The Mt. Diablo Amateur Radio Club (MDARC) Communications Trailer has been a part of the MDARC vehicle fleet for many years. Up until a couple of years ago, it had become a repository for Field Day equipment year-round, looking like a storage locker on wheels.

In 2017, a Trailer Committee was formed to rehabilitate the trailer into a mobile communication center, and a training and outreach vehicle. A complete inventory of the contents of the trailer was made. All non-essential items were moved out of the trailer. Drawings were produced showing the planned utility outlets for each operating position within the trailer.

A complete utility interface system is furnished in the trailer at each of the four (4) operating positions, including: 120-volt 20-amp AC power, 13.8-volt DC power via PowerPole connections, coax routing for the antennas (HF connectors), a complete grounding system, 2.1 amp USB charging ports, and auxiliary plug-in speakers. A solar trickle-charging system keeps the on-board battery topped off at maximum voltage, guaranteeing immediate deployment.

MDARC Trailer Operating Position #4

Mobile communications would include HF, VHF and UHF communications for public service events, emergency communications drills and communications when a real emergency hits the Bay Area.

Communications would be implemented by operators bringing to the trailer their own rigs and any antennas which they choose to use. Operators would be able to mount their antennas on one of the fixed masts at the front of the trailer, or on the crank-up mast at the rear of the trailer. Multiple lengths of LM 400 coaxial cable are in permanent inventory, up to 50 feet in length.

For HF work, a beam could be mounted on the 30-foot crank-up mast at the rear of the trailer, or an appropriate dipole wire antenna could be used, or the Club provided HF vertical antenna that is part of the trailer permanent inventory could be used.

For digital modes, operators will bring their own radios and laptop computers. Three Dell desktop monitors, a 32-inch Color LED Monitor and a 42-inch color LED Monitor are available to expand and/or duplicate laptop screens. Video is distributed via an HDMI to DVI-D hub. Various VGA/HDMI adapters are available.

The trailer utilities are described above. Lighting, heat and air conditioning are supplied for the operators. An umbilical cable is available to allow the operators to set up an operating position outside of the trailer for educational or demonstration purposes. Generator power, or shore power from a utility, would be connected to the trailer AC power system through the shore power connection. A 50-foot 10-3 shore power cable is part of the permanent inventory. With shore power connected, all DC operation can be accomplished through the use of the permanent Astron RS-50M 13.8-volt 50-amp Power Supply. When shore power is not available, a three (3) panel,100-watt solar array (stored on-board) with charge controller will keep the on-board battery charged.   Also, a 2200-watt inverter generator is in permanent inventory in the trailer for use when shore power is not available.

Girl Scout Sophie and Cub Scout Pete get instructions before “Getting On the Air" 

As a training and outreach vehicle, the trailer will be used for training Scouts to meet their merit badge requirements, and at local school STEM and STEAM events (Science, Technology, Engineering, (Arts) and Mathematics). Benches will be located in the trailer where the students could watch one of the two video screens comfortably. For public outreach activities, such as the annual Field Day, the trailer would be set up with an operating position outside the trailer. There, the public could observe ham radio in action and, with the guidance of licensed Club members, personally communicate with persons in distant and foreign places. Public information brochures, about ham radio in general, and about MDARC in particular, will be available to the public. "Ham Radio in Action" kit building stations will be available to visitors who would like to build an electronic kit.

Setting up at the Cowell Home Owners Association Safety Fair

Science clubs and electronics classes from schools will tour the trailer and "work some traffic" firsthand. A short lecture, with slides, will be available to the students, on a variety of HAM radio related topics, reinforcing the lessons learned in the classroom. Such topics as: a series and parallel light bulb demonstration of Ohm's Law, a demonstration of the correlation of electron flow in a wire and water flow in a hose, and an antenna theory demonstration will be available for the students.

There are rack mounting spaces in the back of the trailer for future expansion. This might include Club owned transceivers, amplifiers, test equipment, etc., as well as Ham MESH networking equipment and antennas. 

The MDARC Communication Trailer & Van at the Cowell HOA Safety Fair 

The Trailer Committee is charged with upgrading and maintaining the trailer. The current configuration of the MDARC Trailer should serve the Club for many years to come. Any hams that would like to participate in the use and/or upgrading of the trailer can contact Trailer Committee Chair Mike Warren, W6MEW, <>. Club members in good standing wishing to use the MDARC Communications Trailer must download the below two PDF files, read them thoroughly, fill out the Waiver & Release form, and return it to the Trailer Committee Chair or any Board Member.

The operational and educational opportunities for this trailer are endless and are open to anyone who wishes to participate in the use of this tool of the Mt. Diablo Amateur Radio Club.

lsl, mew, 07-02-19

MDARC Communications Trailer – Ready to Deploy