Review: MFJ-1906HD telescoping mast

Ordered an MFJ-1906 fiberglass mast from DX Engineering over the weekend and it arrived at the house yesterday.

I ordered the 33′ hose clamp version of the mast, but what ended up at the house was the 38′ quick clamp version (MFJ-1906HD). Even the label on box said it was the hose clamp version. Factory labeling error I guess. Can’t really fault DX Engineering for sending the wrong item.

MFJ-1906 box label
MFJ-1906 box label

Instead of the expected six 6′ sections of fiberglass tubing inside the box, there were seven 6′ fiberglass tubes along with 6 quick clamps. It’s a pretty compact package. One 6′ x 2.5″ OD tube with all the others nested inside.

The quick clamps need to be glued to each mast segment so that they don’t come off while you’re extending each segment. The only suitable glue I had was epoxy, so I just used that.

Final assembly is just a matter of adjusting the quick clamps so that the tubes slide into each other and holds securely when the clamp lever is in the down position. I marked the bottom end of each tube at 12 cm (the instructions suggest marking them at 1 ft (~30 cm) as an indicator to stop pulling each tube out.

Final length is just over 2.1 m (7′) and fully extended (leaving about 12 cm nested inside the previous segment) the mast is about 12.2 m (40′) long. Leaving about 30 cm nested in each segment would bring the total length down to just over 11 m (37′), which is still plenty long enough for my purposes. Probably a good idea to leave the thinnest tube nested a little further inside for extra strength, especially on a breezy day.

The mast seems pretty sturdy, although I can tell that getting it up is going to be at least a two person job. At somewhere around 10 kg (~20ish lbs), the mast doesn’t weight a whole lot, but the length can make it bulky and unwieldy. The quick clamps should easily hold each segment well enough for the mast to support a wire or other light weight antenna.

The quick clamps seem like they’ll need readjusting, especially if they’re being locked/unlocked frequently. Don’t drag it on the ground while you’re carrying it around, especially on hard surfaces or you’ll end up grinding away the mast.

Now to figure out how to secure the dipole to the top of the mast.

8/10 stars. (10/10 for value in my case).

Review: Emergency Power for Radio Communications

I added Emergency Power for Radio Communications (2ed) to the library a little while ago and with the move to the new house soon, thought it would be good to give it another read.

The book covers a wide range of options for lighting when power goes out, generating and storing power for your shack, instrumentation for monitoring and safety.

Generating power is covered by chapters on solar, gas generators, wind turbines and even a short blurb on hydroelectric generators. Chapters covering load sizing and battery systems are very informative. The battery chapter talks about several different types of batteries, with the bulk of the chapter covering the venerable lead acid battery. There are several examples of large battery banks and how to install and maintain them.

An appendix (one of three) collects a bunch of useful articles from past issues of QST, including projects, reviews and informational articles.

Most of the content is geared towards supplying supplying emergency and backup power for fixed installations, but the many of the ideas and concepts in the book can also be scaled down for mobile and portable stations as well or applied to powering anything electrical.

Overall, the book is pretty easy to read and contains a lot of good information that will come in handy. I learned quite a bit reading this book.

This would be a good addition to the bookshelf if you’re

  • looking for power ideas for portable/mobile ops
  • thinking about adding emergency/backup power to your shack
  • augmenting an existing emergency/backup power system
  • wanting to learn more about power systems in general

I’ll give this 5 stars out of 5.

Review: ARRL Satellite Handbook

The book is split into two parts. The first part covers some history of amateur radio satellites, software and terminology, and some of the gear you’ll need.

The second part consists of several QST articles describing simple antenna and rotor controller projects that can be used for satellite contacts.

Two appendices let the reader get down and dirty with the math and physics of satellite orbits and the various components and subsystems that go into satellites.

There’s a good discussion of Keplerian orbital elements (“Keps”), which are essential to figuring out where and when to look for a particular satellite. Fortunately you don’t need to use them yourself, software takes care of all of that. Unfortunately the discussion about Keps is made a little bit confusing by using three completely different sets of numbers in the tables showing different Keps formats and the text describing each of the elements.

One of the projects is titled “Work OSCAR 40 with cardboard box antennas!”, a great example of how you don’t need fancy expensive gear to hear satellites.

I think I’d call The ARRL Satellite Handbook more of a primer than a handbook, which implies something more comprehensive. Still, it does a pretty good job of covering what you need to know to start working the “birds”.

4 stars out of 5.

Review: Radio Science for the Radio Amateur

Radio Science for the Radio Amateur is one of the more recent ARRL publications that I added to the bookshelf.

At a couple hundred pages or so (it follows the ARRL’s annoying chapter-page numbering rather than using regular page numbers), the book is pretty light reading and should be pretty easy to get through in one or two reading sessions.

The concept behind the book has a lot of potential, but this attempt doesn’t go deep enough into anything to be all that useful. I’m left with the feeling of “Oh, that’s pretty neat” but then end up grasping at air because of the lack of substance.

One significant flaw in the book is the lack of references and other resources that readers can go to for more information. For example, the circuit simulation chapter mentions SPICE and tells you it can be used to simulate circuits, but that’s it. You’re left to go find additional information on your own. A list of resources (books, websites, etc) at the end of each chapter would be immensely useful for such an introductory level book.

2 stars out of 5.