When putting together a remote control system, we are inevitably confronted by the differing control and monitoring needs of each piece of equipment within a station. The main transmitter may require a momentary closure to ground, whereas the auxiliary requires latching a voltage. The Common Point sample exceeds the input level of the remote control during the day but not at night. When all is said and done, many of us find ourselves with a combination of relay interfaces, voltage dividers, operational amplifiers and a variety of other extras required to properly interface the remote control system, filling up rack space and adding additional problems and maintenance concerns. The need to issue alarms for time dependent systems, such as tower light monitoring and day/night common point readings, and the desire to avoid persistent alarms for momentary excursions from the norm, such as silence sensing, just add to the problems.
Rick Prime, technical director for Family Stations, recently sent me the Easi-8 remote control unit developed by Wit. At first glance, I noticed the size and simplicity of the unit. At 3" × 8" × 6" the unit is small — small enough that two can be mounted side-by-side in a 19" rack. The package contains a panel for mounting the system in a rack, and a dual panel is available. Mounting brackets are also included for wall mounting the unit. The front panel contains a series of LEDs and looks like a large network router. The rear panel offers 18 Phoenix plug receptacles and an RJ-45 jack. The unit is a network-based remote control system with flexibility in the metering inputs, control outputs, limit monitoring and logging.
Metering and control
Each input channel uses a fully balanced difference amplifier requiring no reference to ground. Input voltages can be ac or dc of either polarity, with a range from zero to 160V.
Relay contacts on the control outputs are rated for 2A at 24Vdc, 50W max switched load, or 1A at 120Vac, 120VA max switched resistive load. Each relay output can be configured with isolated set and clear closures, or configured as a full Form C with the typical NO-C-NC connections.
Now it gets really good. Plug it into a computer network, point a browser to it and now you have a wide range of programming and configuration options.
Performance at a glance
Small and lightweight
Flexible monitoring inputs and control outputs
Versatile logging options
Each metering input can be calibrated by entering offset and multiplier values. Or, it can be calibrated by connecting the sample, entering what the meter should display and the values are calculated for you. Setting alarm conditions is one of the real shining points of this unit. Four limit values can be established for each input. Separate actions can be taken for each limit, as well as separate actions taken as the value goes above or below the limit. The actions taken consist of logging, e-mailing, executing a relay closure or nothing. A time delay can be applied to that limit so that an alarm condition exists only if the limit is exceeded for a specified period of time.
Tower light monitoring provides a good example. By feeding the output of my ac tower light current sample into the unit, I can set a low limit to log the time when the lights turn on and off. I set another limit to send a notification if one sidelight is out, a third limit to send a notification if the beacon is not blinking, and a fourth limit to send a notification if the beacon is stuck in the on position. All these limits can have time conditions applied to them so it won't trigger an alarm in the daytime. A similar approach could be used for different day and night common point values and tower parameters.
The default display provides all the channels for a single unit on one browser page. When using multiple units, the screens for each unit can be displayed by clicking through the Windows task bar. Alternately, specific pages may be defined by pulling readings from any input of any unit within the network. I have three pages setup: one displays transmitter, tower lights and general info, a second displays the day antenna values and day common point, and the third displays night antenna values and night common point. The metering display provides numerical and graphical representations of the metering input. On a 17” LCD monitor, I could easily watch all of the tower values at once, from across the room, while making phasor adjustments.
User screens can be customized to display readings from all the Easi-8 units in use.
Network-based communications provide a variety of configuration options. A unit can be plugged into a cable or DSL network with a static IP, and monitoring can be done from anywhere with Internet access. Prior to obtaining a high-speed connection, I connected mine to a network with a Windows XP machine acting as a host for Windows Remote Desktop. I could then dial in and view the system. This is slow but sufficient.
All the extras
Included with each unit are a rack panel, wall brackets, a prewired temperature sensor ready for use, power supply, Phoenix plugs for the input and output connections, a direct and a crossover Ethernet cable, a little greenie screwdriver, installation manual and a current version of Java on CD. The installation manual provides the basic features of the Easi-8 to help you get started. Actually, a quick read-through was all it took. Much of the setup was done intuitively. However, if needed, a more detailed manual is provided on the included CD.
I've always felt that consistent logging of readings, particularly at a directional AM, was one of the best diagnostic tools I have to intercept problems in the antenna system. A slow drift over time or rapid changes in the first few minutes of energizing an ATU can aid in diagnosing a failing capacitor or other problems. The logging functions of the Easi-8 are versatile. The unit can be programmed to e-mail a log that consists of a snapshot of readings. The frequency of e-mails can range from once every second to once a day or less. It could also be programmed to e-mail only on an alarm. As an aside, during testing, it takes about 1.5 seconds to send the e-mail so you only get about 40 messages in a minute if it's set to log every second.
While on the subject of diagnostic tools, I believe this unit would be a useful addition to the toolbox. The small, lightweight box can easily be deployed at any location to log power line fluctuations, control timing or anything else that can be monitored via a voltage or contact closure.
Technical support and development are intertwined with Wit. Minor bugs in the system were identified and solved. Suggestions made were considered and in some cases implemented. In fact, if I do have a complaint, it is that the documentation lags behind the constant improvements and features being added. However, this is a minor complaint because I am pleased with the initial features and any questions are only a phone call away.
Versatility, size and simplicity are the most desirable factors in this device. Wit has determined what the real-world concerns are for the station engineer and have produced a product that addresses those concerns agressively and effectively.
Zimmer is assistant technical director of KECR, Lakeside, CA.
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