POTA

My DIY Drive-On Antenna Mast For POTA Activations

I have been doing POTA activations for a few years now, and I have been using an antenna mast that attaches on to my Reese hitch. It which works well. It doesn’t go straight out like most mast mounts do for Reese hitches but rather off to the side of my Jeep. One of my goals for a POTA activation is to have everything in my Jeep without loading anything. However, I have been known to forget my antenna mast mount for the Reese hitch.

Also as one of my POTA goals, I want to have everything I need for an activation in my Jeep ready to go. This way I don’t have to load anything, or forget anything. Since it is already in the Jeep.

My Mast Mount Off Of A Reese Hitch

I have had several people on ask about my mast mount using a Reese Hitch. So I have added a photo below. However this is for reference. This post isn’t about this mast mount. This is about a drive-on antenna mast mount that I can always carry with me in the Jeep.

DIY drive on antenna mast for POTA with a Reese hitch — My Old antenna mast mount using a Reese Hitch

This antenna mast mount uses two Reese hitch extensions that are welded on to a piece of 2″ square tube. It comes apart in two pieces. The vertical pipe on the left is welded on to a 2″ piece of square tube that fits into the Reese hitch extension. It works very well. The best part is that I can drive to a park and open the hatchback as if the antenna mount wasn’t there.

But like I said earlier, I have been known to forget to attach this antenna mount. Thankfully I also carry an End Fed Half Wave antenna as a spare antenna. The EFHW antenna seems to be a little better performer than the vertical wires I use. But it takes a lot longer to set up my EFHW than it does the Spiderbeam mast.

My vertical wire antennaa works quite well. And I will continue to use them as my main POTA antennas. For me the time it takes to set up an EFHW vs the Spiderbeam mast, the trade-off between a longer more difficult setup vs speed and ease isn’t worth it. I know a lot of you will disagree and that is fine. that’s just how I have chosen to run my activations.

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Can You POTA on 160 Meters? Lets Find Out!

Several months ago, someone on the Parks On The Air POTA Facebook page posed the question “Has anyone made a POTA activation on 160 Meters?” To be honest, I really haven’t given 160 Meters much thought, let alone for a POTA activation. So this got the wheels of thought churning in my head.

160 Meters is a unique band that covers the frequencies of 1800 – 2000 kHz. Its often referred to as the Top Band, not sure why, but it is. The biggest problem for me is the size of the antennas required. A classic Dipole antenna for 160 meters is approximately 246 feet. A full sized vertical is approximately 123 Feet. For most hams this is hardly practical – let alone for a POTA Activation.

Since my main POTA setup is with a 40 ft. Spiderbeam mast and a 35 foot wire hung from the top, I figured that would be my starting point. So obviously I would have to come up with some sort of shortened vertical antenna for 160 Meters. This made sense to me as I have had success building other shortened vertical antennas for my POTA activations.

My POTA station has an LDG Autotuner and all it needs is to have some sort of ground to work against, and a wire at least 1/4 wavelength long. What I do for POTA on 80 meters is have a coil that adds enough inductance to my 35 foot wire so that the autotuner “thinks” its tuning into a long enough wire. This works well for me, so I thought I would do the same for 160 Meters.

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A POTA activation of North Bass Island By KE8ONI and WB8ERJ

Sometime in March of 2022, my friend, Kevin, KE8ONI, posted on the POTA Facebook page asking if anyone was interested in putting together a POTA trip to North Bass Island in Lake Erie. I quickly jumped in and said YES! Kevin and I first met on Facebook’s Parks On The Air group. About a year prior to our North Bass Island adventure, we met up at Malabar Farm State Park, which is about 7 miles from my house. We hit it off right away – we both are just a couple of big kids that like to have fun.

About North Bass Island

North Bass Island is located in Lake Erie about 2 miles from the Canadian border, and about 18 miles from the Ohio mainland. It is of particular interest to us POTA activators because its a bit difficult to get to. Unlike the more popular islands in Lake Erie, is that the only way to get there is either by a chartered air service, private plane, or private boat. Because there is no regular air or ferry service, activating North Bass Island is more difficult than most other parks. Fortunately, Kevin’s brother-in-law and sister own a boat.

North Bass Island is mostly undeveloped and historically been used as a vineyard. There are roughly two dozen residents on the island. Most of the islands 688 acres is part of the North Bass Island State Park.

The Plan…

Since Kevin’s family was vacationing for a week in August, I reserved a campsite at East Harbor State Park for three nights. One of the reasons was because the weather on Lake Erie is unpredictable. We figured if we gave ourselves a three day window, we should be able to get our POTA activations in. This also allowed me to activate East Harbor State Park during those three days as well – not to mention some quality beach time with my daughter and her kids.

Additionally Kevin reached out to N8NI, who was going to be on Pelee Island operating POTA, which is only 7 miles from North Bass Island. We were able to work Nathan on 2 meters so we got the Park to Park!

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My Ham Radio Go-Box Build For Portable POTA Operations

Since getting into the Parks On The Air program a few years ago, it prompted me to build my own version of what is known in the world of Amateur Radio, a Go-Box. That is a radio station that you are able to quickly grab and go at a moment’s notice. Since Amateur Radio’s justification for our frequencies is emergency communications, or EMCOMM, it makes sense that all hams have some sort of Go-box.

There are all kinds of go-boxes out there on the internet. They all have their advantages based on the operator’s needs and requirements. Being one who likes to learn from others, I spent a lot of time searching and looking at other people’s go-boxes. I then chose various features I like and incorporated them into my own go-box.

Here is what I came up with

Go Box Requirements

Plug and Play – That is plug in power, antenna and go.
Operate on HF, VHF and UHF frequencies
Compact and reasonably light
100 watts on HF frequencies
Operate on SSB, CW and Digital modes
Computer built-in
Antenna tuner

Go Box Equipment

Yaesu FT-857D
LDG YT-100 Autotuner
Raspberry Pi Computer
Signalink Sound interface
K1EL WinKeyer
Powered USB hub
Powerwerx USBbuddy 12V to 5V converter
USB GPS Dongle for grid square / time sync

Here is a photo of my completed Go-Box:

As you can see, its not actually a Go-Box, but rather what I call a Go-Frame.

The photo above shows the Yaesu FT-857D and below it the LDG YT-100 autotuner. On the right side you can see the two antenna connections that come from the rear of the FT-857D.

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How To DIY A Shortened 20 thru 40 Meter Vertical For POTA

There is something exciting doing a POTA activation where you hike in with all your gear in a pack and activating a park running QRP power. Since my original post about my first QCX-mini QRP transceiver, I now have additional QCX-mini’s that allow me to work my POTA QRP activations on 40, 30, and 20 meters. This meant I needed to build a portable shortened vertical for these bands. This particular vertical antenna build is based on my original Shortened 40 Meter Vertical but with the addition of being able to short the loading coil at the proper tap point for resonance on the 30 and 20 meter bands.

One problem I had with the original 40 meter vertical antenna, was that I used two 1/4 wave radials, which conventional wisdom says you should use with vertical antennas. On 40 meters, they are approximately 33 feet long. Which makes it more difficult to deploy the radials when in a heavily wooded POTA activation.

1/8 Wave Radials?

In doing some internet searches I discovered that it is possible to use radials that are 1/8 wavelength long — Yeah it sounds crazy to me too, but if its true, then it would greatly help the radial deployment issue on 40 meters. Granted at reduced efficiency, but I figured it was worth a shot. More on this later.

Since I already had a 20 foot collapsible fishing pole for my 40 meter shortened vertical, that is what I used for this multiband antenna. Since this was going to be for 3 bands, I wanted the loading coil low enough so that I could easily make a band change without lowering the vertical. Again, I went over to the coil shortened vertical antenna calculator page which gave me my starting points for the loading coil. Tuning this antenna for all 3 bands seemed trickier than normal. My guess is that I am using only two 1/8 wave radials.

The diagram below are my final dimensions. Your mileage may vary, but this is what I ended up with.

shortened 20 thru 40 meter vertical for pota sota activations WB8ERJ

For the loading coil form I decided to use an In Sink Tailpiece. My reasoning is this, typically people use standard PVC pipe for the coil form, which is fine, but the wall thickness of the pipe seems unnecessarily thick for my application. My main concern here was to put less stress on the wire that is the vertical part of the antenna. A toilet overflow tube is much thinner and lighter and works just fine. The outside diameter of my overflow tube is 1.5 inches. I am assuming that is a typical outside diameter. I cut the Sink Tailpiece 3 1/2 inches long, but 2 1/2″ would have worked just fine.

I used the coil shortened vertical antenna calculator based on where the coil is to be located in the above diagram and came up with a total number of turns of 33 with a tap at 13 turns from the top of the coil. If you have a different gage wire, put that in the coil shortened vertical antenna calculator instead.

Initially I built the loading coil with the calculated number of turns. As it turned out, I needed more inductance. In the photo on the next page you can see at the top of the last turn I added more wire. Lesson learned, wind more wire on to the coil than calculated.

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Build A Shortened 40 Meter Vertical For POTA / SOTA Activations

Recently I went on vacation to Virginia and wanted to do some POTA activations using my new QCX-mini transceiver. On this trip I wanted to hike up to the summits of various mountains that are in various national parks. Since my QCX-mini is the 40 meter version, I obviously needed an antenna for it. My personal preference for portable antennas is to use vertical antennas as opposed to a dipole or other horizontally based antenna. Since my QCX-mini is 40 meters, a full sized vertical, being approximately 33 feet high, is a bit impractical.

UPDATE: I have built a new version of this antenna that covers 40 through 20 meters. If you are interested in building a 3 band version of this shortened vertical, click here.

I have seen others using collapsible fishing poles for antenna masts, so I figured I would give it a try. I found on Amazon.com a 20 ft. Crappie Fishing pole that collapses down to just 4 feet. I also found a web site that calculates what is needed for a coil shortened vertical antenna – perfect!

From what I have read, a base loaded vertical is less efficient than one that has the loading coil that is more near the top. The downside of placing the loading coil higher is that it needs to be larger, which will add to the weight, as well as additional stress on the pole in windy conditions. What I decided on was placing the loading coil slightly higher than the center of the vertical antenna.

Given my design constraints and using the coil shortened vertical antenna calculator, I settled on my shortened vertical antenna design. The diagram below is what I came up with:

build shortened 40 meter vertical antenna for pota sota acvitations

I used the coil shortened vertical antenna calculator based on where the coil is to be located in the above diagram and came up with 23 1/2 turns of # 24 enamel wire. I used 24 gage wire because I had it on hand. If you have a different gage wire, put that in the coil shortened vertical antenna calculator instead.

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