Antenna

My 12.5m EFRW at home broke again, so I needed to restring it. The wire breaks at the tie point up in the tree. The kids and I failed to launch it again over the tree with slingshot out the window. I had also tried some small 3d-printed s-biner clips, but they’d release as soon as I launched with the slingshot I got the wire running flat through the other tree instead of up and over.

That didn’t last too long. The wire broke again at the tie point, so I launched it from the street again with the throw line and sockets. I kept it a little looser and switched to a bungee cord to keep it tensioned with some play.

There are easy instructions to build your own yagi on Instructables. I had just picked up some hose clamps and had the other necessary pieces: a broken tape measure and some 3/4-inch schedule 40 PVC and connectors; so I was ready to build.

The wiring on mine is held in place by the clamps and banana clip adapter. I always like those for prototyping. As directed, I tuned the antenna by moving radiators in and out and measuring with the NanoVNA.

The antenna is noticeably directional, so I can use it to find directions of signals. The S-meter and dB signal strength numbers on AUBS firmware make it easy to evaluate strength and direction.

I transmitted with it to the K3IR repeater as a test during a net.

Initial Tuning

The one-page document that comes with the GRA-1900T antenna detailing the jumper positions on the coil and the lengths at which to set the whip for each band didn’t seem to match up all that well, which led to some frustration out in the field.

I decided to use my NanoVNA to reconstruct my own instructions for using the antenna. I extended the whip fully and recorded the resonant frequency for each jumper position of the coil. Knowing those frequencies, I can set the jumper and shorten the whip until the SWR sweep on my x6100 is happy. The SWR graph on the x6100 can be misleading sometimes, because it often shows a birdie dip or 2 in the graph, but now I’ll always know that I’m to shorten the whip to get where I need to be.

I’ll eventually apply labels to the coil with these frequencies.

US-1425 Susquehannock State Park

I took the GRA-1900T out to Susquehannock State Park for a field test. My plan to tune the antenna worked well. I set the jumper for the frequency below my intended operating frequency and shortened up the whip until the x6100 showed a good SWR curve. Easy!

Oops, Broken Fishing Pole Mast

Since I hadn’t used the fishing pole at the park, I forget I had it and left it behind when I packed up. 2 days later, I returned to retrieve it. Some kids had found it, had trouble collapsing it, dug in the dirt with it, and broke a section.

I was able to put it back together with the remaining sections, and I 3d-printed a new fork/loop to make it useful for supporting wire.

My antenna wires at the house were getting moved around a bit with some projects. I found my SWR was a bit high on a certain HF band, and I found moving or coiling the counterpoise (~5.2M) to shorten it greatly reduced SWR. I have to remember to watch performance and adjust the counterpoise as part of my setup and operating.

I removed the magnet from the inexpensive mag-mount antenna that I had stuck to a baking sheet in the back of the BMW i3 (which is all plastic). The bike rack is always on the car, so I cobbled together some scrap metal parts and clamped the antenna onto the rack. It’s got a screw knob, so I can loosen and reorient it when I flip the bike rack.

It works great now with the antenna outside the car and attached to the metal of the rack.

My Week in radio

The Vertical EFHW

I Tested my 20m EFHW wire and unun on 2 different POTA outings In an inverted v with a counterpoise, it worked pretty well, but could be shortened. As a vertical, the SWR was higher, and the counterpoise made it worse. I compared the vertical EFHW to the trusty old EFRW in a mostly vertical configuration. That one had exhibited a terrible SWR as well with or without counterpoise. Maybe I needed more radials instead of a counterpoise? I have 2 ARRL antenna books, basic and the big one, so I could read, I suppose. During these experiments, my computer experienced some common-mode interference too.

Custom Antenna Winder

I 3D-printed a nice customized winder with the transformer attached. I modified the code to be parameterized to any size I want.

More VHF

I’ve been discovering I can hear some further repeaters using the spectrum analyzer feature on my Quansheng, so I’ve been adding more repeaters to the scan.

Thoughts on My Vertical Antenna Problem

• You can tune and end-fed at one angle, and it can have a different swr at another angle.
• They’re sensitive to objects in their near field. Is the unun near ground or branches? The same goes for the other end of the antenna. Try changing the orientation.
• The ends are high-voltage, so they’re sensitive to capacitance. The middle is high-current, low-voltage.
• Vertical antenna will have very different conditions at each end. inverted-V or horizontal will have more similar conditions at each end.
• RF comes from the current in the middle.
  • Vertical is an inexact science.
  • The tree effects it.
  • 50ft of coax helps provide RF ground, and less can be a problem.
• Watch height of unun.
• The Smith chart on the NanoVNA can help evaluate what’s happening.
  • Crossover point on the chart can show the tuning and the swr
  • Is it environmental or the wire?
• Counterpoise placement can be sensitive.
• Add radials for vertical.

Interesting Bits from Other People

• Tim, W3QP, did the W2 SOTA campout: 6 summits and 32 contacts, mostly VHF.
• Chuck, NA3CW, talked about accomplishing an 75M net using online WebSDRs to hear, because propagation was so bad.
• Rob, K3VIL, is having fun with his QRP IC-705.

I compared the 20m EFHW with the 12.5m EFRW at Sam Lewis (US-1418). I threw really high and made both antennas nearly vertical into high trees, not inverted-v.

EFHW could hear pretty well, and the SWR sweep showed again that I could shorten it, so I did lower it and take off a few cm.

The EFHW didn’t seem to like its counterpoise. With the counterpoise, it was giving me an SWR of 2-2.5:1 on 40m when I transmitted. If I removed the counterpoise or kept it coiled up, the SWR was lower. I still made most my contacts on 40m.

I think the radio may have again been interfering with the mouse when transmitting. I already had chokes on both ends of the feed line, but adding the counterpoise helped that common mode interference. It was a rough day.

The EFRW would not tune well at all on 40m with or without its single counterpoise. That surprised me greatly, because I had tested that same unun with my existing EFRW antenna out the front window at home.

I wonder if it had something to do with each antenna being mostly vertical. I wonder if they needed more radials instead of a single counterpoise. K4OGO (Walt of Coastal Waves and Wires) always adds so many radials to his verticals.

This had me questioning everything. I thought I was doing something really good by getting the wires high and vertical. When I brought the radio home and connected to the same old EFRW, it was again performing normally.

I also learned that the POTA website cuts off your activation and starts a new one at 00:00UTC, 8pm, so I ended up with 2 QSOs counting toward a second (incomplete) activation at the park.

My Week in Radio

• I purchased some power cables that split out the 12V line out of USB-C, so I can power my radio from a USB-C power brick/jump-starter battery.
• Marie and I relaunched my EFRW even higher into the the tree in the front yard. I used the slingshot out the second-story window, while Marie watched that the street and sidewalk were clear.
• I did the RTTY test and FT4 sprint last Thursday.
• I saw some better propagation on FT8 before the weekend’s solar storm: Ukraine, Northern Ireland, and Greenland at the arctic circle.
• While the bands were dead over the weekend, I built a couple new, lighter antennas for POTA. I cut and tuned some 20m-long EFHW wires and tuned them with NanoVNA. I used recycled plastic gum boxes as enclosures and winders for the un-uns and wires. I also 3d-printed a winder that holds the transformer and heavier speaker wire. I’ll test the antennas when bands are obviously better. I’ve not really used an EFHW much, so I’m curious to see how it performs compared to EFRW.
• I saw some recovery today in the band today: Panama, Canary Islands, and the Cayman Islands.
• Ron, WA3VEE, sent photos from the Antique Radio Meet in Kutztown.

My Question for the Night

What are the effects of solar cycle and solar activity on propagation? We’re in a high point of the solar cycle, so 10m is good, but too much and it blacks out propagation?

Discussion

• Vic, KC3TYX, made a VARA-C contact.
• Jim, KC3RFG, found an OCF dipole to be quieter than end-fed.
• Jim, AF3Z, has trouble with his Ten-Tec radio sometimes not transmitting.
• Jeff, W3JAM, wondered if anyone was making 6m contacts over solar storm.
• Mike, W3MFB, noted that 17m sometimes is a pipeline right into Florida in afternoon/evening.
• Tim, W3QP, is headed on SOTA campout.
• Jack, K3YVQ, Is it OK to use GMRS on a radio that does ham freqs and more?
  • Mike, W3MFB: technically, the radio should be locked to gmrs frequencies.
  • on the air, no one would know, though.
  • Ron, WA3VEE: FCC approves radios for particular services.
  • GMRS radios are “type-acceptance”, and the right power limits.
  • Some other radios might be hard to limit to the right power.
• John, KC3WWC: What’s the solar storm do to propagation? Some activity is OK, but too much is bad?
  • Chuck, NA3CW:
    • RF is produced by accelerating (“wiggling”) electrons.
    • Ionosphere doesn’t “bounce” signals, but instead “receives” and “retransmits”.
    • We have loose electrons in the upper atmosphere, good for retransmit.
    • Solar storm ionizes the atmosphere at different levels with varying intensity.
    • Our RF hits ions in lower part of the atmosphere and gets slowed, absorbed (D layer).
    • LF is affected the most, since it moves the electrons further.
    • Solar minimum offers less ionization at any level.
    • D layer, E Layer, F1 layer, F2 layer.
    • Better shortwave propagation at night.
    • Lots more is understood now about the ionosphere.
    • Frequencies are coordinated in SW to adapt to seasonal changes.
    • Electrons free in thicker air recombine more easily, so don’t pass RF.
    • Winter: great distances, because air is thinner.
  • Tim, W3QP: noise also comes up during storm and masks signal.
  • This video from Coastal Waves and Wires explains the effect a bit.

The bands were dead with the terrible geomagnetic storm this weekend, so HF is very limited. I was only able to contact Lititz from Mountville.

With the downtime, I built some new EFHW antennas. I tied some wires to trees, stretched them out, and tuned each of the 2 20m EFHW antennas with the NanoVNA: one speaker wire, and the other lightweight silicone wire. I built new ununs and mounted them in plastic gum cases and a 3D-printed winder.

I also cut a lightweight EFRW, 12.5m, from the silicone wire and gave it a gum case as a winder.

I’ll test the new antennas soon when the bands are better.

I cleaned up the backyard a bit, and ran a new 12.5m (41ft) random wire up the hill behind the house.

My first tests the next day on 30m at 1W got me some contacts. By 4:40pm EDT, the bands were all in “poor” condition, so it got tough to test.

The next morning, I watched the 40m band close. It was ablaze at 8am, but getting pretty quiet by 10:30am EDT.

I compared the old antenna out the front with the new antenna out the back using FT8 and PSKReporter.

The back antenna saw fewer decodes on 15m on average. It mostly lacked any stations from Europe. Looking at the antenna’s physical attributes, it starts on first floor (lower than the old antenna) in backyard, but it slopes up more vertically. The middle of the antenna, on average, is blocked by the hill to the East.

The old antenna out the front saw more decodes overall, including Europe. It starts at second floor window and only slightly angles up. The whole antenna is higher and clears the hill, even though Europe may still be mostly all the end of the antenna. It performs better.

I had fun physically launching the new antenna, but I’ll need to do some more work to get more of it higher in the air to be useful.