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The Very Long Baseline Array

The Very Long Baseline Array (VLBA) is a network of antennas spread across the United States and operating as a single telescope.

This page details the station located near Brewster, WA. The 10 stations are almost identical.

The Brewster VLBA station is located in North Central Washington State, near the Okanogan River. The antenna is located next to a couple of orchards and a hay field.

Brewster VLBA station from the south

The antenna is in a remote location to minimize the RF interference from electronic devices.

Sign near Brewster VLBA

The area was selected due to being one of the dryer parts of Washington State. However, there is still snow every year.

View of Brewster VLBA antenna
Brewster VLBA antenna from behind

View from the top

The top of the antenna provides a nice view of the area.

Train from top of antenna.

There is a small building which houses the computers, support electronics, and a couple station techs.

View of Brewster VLBA office from antenna

Looking south from the edge of the dish over the nearby apple orchards.. The gray line is a lightning rod.

View from antenna to the south.

Working on the FRM

The focus rotation module (FRM) allows the antenna to focus the beam on a specific receiver. Thankfully it does not need much maintenance, as it is a cold and windy place in the winter.

Working on the Brewster VLBA FRM

Bird nest

Birds often nest on the antenna. Smaller birds generally do not cause any problems. However, pidgins must be evicted due to the mess they make.

Bird nest at Brewster VLBA station

Hawk on Weather Station

Each station is outfitted with a weather station. It allows the scientists to monitor the atmospheric conditions at the time of an observation. It also provides for automatic antenna stow in case of a high wind.

Because the hawk was interfering with wind direction readings some roosting prevention measures had to be taken. The hawk now roosts on the nearby trees, or on the orchardist's wind machines.

Weather station circuitry.

This is part of the original weather station from construction of the VLBA. With some maintenance, this station has been in operation for over 20 years. While newer weather stations are available, the cost of verifying and integrating new units is currently higher than the cost of maintaining the old unit.

VLBA weather station circuitry.

Snow on the antenna

A light snowfall stuck to the antenna, and then melted in the areas where the panels are reinforced

Snow stuck to the antenna

Many parts of the antenna were custom built for the VLBA. But sometimes a cost effective solution can be found using off the shelf parts. Here a drip tray was made form a $3 pizza pan and some white paint.

Station tech installing a drip tray

Burnt motor brush

Whenever there is a problem the station technicians have to respond quickly in order to minimize the antenna down time. As can be seen here, the wire powering the motor brush is burnt. Fortunately, a supply of these is kept on hand. Unfortunately, this was not the only problem.

Photo of burnt brush.

What was left of the brake pad

As can be seen here, the brake pad was also destroyed. Spare pads are also kept on hand, but in cases like this it is important to find the root cause of the problem.

Photo of demolished brake pad

El drive motor field coils

There was also damage to the drive motor itself. To repair the antenna as quickly as possible the entire motor was replaced with a spare. The old one was then shipped back to the servo shop to be rebuilt.

Motor field coils

Armature from the El drive motor

There is some damage to the armature. When the motor is rebuilt the coils on the armature will be replaced as needed. The commutator will also be resurfaced. Once the rebuilt motor is ready it becomes the new spare.

Armature from motor

Nice sunset. Or is that a sunrise?

Brewster VLBA station at sunrise

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© David C. Hunter, 2014
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