Pota

I was traveling to DC the weekend of ARRL Field Day, so I found some time e-bike from the hotel to activate US-0655, the National Mall from a park bench at the mall. I clamped the GRA-1900T right to the bench. Field Day was happening, so traditional bands were very busy. I jumped to 17m for a quieter, POTA-only experience. The LiFePO4 battery hadn’t been charged in a while, so it went dead by the end of my activation. It was a bit of a race against the dwindling battery. With the battery completely exhausted, and running on the internal battery of the x6100, I got to 12 contacts.

I had played with the radio the night before. I tried my gra-1900T and the 12.5m EFRW in the hotel room. We were on the 9th floor of 10 floors in Downtown DC. I barely got out for a moment on 40m with the wire, then nothing. The whip did absolutely nothing.

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.

US-1356 Pinchot

I setup at a pavillion far away from everyone else, so as not to burden anyone wondering what I was doing. Putting up the 20m-long EFHW, I got the socket and throw line stuck in a tree. I had to cut it loose.

I tried 10m for 2 FT8 contacts, but that’s all the further I could stretch that band. The rest of my contacts came on FT8 40m, and one P2P SSB contact on 40m before I packed up.

US-1418 Sam Lewis

At the second park, I operated mostly 20m with the GRA-1900 coil and whip. I was struggling to get that to the right settings, so I finally just extended it and hit the tuner on the radio.

I accidentally crossed the 0000UTC mark into the next day, which means it’s a new activation. I scrambled to try to complete the new day, but fell short.

After a bike ride in Harrisburg, I visited US-4356, Boyd Big Tree Preserve. I used the 20m EFHW sloped up into a tree near the main pavilion. I spoke to a park in Western PA, and a museum ship on Great Lakes in Toledo, OH. 15m FT4 was busy with lots of contesting, so I also ran some FT8 on 20m.

The go-box is over-stuffed again with extra rope. I need to slim it down again.

SPARC Elmer Night

I spent the Elmer Night tuning EFHW again with the NanoVNA. I proved that I saw the same graph when the antenna was stretched shallow vs a higher inverted-V.

I tried folding back the EFHW wire. It changed the tuning slower than cutting the wire. DX Engineering has a video about this. I didn’t get it finished at the meeting, since because it got dark.

Memorial Day Weekend POTA US-4361, Kings Gap Environmental Center

Matthew and I setup at Kings Gap Environmetal Center (US-4361) near the campground. I spent the most the time still slowly tuning my EFHW, and then dodging the rain. I barely made any contacts by the time I got the antenna in the air, and then the thunderstorms returned. We bailed, and I put the antenna up back at the campground strung over the site from tree to my fishing pole to telephone pole for the rest of the weekend. The twisted cords I’ve been using started unwinding, so it’s soon time to replace it with braided mason line.

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.

I ran out to Susquehanna Riverlands State Park (US-9719) to test the EFHW again. This time I tied it to a bush and a picnic table and raised the center with the fishing pole mast.

I took the time to sweep all the bands with the X6100’s built-in analyzer app. 40m looked like it could stand to have the wire slightly shorter, but when I transmitted, the SWR looked fine. I saw about 1.5:1 SWR on 40, 20, and 15. 10 was a little off, so I guess I’ll add the 100pf capacitor that most people use.

The tuner made 12m and 17m work, so I made FT8 contacts on 40m, 20m, 15m, and 17m.

I was also trying out some of the combo winder/unun I 3d printed and made some notes. I’ll post my remix soon of another person’s OpenSCAD code. I like the all-in-one designs that wrap up into one package, but I wonder how much that will hinder my random experimentation with antennas.

While transmitting, I noticed the Evolve 3 laptop’s mouse would stop responding. I had seen this on other laptops using the 1/4 wave HF vertical. I added the common mode choke to the feed line near the radio, and that cleared up. There was already a choke near the antenna, but I guess it wasn’t enough. I love when I can see a clear cause and effect or problem and solution.

Ben and I took the radio gear for a walk to Hawk Point overlooking the river in Susquehannock State Park (US-1425) for a POTA activation. We threw the 20m EFHW into the trees in an inverted-V. I checked the SWR on 15M, and it came in about 1.5:1 or so.

I could hear really well with it, and I contacted Argentina, Texas, California, and Italy among other closer places on 15M FT8. I spun the dial down to 20M SSB to hear a park in Illinois, but it was busy and the sun was setting quick, so I didn’t wait to try to make contact.

I’ll have to try the other bands next, but my randomly starting up on 15M worked great.

Using the little box as a winder for the wire didn’t work out so well. It became an immediate tangle as I tried to unwind it. I’ll switch to a 3d-printed winder instead.

My Week in Ham Radio

• Built and deployed a 1/4 wave ground plane with radials
  • wire soldered to an UHF chassis plug
  • fed from the bottom
  • hung in a tree by cord
• York Hamfest and 2 parks out that way
  • Codorus
  • Sam Lewis
  • EFRW
  • Mostly ft8
  • 40m hot at 5:30pm
  • 2 phone contacts in Canadian parks for park-to-park QSO
  • Took some time to experiment a little
  • Fishing pole mast with 3D-printed fork on the end to catch the wire
  • Stop pulling on coax…loosened ends
• SPDX RTTY contest (Poland)
  • 2 contacts
  • ended at noon UTC on sunday, so ran out of time
• AubsUK firmware for Quansheng
  • 10 scanlists
  • automatic scan on power-up, feature request
• Picked up a new podcast: Ham Radio Workbench
• Simplex Net: heard 16 of the 38 people

My Questions

• with nicer weather and time to experiment with antennas, how would you recommend iterating and experimenting? I have:
  • the QRP transceiver
  • digital modes & pskreporter
  • nanovna
  • some modeling software I could learn
  • the latest ARRL Antenna Book

Discussion

• Dipoles, sloped or flat?
  • Flat leaves nulls toward the ends
  • Sloped fills it in to be a bit more omnidirectional
  • An antenna close to the ground is going to be NVIS
  • Vertical is omnidirectional
• Ron’s seeing infinite SWR on the “screwdriver” antenna.
  • Others have had problems as well.
• Mike wonders about viability of using 6m FM in his area
• My Question: How should I evaluate and structure my experiments with antennas?
  • Conditions change constantly
  • Learn to read solar data
  • Take notes on conditions and try to test in similar conditions
  • Vic’s experiments:
    • endfeds
    • hamsticks
    • radials
    • aluminum screen or faraday cloth for ground plane
  • WSPRnet and pskreporter help gauge how you’re getting out
  • See what you can hear
  • Qualify callsign for different tests, so I can tell them apart in pskreporter: kc3wwc/a, kc3wwc/b, etc
• Ken wonders about TNC for packet radio on HF/VHF
  • Glenn, N3MEL would be the person to contact
• We heard lots of interference and doubling in the beginning of the net
  • This was likely another manifestation of intermod
  • Tropospheric ducting happens more in morning in the summer

York Hamfest

I ran to York for the Hamfest and I saw a handful of new friends from SPARC and 985. I only bought some BNC adapters, a speaker that’s OK but not great, and a wireless keyboard/touchpad for my Raspberry PI projects.

POTA

While I was out, I figured I may as well play a little radio and activate 2 parks.

Codorus, US-1342

I ran the 12.5m EFRW stretched from high in a tree to a picnic table. I started at the picnic table, but moved into the car when it started to rain. To reach the car, I stretched my coax a bit and camped that to the table, and I ended up with no signal. The feed cable (RG174 with SMA connectors) had pulled loose from the SMA connector, so I had to debug that and push them back together. I operated 17m mostly, FT8, and contacts came a bit slow.

Sam Lewis, US-1418

This time I stung up the 21.56m EFRW, 2-3m off ground on ends, stretched between trees, and a fishing pole mast supporting the middle peak. 17m was still a bit slow, but 40m was hopping for FT8. I had a steady stream of contacts.

Before packing up, I spun the dial and found a park-to-park SSB on 40m: 2 operators on one radio at the intersection of 4 parks in Canada, so that counted for 8 hunter points.