaced, power to the unit has to be secured.  This can be done by connecting it to the AC mains before any generator transfer switch.  That way, the main power can be secured and the site can run on generator power while the maintenance on the surge suppression unit is taking place.

Restarting a Harris HT35 FM transmitter

This transmitter was retuned from 107.9 to 92.9 and put back into service. Retuning an HT35 transmitter is no small matter, there are 32 pages of retune instructions.  This unit is now in service as the main transmitter for WEZF, Burlington, VT.

The transmitter power output is 22,000 watts into a four bay, three around panel antenna, which gives it an ERP of 46,000 Watts at a height of 824 meters (2,703 feet) above average terrain. The tower is at the summit of Mt. Mansfield, which is 1,340 meters (4,395 feet) above sea level.

Mount Mansfield TV and FM antennas

Mount Mansfield TV and FM antennas

This is the Mt. Mansfield FM transmitter room. There are two TV stations in this building as well.

Final frames are of the WVPS Nautel NV-40 transmitter.

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