North Adams tower update III

And final.

It has been a year and a half since the tower collapse in North Adams, Massachusetts.  Since that time, WUPE-FM (Gamma Broadcasting), WNNI and W266AW (New England Public Radio) have been operating with STAs at lower than licensed power.   We have completed the installation of the combined antenna, filters and combiners and now all stations are back to full power.  Here are a few pictures of the transmitter room:

WUPE-FM and WNNI transmitter racks, North Adams, MA
WUPE-FM and WNNI transmitter racks, North Adams, MA

WUPE-FM (left hand rack) is using a Crown FM-2000 transmitter, loafing along at 1,060 watts. WNNI (right hand rack) is using a Gates Air Flexiva 2 running at 1,650 watts. Those stations are combined with a Shively Combiner:

Shively combiner
Shively 2 way star junction combiner

We are still doing some grounding and neatening work behind the racks:

Behind racks
Behind racks

The Shively versa tune antennas that were mounted to the wooden utility pole as emergency antennas will be retained as backup antennas for both stations.

Transmitters for WUPE, WNNI and W266AW
Transmitters for WUPE, WNNI and W266AW

We share the room with Access Plus, which is a wireless internet service provider in western Massachusetts. There stuff is in the open frame racks to the right of WNNI.

Another view:

Transmitter racks for WUPE-FM, WNNI and W266AW
Transmitter racks for WUPE-FM, WNNI and W266AW

TL;DR: Tower collaspes, facility is rebuilt better than before.

Meltdown

After one of our clients had an FM station go off the air over the weekend, I investigated and found this:

Transformer melt down
Transformer melt down

Looks like something one might find in the reactor room at Chernobyl or Fukushima.

Transformer melted down
Transformer melted down

This is at one of those sites with three phase open delta power.  Needless to say, the transformer is toast, perhaps the entire transmitter too.  This will be another fun transmitter scrapping project.  I was thinking about this; over the last five years, I have scrapped at least ten to fifteen old tube transmitters.  The old tube types are going away fast, as are those that can still work on them.

The side mounted FM antenna

In an interesting development, the FCC has taken notice of some pattern distortion from the side mounted FM antenna of KFWR, Jacksboro, Texas.  For those, like myself, not familiar with Texas Radio, that is in the Dallas/Fort Worth market.  The crux of the issue is co-channel interference to KCKL in Malakoff, Texas.  These two locations meet the spacing requirements in 73.207 (215 km).  The issue is with the side mounted ERI antenna and what appears to be intentional pattern optimization.

From the FCC order to show cause:

ERI’s president, Mr. Thomas Silliman, acknowledging that KFWR’s antenna “was mounted in a favorable direction, but… has not been directionalized and therefore is legal.” Mr. Silliman adds that the custom lambda tower at the top of the new KFWR tower was specifically designed for operation at KFWR’s frequency of 95.9 MHz, and that the tower’s lattice structure is “repetitive at the half wave of the specified FM frequency.” Thus, “if one picks a favorable mounting position on the tower, every element in the array sees the same favorable mounting result. Mr. Silliman also states that vertical parasitic elements are used to make the vertical radiation pattern “more circular” and reduce the vertically polarized gain to the east. In a subsequent pleading, ERI elaborates that its computed values “are relative to an RMS measured field of 1.0.” Mr. Silliman concedes that the mounting of the antenna on a certain tower face constitutes “pattern optimization,”arguing later that this is a common practice used by all antenna manufacturers, but states that it is the ERI’s policy “not [to] increase the directivity of the antenna pattern.”

The FCC concludes that the directionality of the side mounted antenna, in this case, is clearly intentional. The radiated power towards co-channel KCKL was calculated to be 274.5 KW, which is in excess of the 100 KW limit and orders KFWR to reduced TPO from 25 KW to 9.1 KW.

We have lots of these out in the field:

Side-mounted Shively 6810 antenna.  WSPK, Mount Beacon, NY
Side-mounted Shively 6810 antenna. WSPK, Mount Beacon, NY

In fact, I believe the majority of our FM stations use side mounted antennas.  Some of them are mounted to a leg and some are mounted to a face.  Usually, I try to place the antenna on the tower so that the bays are facing the desired audience.  This information is given to the manufacture when ordering the antenna so that proper mounts can be furnished and the mounting distance between the tower and antenna properly calculated.  That is about the extent of any “optimization” that is allowed.

As the FM band gets jam packed with FM signals, this may become more of an issue in the future, particularly around dense signal areas around major metropolitan areas.

Transmitter site re-hab

One of the reasons for the recent lack of posts; I have been busy rehabilitating several transmitter sites for various broadcasting companies. These are mostly FM transmitter sites and vary in power from one kilowatt to twenty six kilowatts ERP.  I enjoy project work, but I have been driving hither and yon, racking up 27,000 miles on my new car since last August.

Subaru Crosstrek XV at remote transmitter site, somewhere in rural New York
Subaru Crosstrek XV at remote transmitter site, somewhere in rural New York

So, here is one transmitter site that I just finished; WFLY, Albany, New York.  Removed Collins 831F2 transmitter which was functioning as a backup and installed new Broadcast Electronics FM20S.  The Continental 816R2 is becoming a little bit long in the tooth for a main transmitter, being new in 1986.  Thus, it was time to install a new unit, and I like the Broadcast Electronics solid state and tube designs.  With the BE AM and FM solid state units, their simplicity is their beauty.  We service many BE transmitters, some are thirty years old and are still supported by the manufacturer.

WFLY transmitter building, New Scotland, NY
WFLY transmitter building, New Scotland, NY

The BE FM20S transmitter is actually two FM10S cabinets combined with one controller.  Each cabinet requires a 100 amp three phase mains connection.  This station’s TPO is 11.5 KW, so there is plenty of head room in case the owner’s ever want to install HD Radio or replace the three bay antenna with a two bay unit.

WFLY main transmitter, Broadcast Electronics FM20S
WFLY main transmitter, Broadcast Electronics FM20S

In transmitter cabinet two, above the exciter is room for HD equipment.

BE FM20S exciter housing
BE FM20S exciter housing

I also reworked the coax switches to provide easier implementation of the backup transmitter.  Basically, the main transmitter is on the main antenna, the backup transmitter is on the backup antenna.  We can move the second coax switch to test the backup into the dummy load.  We can move the first coax switch to change antenna feeds.

WFLY backup and main transmitters
WFLY backup and main transmitters

Pretty standard setup.

WFLY RF path diagram
WFLY RF path diagram

We moved the Collins 831F2 from Albany to here to replace another, dead Collins unit at WKXZ in Norwich, New York.  This transmitter is forty years old, but still runs reliably.  Of course, doing this work in the dead of winter added a degree of difficulty to the job, as the roads to both the WFLY and the WKXZ transmitter sites needed work to make them passable for a moving truck.  In the end, we used a skid steer with forks on it to get the transmitter up the final hill and into the small WKXZ transmitter building.

Collins 831F2 transmitter, WKXZ, Norwich NY
Collins 831F2 transmitter, WKXZ, Norwich NY
Collins 831F2 transmitter
Collins 831F2 transmitter

The WKXZ transmitter building interior is floor space challenged. It is located next to a former TELCO microwave site which has a guyed tower.