POTA

How to DIY an NVIS Antenna AKA Cloud Burner Antenna Using a Mag Mount

Part of being a ham radio operator is to provide communications in times of emergencies. With the upcoming Ohio NVIS Antenna Day, I decided to look into NVIS antennas. NVIS antennas, also known as Near Incident Vertical Skywave antennas have a high angle of radiation. Something on the order of 60 degrees, to straight up to 90 degrees. Unlike UHF and VHF signals, which typically have a 50 mile range with a yagi antenna up high, a NVIS antenna is designed for communication in the 75 – 500 mile range. Sometimes an NVIS antenna is referred to as a “cloud burner” since is directs most of its radiation more upward than a typical antenna.

The idea with a NVIS antenna is to radiate as much power as possible at a high angle and have it be reflected off the ionosphere. From a practical standpoint, NVIS communications occurs at 10 mHz and below. Another part of the NVIS antenna is the fact that it is quite low to the ground. This helps radiate the signal at a high angle, as well as make it easy to deploy. There ar many opinions as to the best height of an NVIS antenna, but everyone seems to agree on aprox. 1/8 wavelength above ground and sometimes less.

I wanted a NVIS antenna that was portable, easy to set up, and cheap (of course). As it turns out, I had practically everything on hand. For my NVIS antenna, I started out with my 2 meter mag mount for my car. Then it was just a matter of attaching a quarter wave wire to the mag mount, then just string the wire horizontally from the mag mount to a tree, or a pole of some sort.

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How To Build A Portable 6 Meter Full Wave Loop For POTA / SOTA Activations

I have been doing POTA activations for a few years now. its great fun and encourages us amateur radio operators to develop off-grid communications systems. If you haven’t heard of POTA, its a somewhat new thing in the world of ham radio. The best thing you can do is go to their website to get the whole scoop. Its parksontheair.com.

One band that seems to be forgotten, not only in Ham Radio in general, but also in the POTA world. Sadly, the 6 Meter band is open sporadically, but few people really check on it. There is however a nice website, pskreporter.info that monitors various digital modes on all of the ham bands. Whenever I go out on a POTA activation I check the activity on the 6 meter band for activity, especially in the spring through mid-summer.

One thing though, since this 6 Meter Full Wave Loop doesn’t have high gain and a typical POTA activation often times doesn’t have a high location, that means that POTA on 6 Meters is much more of a challenge than the more commonly used bands. So when I go to pskreporter.info, I make sure the map shows a lot of 6 meter signals across the United States. If so, odds are pretty good that I will snag at least a couple of QSO’s on 6 Meters. One thing I have been doing on 6 meters is the FT8 mode. This is because the FT8 people are by far the most active on the 6 meter band. One time I got all 10 QSO’s needed to activate a park on 6 meters alone using FT8.

Here is a photo from the first time I used my new 6 Meter full wave loop . You can’t see the wires of the loop, but you can see the orange spreaders for the sides of the loop. I made ten 6 meter QSO’s that day on FT8 – I was pleased.

Build a portable 6 meter full wave loop for POTA

To build this portable 6 Meter loop, you first need to know how long to make the loop. The formula for calculating how long to make the loop is as follows:

Total Length (in feet) = 1005 / Frequency (in mHz)

In my case, I was mainly interested in the SSB and the FT8 portion of the 6 Meter band. So for my calculations I used 50.2 Mhz which gives me 20.2 feet. Or 5.05 feet per side. Since its always easier to make the wire long and trim, I made my wire 20.5 feet. As it turned out for me, that was too short and I had to add wire anyway. As usual, your mileage may vary.

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My First POTA Activation With The QRP-Labs QCX-mini Transceiver

I have been doing POTA activations for a few years now. its great fun and encourages us amateur radio operators to develop off-grid communications systems. If you haven’t heard of POTA, its a somewhat new thing in the world of ham radio. The best thing you can do is go to their website to get the whole scoop. Its parksontheair.com.

So in planning a vacation with my daughter, I wanted to do POTA activations however there wasn’t going to be any room for my regular POTA gear. This “required” me to look into a new rig. Lo and behold, i stumbled on to QRP-Labs’ QCX-mini transceiver. Man is it tiny! It measures 3 3/4″ x 2 1/2′ x 1 3/4″. Don’t let the size fool you, this thing packed with all kinds of features!

The QCX-Mini Features

Easy to build, two-board design, (if you are an experienced builder) board with main circuit and connectors, display panel board with LCD; all-controls board-mounted on a press-out sub-board. No wiring, all controls and connectors are board-mounted.
Professional quality double-sided, through-hole plated, silk-screen printed PCBs
Choice of single band, 80, 60, 40, 30, 20 or 17m
Approximately 3-5W CW output (depending on supply voltage)
7-14V recommended supply voltage
Class E power amplifier, transistors run cool…
7-element Low Pass Filter ensures regulatory compliance
CW envelope shaping to remove key clicks
High performance receiver with at least 50dB of unwanted sideband cancellation
200Hz CW filter with no ringing
Si5351A Synthesized VFO with rotary encoder tuning
16 x 2 yellow/green LCD screen
Iambic keyer or straight key option included in the firmware
Simple Digital Signal Processing assisted CW decoder, displayed real-time on-screen
On-screen S-meter
On-screen real time clock (not battery backed up)
Full or semi QSK operation using fast solid-state transmit/receive switching
Frequency presets, VFO A/B Split operation, RIT, configurable CW Offset
Configurable sidetone frequency and volume
Connectors: 2.1mm power barrel connector, 3.5mm keyer jack, 3.5mm stereo earphone jack, 3.5mm stereo jack for PTT, 3.5mm stereo jack for CAT control, BNC RF output
Built-in test signal generator and alignment tools to complete simple set-up adjustments
Built-in test equipment: voltmeter, RF power meter, frequency counter, signal generator
Beacon mode, supporting automatic CW, FSKCW or WSPR operation
GPS interface for reference frequency calibration and time-keeping (for WSPR beacon)
CAT control interface
Optional 50W PA kit
Optional aluminium extruded cut/drilled/laser-etched black anodized enclosure

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How to Run Winkeyer on a Raspberry Pi computer

Being a Ham Radio operator that likes CW (Morse code) and contesting, it helps to have a programmable keyer that will get text from a computer. In my search, I found the Winkeyer USB by K1EL Systems. There are several variants of the Winkeyer that include kits as well as fully assembled keyers. In this post, I will show you how to run Winkeyer on a Raspberry Pi computer.

Most logging programs have some way to send a pre-set string of characters to your rig, such as “CQ CQ CQ FD DE WB8ERJ WB8ERJ FD AR”. which is fine however when running CW at any speed faster than say 13 WPM, the computer is prone to timing problems and your CW comes out like you have terrible CW skills. This is because sending Morse Code that is generated by the computer has timing problems – especially in a Windows environment!

So by using the Winkeyer instead of the computer to key the transmitter, the task of actually generating the Morse Code is off-loaded from your computer, and your Morse Code is sent perfectly.

I have used Winkeyer with N3 FJP‘s contest logging software and it works just fine with that logging software, and I am sure many others. But there is a problem, I rarely run Windows computers and usually run Linux on a Raspberry P i computer. Specifically an install package by Jason, KM4ACK. Now this particular install package is targeted to portable / off-grid Ham Radio Operations. Since I have been doing POTA acvitations, Jason’s setup works great, and I highly recommend it.

So I needed a way to run Winkeyer in the Raspberry pi. On K1EL’s site there is this page that mentions winkeydaemon. Which is the answer to the problem. However not being completely fluent in the world of Linux, the task was a bit daunting. Maybe its just me and my lack of Linux knowledge, but I found the documentation to be rather difficult to follow.

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