20m EFHW…Testing Complete

Here are the Transmit & Receive WSPR spots on 20m WSPR with the EFHW in full vertical configuration:

TX Spots

RX Spots

WSPR challenge website has had some issues but suspect that it would have scored about halfway down the list. I have been having some success in FT-8 contacts to Europe in the early morning which is more than I can say when using the S9V31+ vertical. Interestingly I am not seeing much from Asia particularly from Japan.

Working on some thoughts on how best to get a director wire setup about 10 feet away from this vertical. Looking forward to testing this out.

 

Slight modification to 20m EFHW

Checked on the EFHW just after sunset today and found the mast had just collapsed. I used the opportunity to move the end to the top of the mast which extended the whole vertical wire and brings the feedpoint up about 4 feet. I started running 1W WSPR just as the band died. Will collect data through tomorrow in this configuration.

So Many Antennas…

Still working towards a 20m beam of some kind for Field Day this year. The EFHW as a vertical has been working quite well by itself. FT-8 into Europe this week has been good the past couple of mornings. I made my first contacts into Finland and Norway using the EFHW. Turning this into a vertical beam is my next trick.

EZNEC models show that I can setup the director element to start at the same height as the driven element and just hang a bit lower on the other end. This leads me to think that a single support pole solution is feasible.

Extending this out a bit further, A 20m moxon as a vertical beam is much more compact and provides about the same amount of gain. My big question is whether the driven element can be an EFHW?

Easiest way to test is to start with the straight case on a second pole about 10 feet away from the driven element. Then I can play with bending the elements.

I am also looking at a major modification to a portable Magnetic Loop Antenna. Going to move to LMR400 as the loop as the stiffness should allow me to eliminate much of the support structure for a small loop anyway. Also looking at a design that uses a toroid for coupling such that it can be mounted along with the capacitor. Take a look at K1FM‘s take on this antenna.

Winter Field Day was Saturday??? – Doh!

Woke up on Saturday and decided to do some chores around the house that had been waiting for me. I finished up about 2:30 PM and turned on the radio to run some additional tests of resonant EFHW antenna. As I tuned the band, I realized that there was quite a bit of SSB activity on 20m due to Winter Field Day. I wasn’t really prepared but after a quick look at the event rules I started to work the event as 1H QRP.  I only worked WFD for about and hour but was able to make 13 SSB contacts using 5W. Most of these contacts were not difficult to make with only a handful reporting my signal at their noise floor. Nice performance on the EFHW as a vertical with only a very short counterpoise.

 

EFHW On the Air

I setup the EFHW resonant antenna on 20m a couple of days ago.  The radiating element is 32.9 feet of #14 stranded house wire. The counterpoise is about 3.3 feet of the same wire. I was targeting having the feed-point up about three feet off the ground but somehow messed up and ended up with the matchbox laying on the ground. Decided to run it that way anyway and correct later. I also installed a 1:1 choke directly on the feed-point to minimize any radiation on the outside of the coax shield. With this setup I went in and made a few SSB contacts with good success.

Running WSPR for 24 hours (transmitting 1W on a 20% duty cycle) I ended up with 115 unique spots recived and 134 unique spots heard. This is consistent with previous results and with some of the better antennas I have tested:

Spots Hearing NO5V

Spots Heard by NO5V

SNR vs Time of Transmitted signal

Interestingly I had no spots into Asia which may have been due to propagation but leads me to believe a good test of a beam will be to set the director to point into VK. I should overall see few spots since most of what I get are from the Northeast USA and should see signals into Asia. Will test soon weather permitting.

A EFHW Yagi Beam

I have previously done some work on End fed Half Wave Antennas (EFHW) of both the resonant and non-resonant types. I am wondering why the resonant type of EFHW is not used as the driver element of a Yagi beam? At least I have not found any discussion of this case. I ran a 20m EZNEC model and it looks feasible.

So here is my plan.

I am going to setup the 20m EFHW I built awhile back as a vertical. I’ll use the Spiderbeam pole for this so that the lower part of the 1/2 wave wire and matchbox is about 3 feet off the ground. I’ll use about 1m of wire as a counterpoise. I’ll do some testing on this as I expect it to behave as a 20m vertical dipole. I plan to isolate the feedline by installing a 1:1 choke at the feedpoint. I’ll collect some WSPR data and then setup as second Spiderbeam pole with a single wire about 1 foot longer and 10 feet away from the driven element. Modeling predicts that over average ground, I can expect about 5dBi gain at 15° elevation and a 137° beam-width with 12 dBi of front to back rejection. I’ll then run some additional WSPR and look for directionality among other factors and see if it works.

If this works, it would have the advantage of simple setup and no radials.

Using a NanoVNA to Measure Antenna Radiation Pattern

Found this article at RTL-SDR on someone who setup and measured a homebrew yagi’s radiation pattern using the NanoVNA. Pretty cool!

Netbook on 12V Power and GPS Time Setting

I have been working to use a Raspberry Pi for use in the field and the project is advancing nicely. Even so, I decided to pull out the Gateway LT4004u Netbook and my Dell E7240 Laptop and do some testing. I had discovered during field day the netbook drew a reasonable amount of power when run without the battery installed. The main issue I had that day was the connector I used to provide power would fall out with the slightest movement resulting in a lengthy reboot. During one reboot, Windows further decided it was time for an update of some sort as well. So today I replaced the connector and it works solid now. I am using a 12V to 19V Boost converter to run the machine off of 12V. It draws about .7A from the 12V supply while running with WiFi enabled. So that was sorted!

I started thinking about using the GPS dongle I am using on the Raspberry Pi on the Netbook and started down a rabbit hole. It was not as simple as using it on the Raspberry Pi. First off was a driver hunt. Found drivers at u-blox. Turns out that this little gizmo need two drivers installed: one is the VCP driver for the USB to serial and the other is the sensor driver for the dongle itself. Trial and error let me to installing the one for the port first then the one for the sensor. Once this was sorted I had to find some software that would read the time off of the GPS and set the netbook time with it. Turns out this is a bit rare but I did locate a program called GPS2Time from VK4ADC that works great. So now the Netbook (or any Windows based PC) can read time from the GPS satellites and set the system clock. Great when in the field and no internet is available. Here is the laptop running happily on 12V and reading GPS data:

As for the Dell…no such a great result power wise. I sourced a Dell connector which actually has three wires. Two are used for DC but the third provides and ID string to the laptop to verify that it is Genuine Dell charging. I wired the two power lines and as with the netbook powered it up without the battery. At boot comes a warning about the power supply/battery and that it will run at reduced performance. This was no joke as the Dell finished booting but ran slower than the Netbook! Not sure if I can resolve this somehow but looks like a show stopper. In this configuration it also consumed more current drawing 1A at 12V. So for now will be comparing the Netbook with the Raspberry Pi for field work. Windows vs. Linux as well.

Strange Periodic Noise on 20m

I have noticed that every time I make a change to my shack, in terms of equipment position or wiring, I will have some new noise problem crop up. I have noticed a clicking noise on 20m centered around 14.178 Mhz and 14.228 Mhz. Here is a sample:

I thought that this might be external at first. I had not installed a sense antenna on the Timewave ANC-4 noise canceller so I setup about 3 feet of wire around the back of my computer equipment. I was able to cancel out the noise completely with the Timewave. This tells me something is generating this signal locally. The only new piece of equipment since the remodeling was a USB hub so I’ll try that first.

Neil Peart 1952-2020

“No one gets to their heaven without a fight…”