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.