FM transmitter site – Page 5 – Engineering Radio

Shipping Container transmitter site

I do not particularly like these. I know, they are relatively inexpensive, easy to come by, easy to install, etc. However, a shipping container was not designed to house a transmitter, they have certain drawbacks. These are, in no particular order:

Air conditioning. Using a traditional Bard-type equipment shelter HVAC unit requires cutting through a lot of fairly heavy gauge steel. What’s more, the steel walls are uneven, requiring a filler.
They are by necessity, fairly narrow. Arranging racks and transmitters along the length of the unit restricts access to either the front or the back of the equipment. Meeting NEC clearance requirements for electrical panels, transfer switches, and disconnects can pose problems.
They are not very tall. Mounting overhead equipment can be problematic as one does not want to drill through the top of the container. Crosswise unistrut is one solution, but it lowers the overhead considerably.
Electrical work is slightly more dangerous. Doing any kind of electrical work, troubleshooting, repairs, etc is a little more nerve-racking when everywhere around you is a metal surface at ground potential.
They are difficult to insulate against cold and heat.
The door-latching mechanisms bind, wear out or otherwise fail over time.

All of those things being said, I am now rebuilding a transmitter site in one of these shipping containers.

Inside view of shipping container transmitter site

Fortunately, the original electrical work was not bad. The transmitter is a twenty-year-old BE FM10B, which will be retained as a backup. The new transmitter is a Gates Air FAX-10. We have installed several of these Gates Air transmitters in the last two years or so and they seem to be pretty solid units. This is the second 10KW unit I have installed.

Gatesair FAX-10 transmitter in Middle Atlantic Rack

We decided to install the FAX-10 in a Middle Atlantic rack since we did not have a whole bunch of extra room for a separate transmitter rack. The 1 5/8 inch coax switch is installed in the top of the transmitter rack along with a Tunwall TRC-1 switch control unit. The other rack will have the STL and all other ancillary gear. My idea is to have nothing in between the door and the FM10B so it can be easily removed when that day comes. Something, something about planning ahead since it will be likely myself removing the FM10B.

A Linux based remote control system

We are extending LANs out to transmitter sites for many reasons; backup audio, control and monitoring, security systems, VOIP phones, etc.

I am casually (very casually) toying around with creating my own Linux-based remote control system. The ongoing Windows 10 upgrade debacle continues to not end, I can’t help but think that there are many potential clients who could use a reliable transmitter/studio remote control and monitoring system based on a stable operating system. Hmm, sounds like a sales pitch 😉

Anyway, I have run across several Ethernet board manufacturers that offer a variety of boards with 8-12 contact closures and a variety of analog and digital inputs. Most new transmitters have some sort of web GUI which are great for transmitter control and monitoring. As we all know, there is more than just a transmitter at any given transmitter site. In addition to the transmitter, I would like to control and monitor things like tower lights, interface and control of coax switches, temperature monitoring, generator status, the old non-web interface backup transmitters, STL signal strength for those old 950 MHz links, etc.

Since Google is my friend (when they are not storing my search data), I came up with this: Internet-ethernet-12-channel-relay-board

That particular PC board is made in Bulgaria, which is home to this: Mount Buzludzha

What I like about these particular boards is the DRM software (DRM has, apparently, many different meanings) which will run on Linux or Windows. There are also iOS and Android applications that can be used as well. It appears that the GUI can be customized for various uses. This seems like it is written in Java, so perhaps I could have some Java expert customize it for radio use. It looks like up to 32 boards can be controlled by a single instance of the DRM software. Alarm reporting would be via SNMP trap and email.

I don’t know, there is one particular cluster of stations that needs new remote control gear at almost every transmitter site. Perhaps a little alpha testing is in order? It could be fun…

Anyway, just a thought…

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 (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:

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. Their stuff is in the open-frame racks to the right of WNNI.

Another view:

Transmitter racks for WUPE-FM, WNNI and W266AW

TL;DR: Tower collapses, and the facility is rebuilt better than before.

Be careful where you put your hands!

So, I was working at one of our FM clients in Albany when I decided I had a few moments of spare time, so I could neaten up the remote control rack. I opened the rack door and was staring intently at the remote control interface panel when out of the corner of my eye, I saw something move.

Now, the top of the rack is a little bit dark and I was not sure what I was looking at. At first, I thought somebody had stuffed a rag in the top of the rack. But, I could not figure out why anyone would do such a thing. Then I thought it was some cardboard. I almost reached up and grabbed it, but something was amiss. Then I saw the tough flick out and smell the air:

At this point, I think I may have said something like “Oh, shit!” and took several steps back. Those colors and patterns have two possibilities; Copperhead or Grey ratsnake. Since I could not really get a good look at its head, I could not tell which it was. I went and got a work light to see better with.

A copperhead is a pit viper, which has a triangular-shaped head and a small indentation or pit under each eye. This snake has neither, so it is fairly harmless. Actually, the rat snakes are beneficial because they eat the mice and other pests around the transmitter building. There are several versions of these in the northeast, including a black rat snake which happens to look just like a piece of 7/8 coax laying across the pathway to the door, until it moves that is…

This species can get to be about 6 feet long (1.8 meters) and the larger ones can draw blood when they bite. Even though he looked to be on the small side (approximately 30 inches or 76 cm), I decided that discretion is the better part of valor, closed the door on the rack, and did something else for a while.