AB4BJ Portable Antenna System

I had a blast in 2016 participating in National Parks on the Air (“NPOTA”).  It was one of the best ham radio experiences I have ever had in 26 years as a licensed amateur radio operator.  When I started out with NPOTA in January, I had very little experience as a portable operator and began to stumble through the process of setting up a portable station.  I purchased a Budipole system that worked very well, but soon realized that I preferred to operate NPOTA park units from my vehicle as a portable operator, i.e., stationary.  After seeing the setup used by Bob Voss, N4CD, for NPOTA and county hunting, I emailed him for some of the specifics.  Bob was very helpful and gave me great advice.  Armed with Bob’s advice and a general idea of how I wanted to set up the portable/mobile station, I got to work and created an antenna system that performed very well.   As the NPOTA year progressed and I activated 65 unique parks for a total activation count of 280, this antenna system never failed me, always got good signal reports and was very quick to set up and take down.  Many hams have asked about the specifics of this antenna, so I thought I would share the information in this post.

All of the parts for the antenna came from Tower Electronics (the mag mount) and DX Engineering (everything else) but other ham radio retailers will likely have these items.  You can download the PDF of the complete parts list and the way I assembled everything.  The PDF will provide you everything you need to know to build this antenna.  In the event you cannot download or read the PDF, here’s the parts list and assembly procedure I used to build the antenna:

Parts List:

From DX Engineering Web Site

2 X HSR-QD-2 –  Mast Coupler, Quick Disconnect, for Mobile Antennas, 3/8-24 in. Male Threads, 3/8-24 in. Female Threads

4 X   DXE-5MTCF-1 –  Mast Coupler, 3/8-24 in. Male Threads, Hex Center, 1.810 in. Overall Height

1 X   DXE-MT-72 –  Antenna Mast, Mobile, Heavy-Duty, 3/8-24 Internally Threaded Ends, 0.5 in. Diameter, 72 in. Length

1 X   HSR-VP-1 – Hustler Tri-Band Resonator Adapter for HF Mobile Antennas, fits Hustler 3/8 x 24 Stud Masts

1 X   HSR-RM-40S –  Resonator, Super, 1,000 watts PEP, 40 meters Band, Whip, 3/32 in. Allen Key

1 X   HSR-RM-20S –  Resonator, Super, 1,000 watts PEP, 20 meters Band, Whip, 3/32 in. Allen Key

1 X   HSR-RM-17 –  Resonator, Standard, 400 watts PEP, 17 meters Band, Whip, 3/32 in. Allen Key

Not from DX Engineering Web Site

Tri-Foot heavy duty Mag Mount with 3/8 thread (purchased from Tower Electronics at Dalton Hamfest)

Assembly:

  1. The mag mount came with coax assembly that had to be mounted into the center hole of the tri-foot mag mount base. Make sure the antenna mount is a 3/8-24 female thread.
  2. Connect the three Hustler resonators to the HSR-VP-1 tri-band resonator adapter with supplied hardware.
  3. Attach a HSR-QD-2 quick disconnect to each end of the DXE-MT-72 mast.  You may need the DXE-5MTCF-1 threads for these and other connections.  The goal is to be able to quickly connect and disconnect the top section of three resonators from the mast and the mast from the mag mount assembly.
  4. When completely assembled and ready to use, the top resonator assembly will be connected by HSR-QD-2 quick disconnect to the top of the mast and the bottom of the mast will be connected by HSR-QD-2 quick disconnect to the mag mount base.

I believe that the key to the very good performance is the 72 inch mast (as opposed to a shorter version).  After my initial assembly of the antenna, I spent quite a bit of time trimming the radials of each resonator to get the best SWR.  I used a Rig Expert AA-600 antenna analyzer to assist in this process.

The key to quick set up and removal are the two Hustler QD-2 quick disconnects I have on each end of the mast.  I have found that I can set up or remove the antenna from the top of the SUV in about 5 seconds (leaving the mag mount on the roof).

Here are some photos of the various parts of the antenna:

Here are some the photos of the antenna installed and being used for NPOTA:

Finally, here is a video of me taking the antenna down after my very last NPOTA activation on 12/31/2016:

Please let me know if you have any questions about this antenna.

73, AB4BJ

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2 Responses to AB4BJ Portable Antenna System

  1. jeff says:

    Nice antenna but you have to have a vehicle with actuall metal in it to get it to stick on top of the vehicle for it to work most cars are fiberglass i know mine is saturn 2006 vue

  2. Bill says:

    Fortunately, the roof of my vehicle is metal! A similar design, without the mag mount, could be employed with the trailer hitch, but the performance would not be as good. 73, AB4BJ

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