The Impatient Ham’s Perfect Vertical Antenna (And A Bit More On That Random Wire Tuner)

AA1F was celebrating a special day, so he needed a special present. While our love of radio is simultaneously growing, our ambitions in the hobby are different. AA1F embraces the “appliance operator” label, wanting easy to deploy gear that consistently works so he can reliably and rapidly get on the air and make contacts. Me, well, I am starting to (try to) build radios. And for anyone who reads this blog, my enchantment with antennas should be obvious.

AA1F has been searching for the perfect portable vertical. You know, the unicorn that doesn’t need radials? Or tapping of coils? Or special guying or rigging to keep it upright? Or any longer than a thirty second deployment? The one that the Easter Bunny, Santa Claus, and the Tooth Fairy all take with them when they go out for a Parks-On-The-Air activation?

Well, it turns out, it does exist…

That is the MFJ-336T Tri-Mag 3/8″-24 thread mount. And next to it is the MFJ-1979, a stainless steel,17′ telescopic whip antenna. And since I refuse to share my antenna analyzer, I also got him a RigExpert Stick-230 to put in his kit. (Shown below next to Nellie’s paw prints.)

We did some initial testing of the antenna in our house; it looked promising. It rained for a few days before AA1F had a chance to try it out. Eventually the initial attempt at a local park showed a rather unstable SWR, and what seemed like RF getting back into the transceiver based on the description of noise AA1F was hearing. Regardless, he did make a couple of contacts in the midwest.

To address this, I fashioned a 6-loop choke in the attached coaxial cable near the magmount. We waited for some nice weather to test it out together. And when there was no nice weather, we tested it out anyway…

We fully extended the antenna and screwed it into the magmount that was already positioned on the roof. A check of the SWR showed that the antenna was a bit electrically short, but still perfectly tunable with the LDG Z-100 Plus autotuner. The way to read the Stick-230 is that the center frequency of the graph and the range are displayed at the top (14.250MHz +/- 500KHz). Frequency is on the horizontal scale, whereas the SWR is on the vertical scale. At the bottom, the SWR of the center frequency of 14.250MHz is shown as 2.3 and the lowest SWR on the graph is shown as 1.87 (which would be at 14.750MHz after evaluating the chart).

Interestingly, I noticed that AA1F was a bit hesitant to let me touch his new antenna analyzer… I know the feeling!

The first test was an activation of Willowdale State Forest (K-4755) in Ipswich MA. Look closely and you can see Nellie in the passenger seat.

AA1F activated from the back of Limey. In about a half hour, he made 30 contacts. Success!

I too operated, but only made two contacts on 17 meters. Off the end of the table, my antenna wire of uncertain length heads off upward into the trees.

There is a bowline knot tied toward the end of the wire. This is used to secure the wire to the bench with orange paracord. If you look carefully at the free end of the wire, you can see a banana plug termination.

Here is a closer look at the bowline knot. The paracord is stretched back out simply to provide a visualization so that no one runs into the black wire at this public park.

The banana plug of the antenna wire is inserted in the center conductor of the SO239 connector on the back of the MFJ-16010 random wire tuner (described in this post and this post).

The rest of my set-up consists of a transceiver (Yaesu FT-891A) plugged into a battery (Bioenno 15ah LiFePo). The transceiver then is attached via coax jumpers to a 17M bandpass filter, a 1:1 balun, and the MFJ-16010 tuner.

The SWR curve without the bandpass filter in place and after tuning looks like this, with SWRs <1.5 across the 17M band.

And with the 17M bandpass filter in place (showing an SWR dip at only the 17M band). Without the bandpass filter, I could hear AA1F transmitting into my antenna.

Despite the promising antenna analysis, the random wire did not perform very well for me. By the time I made a second qso, it was raining, and I needed to pack up. We headed off to Bradley Palmer State Park (K-2422) in Topsfield MA so that AA1F could get a second unique POTA activation for the day.

Setting up the antenna was a breeze. Despite the fairly heavy rain, AA1F continued to operate. He made 19 more contacts on the 20M magmounted whip, for a total of 49 contacts in less than an hour on the air. In fact, he also DX’d with England, Spain (three times), and the Dominican Republic. He made it out as far west as Idaho and Arizona. He even had a few local Massachusetts contacts. The coax choke was decidedly helpful in stabilizing the SWR and keeping RF from reaching his transceiver, with a noticeable improvement in the noise level.

They say all antennas are compromises. Well, for this multiband magmount vertical 20M sans radials, the compromise is definitely in AA1F’s favor! And even though I only made a paltry 2 contacts, the fun of setting up and experimenting with different antenna systems is so so worth it!

‘Til the next one!
KM1NDY