Mini Repeater Trailer

If you are an avid event organizer without a club infrastructure or you organize events in multiple communities, like I do, how many times haven’t you wished for a mobile radio site for repeaters or allstarlink(s) where you could simply place it in the best location for the event?

The trend for my events is that our ham event-community is dwindling is size/participation and that I commonly add commercial radios for segments of the event to have enough support.

The Objective:

Have a light trailer which can be dropped in the “ideal” location for an event repeater or radio access point (AllStarLink / High Power Hotspot) with reasonable antenna height. Kind of the missing “swiss army knife” of portable event communication. 

Background:

When I organize Comm Logistics for an event I am never the “Net Control” in a fixed location. I am typically one of the organizers and I am very mobile within the event. Thus, I cannot simply park my vehicle in the best place and work from this location. In fact, most of my events do not have a fixed “net control” in Ham sense, but a very tactical net with direct access to decision makers. I don’t mind a semi formal “net” with a net controller, but I find it frustratingly inefficient when the people in command is separate from the people with radios. Thus, I mix ham and commercial radios as needed. When I use ham radio, the service becomes a part of the event rather than segregated offset in parallel. If my Net Controller is not a Decision Maker then we use semi-formal nets and the Net Controller only maintain the welfare of the volunteers while decision makers answer questions. This net controller may have both ham and biz-band to coordinate this. This cuts down the time from a query to a decision.

The guys at Ham Radio Tower Trailers have the right idea. Their project is great for a group – love to be a part! But maybe too ambitious for one guy to do alone between the procurement and refurbishment. Thus, here comes Knut’s scaled down mini version:

The trailer is a repurposed home made motorcycle camper luggage carrier. It is very light and based on a upgraded Harbor Freight undercarriage. Perfect to be pulled behind my GLK350 SUV. The box is made of plywood and covered by a outer skin of weather resistant material. My purpose is to drop the trailer with its radios at a high spot and leave it for the duration of the event.

Planned Comm Equipment:

Every event is different, but here is a list of available options ready to be loaded:

• LTE Internet
• APRS I-Gate to internet (5w Digipeater available)
• APRS Digipeater 50W
• DMR UHF Repeater (Ham and Biz-Band) in 19″ go-boxes
• Analog 70cm Repeater (Ham and Biz-Band) in 19″ go-box
• Cross-band VHF-UHF DMR and Analog (Ham or Biz-Band)
• AllStarLink Node in 19″ go-box
• 20′ Antenna Mast
• Misc Antennas for above projects

Let’s face it – one does not need all of this for every event. The trailer will function as a shelter for power and the needed equipment and as the antenna base.

Yes, it is a project, but a reasonable achievable as such. More pictures to come as “little grey” converts to “little green”.

The Plan:

• The box become the repeater/radio shelter.
• On this side, mount 2 horizontal u-struts along the top rim and bottom. This becomes the clamp rail for aluminum antenna mast sections. Goal is sturdy enough for 15-20′.
• The front deck is suitable for a honda-type inverter generator.
• The back wall needs to be cut into sections to be able to create an access door. I’m thinking a simple slide-out design rather than hinged??
• The top panel is hinged in the front and opens from the back. Therefore, need the rear access to place equipment. I do not envision the electronics to be hard mounted due to the rough ride??
• Add a aluminum diamond plate on the top lid as a ground plane for surface (not mast) mounted antennas.
• Trailer was used as a home-made motorcycle camper trailer. Thus the tentpole tubes. No plan for those yet. May or may not remain. Could become antenna storage??
• Power will be from a deep cycle battery (short term events) supported by a Honda 2000 inverter/generator. Other than loading and offloading, weight is not an issue.
• Outriggers on the rear is high probability for stability.