The PIROD PRLC-A tower lighting controller

PIROD tower company has been around for a while, thus there are likely many of these tower light controllers out in the field.  They perform a vital service in controlling and monitoring tower lights at remote transmitter sites maintaining a safe operating environment for aircraft and compliance with FCC rules.

PIROD was sold to Valmont in 2004, Valmont no longer manufactures or supports the product.  All is not lost, however, as XCEL Tower Controls does support it and parts are still available through them.

These units were fairly rugged, had good surge suppression on the incoming AC lines and are designed for easy access to service parts.

PIROD PRLCA tower light controller, WRKI Brookfield, CT
PIROD PRLCA tower light controller, WRKI Brookfield, CT

This particular controller is being installed at WRKI in Brookfield, CT.  We are adding toroid cores to the tower lighting circuits coming off of the tower because the last controller has been mostly destroyed by lightning.  It is a tall tower, on top of a tall hill, thus it gets struck by lightning many times over the course of a year.

WRKI tower, Brookfield, CT
WRKI tower, Brookfield, CT

The block diagram looks like this:

PIROD PRLCA block diagram
PIROD PRLCA block diagram

Click for higher resolution.

The basic schematic looks like this:

PRCLA tower light controller schematic
PRCLA tower light controller schematic

Click for higher resolution.

The entire manual can be found here, (medium sized .pdf) courtesy of John Brickley of EXEL tower controllers.

The Rabbit Hole

The internet is a wonderful technical achievement. It has truly changed the course of human history in ways incalculable. The amount of information available to anyone with access is simply astounding.  Then there is this:

Demotivator
Demotivator

I am supposed to be doing research for my technical writing class, but I keep getting sucked back in. Some of these are quite funny:

Demotivator
Demotivator

GAH! Someday, if I could figure out how to get that cloaking device to work, I would like to seek into all those conference rooms and replace the standard issue motivational poster with this one:

Standard issue demotivator
Standard issue demotivator

And the minutes still tick by, with my paper undone.  These are from despair.com,

Demotivator
Demotivator

The professor is going to have my butt.

It has been relatively light blogging these last few weeks, for several reasons; some of them obvious, some of them not so much.

WVTQ Mount Equinox, Vermont

The transmitter for Vermont Public Radio, WVTQ 95.1Sudbury is located on Mount Equinox, near Manchester Vermont.  Mount Equinox is one of the better mountain top transmitter sites to get to as it has a good access road, no jeep trails through the woods or ski lifts, etc.  The Summit is 3,580 feet (1,175 m), which is the third highest peak in the green mountains.  On a nice day, the view from the top is spectacular:

South view, Mount Equinox, Vermont
South view, Mount Equinox, Vermont

The southern view with US Route 7 cutting through the valley below.

WVTQ is a part of VPR’s classical music network.  They had a Nautel VS-1000 that had developed issues with the directional coupler.  This unit was repaired and re-installed:

WVTQ Nautel VS-1000 transmitter, Mount Equinox, Vermont
WVTQ Nautel VS-1000 transmitter, Mount Equinox, Vermont

The transmitter has a 7/8 EIA flange on the back, which had an elbow, then an adapter to a type N connector all unsupported. My boss felt that perhaps that perhaps too much weight on the EIA flange caused the crack in the directional coupler.

WVTQ transmitter racks and STL equipment
WVTQ transmitter racks and STL equipment

The transmitter site used to be in the basement of the hotel, but as that building no longer exists, it was moved over to the former RADAR site.  The RADAR site consists of four 80 foot towers arranged in a square around a building.  These towers now support two way radio equipment and the like

WVTQ transmitter site, Mount Equinox, Vermont
WVTQ transmitter site, Mount Equinox, Vermont
Finer points of GPS antennas
Finer points of GPS antennas

Your author (left) with Rich Parker of VPR discussing the finer points of GPS antennas.

Stairway to heaven
Stairway to heaven

Ladder to the top of one of the towers.

Hang Glider's view, east side pulloff, Mount Equinox, Vermont
Hang Glider's view, east side pulloff, Mount Equinox, Vermont

View from the turn off on the east side of Skyline Drive.  Known as “hang glider’s view” with good reason.  This is on the saddle that connects little Equinox with big Equinox.

On a nice day, such as yesterday, it is very pleasant.  When the road is covered in ice and snow, not so much.

The XDS satellite receiver

I remember, back in the day, when we all used Scientific Atlanta 7300 satellite receivers. There were two flavors of decoder cards; DATS and SEDAT.  Starting about 1982 or so, satellite distribution of network audio was a quantum leap over the old TELCO circuits used previously.  The use of satellite downlinks allowed radio stations to receive an almost unlimited number of programs from every network under the sun.

The SA 7300 receivers gradually gave way to the SA 3640, which gave way to the Starguide, Starguide II and Starguide III series which finally lead to the XDS and MAX receivers used today.

XDS satellite receivers
XDS satellite receivers

The newest generation satellite receivers are yet another quantum leap over the last, with on board hard drive storage that allows time shifting of entire shows.  Another nice thing is the web interface.  Before you know it, everything in the broadcast plant will have a web interface.

The one issue I have had with nearly every single XDS receiver is the fan going bad.  The manufacture must have laid into a supply of defective fans.  A bad fan is noted with the fault light turns red and the unit will return a “Fan stopped” error message.  The network will send a replacement fan if you let them know.  I have carefully replaced several of these fans without turning the receiver off.

Otherwise, the web interface is pretty intuitive.  Drop down menus allow for programming the audio ports on the receiver and setting up the delayed recording and playback function.

XDS satellite receiver weekly programming grid
XDS satellite receiver weekly programming grid

Any required network closures are configured in the relay screen.  The programming clock provided by the network will specify which relays are used for each show.

XDS relay maping screen
XDS relay maping screen

Each receiver has two DB-37 connectors that have 16 relays each for a total of 32 output closures.  That should be enough to cover almost any programming situation.

Finally, the receiver’s overall operating condition can be monitored via the health screen:

XDS satellite receiver health screen
XDS satellite receiver health screen

Something like this can greatly speed up any remote diagnostic trouble shooting by eliminating (or pinpointing) a satellite system failure as the reason for a station being off the air.  I also make sure that all automation systems have some type of remote access like VNC so that I don’t have to needlessly drive to the studio to fix a silly computer problem.

Then there is one more neat tool, for those XDS receivers that do not have any front panel user controls (one certain network uses these), called the “XDS discovery tool.”  I have found this bit of software to be very helpful from time to time.