RF Chokes and my NanoVNA

Spent some time last week working with my NanoVNA. I've had the VNA for a couple of years now  but used it mostly for checking SWR on my antennas. It's the 4-inch screen model, which is easier on the eyes but still small enough to throw in my go-bag. 

I've had a few issues with RF in the shack causing some interference. I use a multi-band vertical and an 80-meter dipole as my primary antennas. The vertical is prone to producing some RF on the coax so I built a couple of chokes to help eliminate the problem. After watching some YouTube videos on using the NanoVNA properly (I really like Barry's videos - https://www.youtube.com/watch?v=qqhYILhsC38) , I was thrilled to be able to measure the signal loss on each choke.

I started by building a testing jig which allowed me to use the "Through" function of the VNA with a choke inline. I cut a set of alligator clips to use with it and wrapped it all in heavy-duty shrink wrap to protect it. My "Ugly Balun" choke was fair. Probably enough to be ok at the lowest frequencies, but not efficient higher up the dial. I then built a choke with RG-316 coax and a 140-43 toroid. This one was much better across the band. I took the opportunity to also install my grounding box with lightening arrestors at the same time. 

 

 

Testing out the new QDX GoBox

I love QRP Lab's stuff and and I've really enjoyed the QDX! I recently took my QDX and built it into a weather-resistant case I picked up at Harbor Freight. I used marine-grade HDPE plastic to create a panel that fit in the lid of the box. The box happened to have small cylinders in each of the corners, so I used by tap kit and cut some threads in them for screws. Then I mounted the QDX, a RaspberryPi-4 computer and 7-inch HMDI screen that runs on 12 volts. I routed all the wires behind the panel and down to the box. 

For the time being, I'm using pull-apart foam to hold things in place but I'm considering a more permanent panel in the bottom as well. Using a 6-amp/hour LiFePO4 battery, I powered everything in the box. The Pi and the screen run on a USB plug connected to the battery and the QDX runs at 12v via a buck converter to keep the voltage from spiking and risk blowing the power transistors. 

Stations which heard by signal on 30m

I took the setup to my local park and hung my End-Fed-Half-Wave (EFHW) multi-band antenna in a tree and configured it for 40 meters. I fired up WSJT-X and almost instantly I was decoding FT8 stations. I made a few contacts before switching to 10 Mhz. Fortunately, 30 meters was HOT with station consistently loud across the band. I then switched to JS8Call and, again, there were lots of stations. I sent a heartbeat and got a dozen responses. Sadly, I called CQ for about 15 minutes with no takers. 

Still, I seemed to be getting out nicely, especially according to PSKReporter. With the sun starting to set, I packed things up nd headed to the house. All in all, I am very pleased with the rig and the whole setup. Now I'm looking forward additional trips out into the wild!

Stations which heard by signal on 40m

Improving the QCX-mini power

I recently built my second QCX-Mini, this one for 20 meters. It's such a fun a build and even more of a joy to operate. I took it out to my local park for a test run using my homebrew, end-feed, half-wave, multi-band antenna. When the radio came on, the band filled with signals from a CW contest. I tried to respond to a few station, but apparently no one could hear me. I texted a friend who lives nearby and he was able flip on his HF radio and verify that I was indeed getting out. 

Back at the house, I pulled up Hans' video on maximizing output power on the QCX and sat at my bench to work on mine. I hooked it up to an RF power meter and found my rig was putting out a whopping 1/2 watt. No wonder no one could hear me. 

I adjusted the L3 inductor by spreading out the windings and managed to get right at 4 watts. But regardless of how much more I worked with it and the other two inductors, 4 watts was the most I could get. So, following Hans' advice, I desoldered the inductor and remove two windings. Once I soldered it back on the board I was able to get just over 6 watts. Perfect! I closed up the radio and packed it in the bag. 

This weekend, I took it back out to the park. Again--being a Saturday--the band was jammed packed with contest signals. However, this time, after waiting for a pause in an exchange, I called a station sending CQ. Instantly he returned my call! I gave him the exchange and he sent, "TU." It worked! I had about an hour of daylight left, but I wound up with 14 QSOs, all of them solid exchanges. 

TinyPaddles are a HUGE deal!

As the Christmas holidays approached, I decided to give myself a small and inexpensive gift...a new set of paddles. Mind you, these aren't just any set up paddles. These are a SUPER tiny micro-paddles! Called the "TinyPaddle," they were designed built by N6ARA. You can buy a kit version, but I opted for the assembled set. I first saw these on Tom Witherspoon's (K4SWL) site, qrper.com. I finally ordered a set just before Christmas and they arrived before New Years.

These are indeed very small! The paddles are soldered onto a circuit board and the board is insterted into a 3D-printed holder. The assembled version comes with a case which is basically a 3D-printed sleeve to protect the paddles when stowed. I also ordered the cable. The both came with an adjustment tool to carefully bend the paddles in or out as a way of adjusting the feel of the paddles. He also sells a version with the male plug instead of the female jack, in case that fits your setup better.

After playing with them for a little bit, I have to say I really like them! No, they don't feel like a $200 set of paddles. But, then they only cost $24! They are perfect for backpacking, POTA (my use), SOTA (not in Texas!) or any other ultralight station bag. I'm a sucker for cool, lightweight, micro gadgets and these certainly fit the bill!