Sunday, March 24, 2024

Lightning Bolt Antenna Catalog and Quad Assembly Manual


The Lighting Bolt Quad was a very popular antenna until about 2005 when it went out of production. In my view, it was the very best value in an HF gain antenna. I have posted the assembly manual here for those who might have acquired a used one without a manual or those who might want to homebrew one with parts from MaxGain. 

I built and installed the 5-band, 2-element version of the Lightning Bolt several decades ago for $260. I really love this antenna. It was very inexpensive and it's been a good performer. Since I have another telescoping tower with a Kt34XA tribander, I have been able to do many A/B comparisons, and the quad performs very comparably with each at 40 ft (the max height for the quad tower). 

I have read some quad users state that one should feed each band separately. I chose not to do that after testing the quad with all bands tied together against the big tribander. The additional complexity didn't seem worth it since the quad was so close in performance to the larger antenna, I concluded that there wasn't much to gain with separate feed lines. However, I did add 30 meters to the quad with a slight extension described on my page at QRZ.com. 


Lightning Bolt Quad Assembly Manual

Lightning Bolt Antenna Product Catalog








Wednesday, December 27, 2023

Human Security for All - HS4A - IARU partners with UNTFHS and WAAS

 




Human Security for All is a global campaign of the United Nations Trust Fund for Human Security and the World Academy of Art and Science. This year, 2023, the campaign is partnering with the International Amateur Radio Union, IARU, to highlight the role that amateur radio can play in addressing Human Security needs. 

Human Security is a measure of security from the perspective of the individual. It is modeled around seven dimensions of security that describe our common experience in life: economic, health, food, environment, personal, community, and political security. These reflect our everyday life experiences much more personally than the security paradigms that focus on national security, but tend to get less attention. The pandemic, military conflicts, financial instability, and food crisis have each transcended national borders and demonstrate a profound lack of security at the individual level that needs to be addressed. . Human Security for All is a campaign to bring attention to these unmet security needs and stimulate the search for real solutions built around the needs of individuals. 

Radio means electromagnetic waves carrying information. The range of frequencies that produces these waves is called the electromagnetic spectrum. We know from the billions raised in spectrum auctions that frequency allocations are commercially valuable. Nonetheless, because they were there at the birth of radio and have played a critical role in its development, radio amateurs have been granted international parks of spectrum within which to develop, experiment, and utilize all manner of communications technology from digital to voice, from simple to complex, from local to global. These are called amateur radio bands, and they are spaced harmonically throughout the usable spectrum, each having its own unique propagation characteristics.

From the beginning, radio amateurs have utilized their skills to assist their communities and their nation with public service and emergency communication.   Recent disasters such as the hurricane in Puerto Rico and the earthquake in Turkey demonstrate the value of amateur radio with commercial systems fail or become overload with traffic. Amateur radio is often called upon to assist in fire fighting efforts where communications infrastructure is inadequate or non-existent. Amateur often step into professional roles to assist agencies in responding to emergency situations. Radio amateurs provide public service communications for special events such as races to monitor and support the health of participants. In the United States, the Amateur Radio Emergency Service (ARES) and the Radio Amateur Civil Emergency Service (RACES) are organized groups of licensed amateur radio volunteers who are trained to provide radio communications services to civil and government agencies in times of emergency. This model exists in many countries around the world. 

Today, radio is ubiquitous. To many, it has lost its magic. They forget it is the foundational technology of the cell phones we all carry. Our computer networking protocols, WiFi and Blutetooth are all radio systems. The internet service StarLink, is based on low earth orbit satellite radio pioneered by amateurs. Radio is still quite powerful and magical to amateur radio operators, but ordinary citizens take it for granted. If your station worked K4A in April 2023, go to clublog.org and request a commemorative QSL card. 


https://humansecurity.world/



Wednesday, May 11, 2022

Personal Recollections of Guglielmo Marconi



Walt Stinson, W0CP


Everybody wants to know about Guglielmo, now that he’s dead and all.  They want to know about our childhood together. That’s why I’m talking to you. I am going to tell you, and you can spread it around, and that’s it. I am done with it after I talk to you.  

Now, don’t get the wrong idea. It’s not that I don’t like talking about Elmo, because I do. It’s just that with him being the most famous person in the whole world, it’s been too much pressure. Too many reporters hanging around asking questions and my wife is getting on my case and I don’t blame her. I mean it’s not like they’re paying me or anything, and even worse they don’t know anything about it.  That’s why I’m talking to you. But yeah, I know the whole story of what happened, and since you’re into wireless and Morse Code, and all, I figure I can trust you to get it straight. 

People say he wasn’t smart because he never attended a proper school, but they’ve got it all wrong. Elmo was the brightest kid in the Village. His older brother, Alfonso, got his early schooling in England at Bedford.  Elmo and his mom lived there off and on till he was six.  He figured he’d get the same treatment as Alfonso and he was looking forward to it. But, no. He was stuck at the Villa Griffone and not even his mother could talk Don Marconi into letting him go back to England for school. You see, Elmo was bored out of his mind. Can you imagine being a teenager trapped at that Villa? I mean, it’s a really nice estate and all, but in his mind, it was a prison. His father didn’t even let him go to school in Pontecchio with the rest of us. Brought in tutors. Some kids would have rebelled, but Elmo didn’t. He respected his father too much for that. For the most part, he just accepted and made the most of it by trying to please his tutors.

Elmo and I were the same age. We made friends at church when we were 13 and played together all the time. He was a good horseman and taught me to ride, too. We rode around the Villa Griffone and just hung out talking about girls and science. We were both into science stuff, and girls just as much. He didn’t actually have a girlfriend, though, so the only thing that got him by was that he really admired his science tutor, Vincenzo Rosa, and wanted to impress him. Rosa told Elmo about everything that was going on with electricity in Italy, Germany, and England and kept him up on all the latest inventions like the telephone and how it was spreading around Italy and got him all excited about it. You see, Elmo figured we should keep in closer touch about stuff and we didn’t have any way to do it. He had to come into town and visit me or I had to hoof it out to the Villa, and it was really a pain. We wanted the telephone but it wasn’t in Bologna, yet. So, we decided to build our own telephone line from magazine articles and drawings that Rosa showed Elmo about what Bell was doing in America.  Anyhow, that never went anywhere because we found out how much it would cost and we didn’t have any money and Elmo couldn’t talk his dad into giving him the money for it. So, that plan was dropped. 

A few years later, Rosa took Elmo to meet a friend of his, Augusto Righi, at the University of Bologna. Righi and Elmo really hit it off. Righi told Elmo all about what Heinrich Hertz was up to. When we finally met up again, he had a new plan. We didn’t need any wires, he said. We would just use Hertzian waves to signal each other with Morse code. Righi sent Elmo some articles about Hertz’s experiments and we went to work on copying them. Elmo’s dad was down with it because it was going to be a lot cheaper than our first idea and because Rosa convinced him that it would be good for Elmo to experiment with this new breakthrough in physics. 

So, that’s how the whole wireless thing started. It didn’t matter to Elmo that scientists were convinced the waves would not travel very far. In his imagination, they could, and Rossa didn’t say anything to dissuade him from trying. 

When Elmo turned 16, that’s when he got a butler. His butler was named  Roberto Mignani. At first, Elmo didn’t know what to do with Mignani and vice versa, but when we started the wireless project, it finally dawned on Elmo that Mignani should be our assistant. I was kinda Elmo’s assistant too, so I guess he had two assistants, me and Mignani.  But, truth be told, I was actually Mignani’s assistant because he was really good. You really couldn’t expect much ingenuity from a butler but Mignani was no ordinary butler. He could make just about anything and if he couldn’t, he knew someone who could. So, when Elmo enlisted Mignani, that’s when things really got going. Hertz had detected a wave across the room and Elmo wanted to go further, so that’s what we did. We had all the details and copied the experiment and tried it out and it worked just like Righi said it would.

Elmo was very excited to see just how far the waves could go. You see, he had this idea about using Hertzian waves for signaling and connecting people over long distances.  Nobody else in Italy, Germany, or England cared a whit about communicating with wireless but it’s all Elmo focused on. We called it “the distance game”. We started at about 10 feet and went from there. Alfonso and Mignani were all in with our game. They thought it was fun, too. So, every week for a year we’d set up a new test to make a new distance record. Sometimes it wouldn’t work so Elmo would mess around with his equipment and try something new.  We tried putting the antennas up higher and that helped a lot. We tried vertical wires, horizontal wires, longer wires, and shorter wires to see what effect they would have. Vertical and longer were better. Then we hit the wall again and Elmo tried connecting a ground rod to the receiving and transmitting apparatus and that helped a lot, too. 

Finally, after a lot of trial and error, we set up the receiving apparatus in the field about a half a mile away, and Elmo’s brother, Alfonso, was able to detect our signal. Rossa and Righi congratulated Elmo on reaching “the limit”. You see, the famous English scientist, Oliver Lodge, had told Righi that one-half mile was the maximum distance the waves could travel and that’s what Rossa believed, too. But Elmo and I were playing the distance game and decided to push on until we couldn’t detect a signal anymore. Elmo didn’t care about what the scientists said. In his imagination, he was connecting the world and his messages could travel everywhere. 

Eventually, he got it working over a  mile. Way beyond what anyone thought he could do. That’s when he showed me how big he was thinking. He went to his dad with a bunch of ideas about how wireless could change the world. All he needed was more power, bigger antennas, and better equipment. In other words, a lot of money. His dad was impressed enough to introduce Elmo to some of Italy’s most important government and business figures, hoping to get him some backing. Elmo offered his inventions to the Italian navy, too. But, nobody in Italy was willing to back him. He got pretty discouraged. That’s when his mom suggested that maybe the Jameson’s could help him. 

Elmo’s mom, Donna Anne, being the granddaughter of the founder of Jameson whiskey, had lots of wealthy relatives in Ireland and England and figured one might be willing to sponsor Elmo. So, she took us to England where he presented his ideas to the family, the bankers, and even the British government. Of course, they all wanted a demonstration, which we gladly provided. By then we had the distance up to four miles. When they saw what we could do, some of them could see where things might lead and signed on to fund Elmo’s company, The Marconi Wireless Company. That was 1896. We were just 21 years old. 

Well, the rest of the story everybody knows. He kept on playing the distance game, breaking records every month. Elmo was always ahead of the scientists who had to play catch up and devise new theories to explain the impossible. When he broke the 12-mile barrier, the post office, the navy, and the bankers all got very excited as the possibilities finally became crystal clear. Then they said he couldn’t go further than 200 miles because of the curvature of the earth, but he proved them wrong again. Finally, in 1901, he made the first wireless contact between North America and Europe, spanning the Atlantic Ocean, making the front page of newspapers around the globe. Elmo’s fame was unparalleled which resulted in a lot of public adulation, including from the ladies, as he was still a bachelor at that time.  

Wireless would connect the world and usher in a new era of civilization, just as he had imagined, and the Marconi Company would be at the forefront. Elmo cleverly set it up as a service company. It didn’t sell equipment but instead leased it along with trained operators. Some of the first customers were the ocean liners because the passengers wanted to send telegrams but were totally out of touch for weeks at a time when at sea. When the Titanic disaster happened, without the Marconi operators aboard there would have been no survivors. The Marconi Company and its wireless operators were hailed as heroes and shipboard wireless was deemed a public necessity. More orders rolled in. 

Italy had long since recognized the importance of its native son and now it, indeed the world, poured on the honors. He was ennobled as Marchese by the King and elected a Senator. He was made a commander of the Navy. He was even awarded the Nobel prize in physics for boldly defying scientific convention and emerging a winner, which was a stunning accolade because he considered himself more of an entrepreneur than a physicist. I was not surprised at all by these accolades. Elmo relentlessly pursued his vision overcoming every obstacle. Radio communication was, by then, recognized as one of the most important technological advancements in the history of the world. 

Elmo was idolized the world over. Mothers and fathers of teenage boys encouraged their sons to learn the art and science of wireless. Given Elmo’s youthful appeal, it didn’t take much encouragement. Radio was an exciting game and its popularity exploded. Eventually, the boys made such a racket on the airwaves that some governments decided to crack down and create some order out of the chaos. There was even some talk in America about banning the unruly “hams” altogether, but Hiram Percy Maxim of the ARRL stood up against that.  Elmo, being friends with Maxim, backed him but wanted the hams moved up in frequency and out of his precious long-wave bands.  That’s what happened, and you know the rest of the story. The hams got lucky.

My life since those magical early days has been pretty dull, actually. I could have stayed with the company but I got homesick and returned to Pontecchio, got married, and settled down. I haven’t lost any of my excitement for radio communication, though. I am a ham myself, now. I have my own apparatus here at home and making shortwave radio contacts is my favorite pastime. Elmo and I kept in touch with each other through the years, often by radio. In fact, he installed a wonderful laboratory on his yacht, Elettra, and was playing the distance game right up to the end, exploring the potential of microwaves.

Now, let me pour you another drop of Jameson and I’ll tell you all about his glamorous girlfriends...


Friday, April 23, 2021

Optimizing the SunSDR2 for CW Operation

The SunSDR2 from Expert Electronics is a very powerful and flexible SDR transceiver package. The software that runs the show is stable and packed full of amazing features (like CW Skimmer integration built-in). While it performs well on CW, like most SDR radios it has a few issues with high speed CW >25 wpm.

The Sun utilizes semi-breakin CW with some nice customization settings. When using the built in keyer, the timing of CW character elements is excellent even at high speed, with no noticeable shortening of the leading element. However, it doesn't have QSK capability (the ability to hear between CW elements) because its T/R switching is not fast enough (QST measured 123ms).  While I would not place this radio in the top tier of CW performance, it is overall a very competent radio.  

However, there is one issue that I needed to address. When the internal keyer is turned off and the radio is fed with an external keyer, the first element in a Morse sequence is truncated a bit (noticeable only above about 25 wpm). Fortunately, this shortening can be corrected. 

The ExpertSDR software has a very cool transmit signal analyzer that can display the timing of Morse elements. At 30 wpm or so, you can clearly see the truncated elements. Using the built in analyzer, I was able to easily compensate for the shortening by adjusting the break-in timing. 

These are the settings I derived for the SunSDR2 Pro when using an external winkey:

  • On the ExpertSDR breakin tab, set the breakin time to 225ms or higher. (keep the rise time at 7 or higher to avoid key clicks!)
    • Play around with these settings a bit and observe the effect on the tx analyzer
  • Set the PTT delay to at least 10ms. (Longer will shorten dits and shorter is not advised). 
Below are before and after screen shots when using an external keyer. Note the shortening of some of the dits when using an external keyer. 

Click to Enlarge Image

Below is a screen shot after compensating for the first element shortening. Note the uniformity of the dits. 

                                

Saturday, April 17, 2021

A Simple 4 band EFHW for 40,20,15, and 10 meters

I like the EFHW for portable use because it is quick to deploy - unlike a quarter wave vertical, it doesn't require radials and unlike a dipole it's fed at one end. I have been trying out variations of the EFHW (end fed half wave) antenna for several years.These have included a 3 band trapped version (see post), a two band linked version, a two band lumped inductance version, and a fixed station 80-10 commercial version from MyAntennas.com. The later antenna is interesting because obviously the antenna is only a half wave on one band (in this case 80m). However, the 130 foot antenna is multiple half -wave lengths on all the other HF bands; 2 (half-wave lengths) on 40, 3 on 30m, 4 on 20m, 5 on 17m, 6 on 15m, 7 on 12m, and 8 on 10m. Interestingly, aside from the radiation pattern, the antenna behaves just like an EFHW on these other bands. It is resonant on these higher frequency bands with essentially the same high feedpoint impedance as 80m presents, resulting in a low SWR across multiple bands when matched with the transformer. So, let's call it an EFHW and just make the W plural = waves.

After getting good results with the MyAntennas 80-10 model at V31DJ, I got the idea to make a lightweight QRP 40-10 version of that antenna for SOTA and POTA activations. This antenna was cut for 40m, which is multiple half-wave lengths on three other bands; 2  (half-waves) on 20m, 3 on 15m, and 4 on 10m. The WARC bands, 30m, 17m, and 12m, can still be used, but an antenna tuner is required since this antenna is not resonant on these bands - it behaves like an end fed random length wire and needs at least one radial. 

In testing, the resonant frequency  of my 40-10 was high on 15m and 10m, so I added a small coil (6 uH) at 78 inches from the transformer to bring the resonant frequencies on these bands down to line up more with the CW SOTA frequencies. You can approximate this coil by cutting a one inch lenght of 3/4 inch pvc and winding 6 turns on this coil form. I put red self-emulsifying tape over mine to protect it. See photo. 

Below is a plot of the SWR. Note that the SWR at resonance is less than 1.4:1 SWR on all four bands, making it ideal for radios lacking a tuner like the IC-705 and QRP radios like the Mountain Toppers. 





FOC Tools for DxLab

Two files for use with DxLab are provided. One is a script file to be copied onto a filter tab in DxKeeper. This script will filter the log to show only Q's greater than or equal to 15 minutes for submission to the NewsSheet Quarter QSO's list. The other is a member list formatted for SpotCollector. This list, when loaded into the SpotCollector SpecialCallsigns folder will tag FOC spots with the member name and number if the spot source foc.dj1yfk.de:7373 is active in SpotCollector SpotSources configuration. This list is provided as an example. It will not be updated so it is up to the user to keep it current by editing the list. 

Click the link below to download the folder containing the two files. The size is <10k and it has been scanned for viruses. 

DxLab FOC tools


Saturday, March 16, 2019

Adapting the Elecraft KX3 and KX2 for two keys - two keys / paddles or paddle plus computer keying

The Elecraft KX3 and KX2 have two CW paddle inputs, individually configurable. This is great, especially for contest operations which typically require one input for the computer and one for a paddle. In this article, I'll describe how adapt the KX-3 for two separate CW inputs. 

I recently operated in the 2019 ARRL DX CW contest from Belize with my KX-3 driving an SPE 1.3k amp. This was the first time I've used the KX-3 in a contest or DX trip and I was impressed with its performance and features. Before this trip I didn't even realize the radio has dual watch, something the K3 doesn't provide as a standard feature. I used it when I was running pileups and it worked very well. This radio is really more than meets the eye.

Another great feature of the KX3 is two individually configurable paddle inputs. There's just one problem, the front panel header, Key2, mates with a non-standard connector for Elecraft's accessory paddle. To solve this I purchased the matching 4 pin header off of Ebay. The finished adapter, shown below, consists of a molded 3.5mm stereo jack wired to the header according to the wiring instructions provided below. To protect the header connections I put heat shrink tubing over the header pins. I used a hot glue gun and filled the tubing with a bit of glue and slid it over the pins. The hot glue shrunk the tubing somewhat and then I used a heat gun to fully shrink it. The finished adapter is shown below. The two key inputs can be configured for hand-key, or paddle. I configured Key1 for the computer (hand key) and Key2 for the paddle. The dot and dit pins are menu configurable, don't worry about getting them reversed. The wiring instructions (when viewing the radio pins) are as follows: Upper right=ground; Upper left=none; Lower right=dah; Lower left= dit.




The finished adapter cable

This is the description of the connector taken from the ebay listing:

2.54mm Pitch 2X2 4 Pin Female Double Row Straight Header PCB Connector 284

PS - I had to purchase 50 of these. So, as of this posting, I have plenty of surplus.  If you are reading this, I still have some. If you want one, FREE, just send me a SASE.       

Tuesday, January 1, 2019

The SOTA Cluster - Integrating SOTA RBN activator spots with Logging Software

This post is for SOTA activators and chasers interested in integrating SOTA spotting with a traditional logging program.  SotaWatch feeds the SOTA cluster system with manually posted spots as well as those picked up by the RBN (reverse beacon network) that match alerts previously posted on SotaWatch. This article describes how to tap into this system and feed these spots directly to a logging program. There are several advantages to this approach such as the ability to click on a spot to QSY the radio, have SOTA spots filtered or listed alongside DX spots, and keeping SOTA chaser QSO's in the main log (not running a separate chaser log). My logging program is DxLab, which I highly recommend. However, this technique can be applied to any logging program with a spot management feature allowing the use of multiple spotting sources.

To enable the cluster in DxLab launch the SpotCollector app and click on "Config", then click on "Spot Sources".  In the host address box enter the following address:  cluster.sota.org.uk; the port address is 7300; the caption is SOTA; the username is your callsign; and there is no password required.   (Thanks to Andy, MM0FMF, for providing this capability. )

If this is the only cluster enabled, only SOTA spots will display. In most cases other sources will also be enabled for DX sources as well. In that case, it is helpful to use some tricks to indicate the source and to filter the spots. The SpotCollector app has a column showing the Network from which a spot was obtained. Drag this column so that is will display on the page without scrolling. In my case, I put it next to the Freq column. To filter the display so that it shows only SOTA spots it will be necessary to set up a simple SQL filter. This is done by right clicking on a filter box. Enter SOTA in the caption column and enter the following SQL expression: (network="sota"). Now when you click on this box in the SpotCollector display, only SOTA spots will appear.

SpotCollector is a stand-alone app. This means that it can be used alongside a different logging program to watch for SOTA spots. However, it also integrates well with the other DxLab applications. There is no reason why the cluster cannot be used with other logging/spotting programs as well, with perhaps fewer filtering options, as long as those programs allow for manual configuration of spotting sources. In that case, simply enter the telnet address and port shown above.


Friday, December 14, 2018

Serial Port Splitters in Amateur Radio Applications


Serial port splitters are software utility programs that can turn one physical serial port into multiple virtual serial ports. When serial port splitters are being discussed, the first question asked is usually "why would I want to do that?".  To answer that, you need to know that serial ports can generally only be used by one program at a time. Let's suppose that you use DxLab software for logging and rig control. All you had to do is just connect a computer to the radio to read the frequency, log it, and QSY the radio when you click on a spot from the Dx cluster.  

OK, simple enough. But suppose you want to run another program at the same time and you want that program to also communicate with the radio. For example, you might want to enter a Dx contest and use a dedicated contest logger like N1MM and at the same time run DxLab SpotCollector in order to watch for new band countries. and QSY the radio to the spotted frequency. Or, you might want to run WSJT-X and a logging program at the same time. Well, now you have a problem. You shouldn't set two programs to use the same serial port, nor can you use a Y cable. If you do, both programs will try to communicate with the radio on that port and neither will work. What you need is a way to "split" the radio's serial port into two distinct ports so it can communicate with more than one program. You might even need a third serial port for an amp or antenna switch. Once you start automating the urge to expand is natural. Fortunately, it's very convenient to create a virtual serial port for each program you run that needs access to the serial port connected to the radio. Once a separate virtual port is assigned to each application you don't have to worry about which programs happen to be open before you open another. They could all be open and it wouldn't matter.  

That is basically a description of my setup. I have used the Eltima Serial Port Splitter successfully for several years to split a physical serial port (Com3 in my case) into three virtual serial ports (Com8,9,10). Each of my dedicated programs is set to run on one of those virtual ports and all three programs can run simultaneously.  You simply identify the physical port you want to split and create the virtual ports that your programs will use. Your computer and software applications treat these virtual ports as if they were physical ports. They even show up in Windows Device Manager. 

20210416...Update!!  I recently purchased an SDR radio. These radios generally do not have physical serial ports. Instead, they use a virtual serial port (on the ethernet connection) to communicate with software programs. That presents a problem for most serial port splitting utilities which can only split physical ports. That's the situation I ran into with Eltima. When I tried to split the radio's virtual com port the SDR's control program could no longer communicate with my logging program. Fortunately, I found a utility that can split not only physical ports but virtual ports, as well...Eterlogic VSPE (virtual serial port emulator). While this program requires a bit more geeking ability than some other solutions like Eltima, it is very flexible and powerful as well as very affordable at only $25 (try before you buy). Eterlogic is now my recommended solution and is an essential utility for SDR owners who want to split a virtual port. Eterlogic's VSPE allows up to 8 programs to utilize one virtual serial port. If you decide to try VSPE, here are a few tips to make things go smoother:
  • Click on the white space to create a split com port
  • Note that the port you want to split should be selected on the right side of the panel
  • The single virtual port you create on the left side can be used on up to 8 applications
  • Since you will want to run VSPE every time the computer boots up, you should make it a "Windows Service". Click the "helper" tab and follow the instructions. Be sure to run the Windows CMD screen as an administrator. 
  • You can download a trial version of VSPE and try it out before you buy. It is fully functional with this caveat: Windows Service cannot be set up. The program must be run manually. 




Thursday, December 13, 2018

160 Meter Shunt Fed Tower System - Vertical Antenna

I wanted to use my tower as a vertical on 160 meters. The tower is an LM-470D motorized 70 foot crank-up supporting a ten foot mast and the following antennas: KT34XA, 40-2CD, 3el 6m, and 80 meter quarter wave sloper This system is designed to allow the tower to be raised and lowered each day. The 3 foot metal stand-off arm is attached at the third level, approximately 50 feet fully extended, and the pipe is 15 ft long. The only purpose of the pipe is to stabilize the gamma wire so that it doesn't get tangled in the tower when it is raised or retracted. There are other ways to accomplish it, but this system is simple and has proven reliable over a 20 year period. If a fixed height non-retracting tower is used, the pipe is unnecessary. I mounted the omega match inside on the barn wall to get it out of the weather. Prior to moving it to the barn, I had it at the base of the tower, first in a tupperware style container and then in a heavy duty irrigation box. In both cases, I had to regularly deal with animals, insects, and moisture. It worked, but it was high maintenance compared to this system, which has been "no maintenance". There is about 100 sq feet of aluminum sheet tied to the base of the tower, which is earth grounded. Two 1/4 wave elevated radials are attached at the top of the first section, about 15 feet off the ground. These radials are not grounded and a tap wire runs from the radials to the top feed through insulator. This system has been in use in more or less this configuration for 20 years with about 120 DXCC countries confirmed through casual DXing on the Top Band. See photos of this setup at QRZ.com.

20210427 Update: Exploding Choke forces Conversion to L Match
Little is known about the risks of shunt feeding a telescoping tower for 160 but we have some anecdotal data indicating that care is needed. In my case, all was fine until RF decided it had to find a better way to the 40 meter yagi boom and or elements  at the top of the stack. This is just a guess, but perhaps the driven element of the yagi "wanted" to be integral part of the system? A problem then arises when large currents reach the choke, which is designed to block such current flow. You can see below what 1500 watts of shunt fed power on 160 meters did to the choke! Check out VE6WZ's you tube and blog posts and you'll find a similar story.  
click to enlarge

My options at this point were to install a relay to ground the driven element during 160 operation or to replace the choke with a proper high power balun and hope that it wouldn't arc. I decided to go for a new balun and chose the DxEngineering MC20 with the mounting hardware that's offered for it. Unfortunately, after installation the electrical length of the tower got shorter and I could no longer match it! We tried to find out why and even ran a wire all the way up connecting all the tower sections electrically, bypassed the balun, etc., but we were never able to determine the exact mechanism for the shortening after the new balun was installed. Now, my shunt fed tower was electrically short on 160! The Omega match will only match an antenna that is electrically long.  (I have read posts on-line by hams wondering why they can't match a short tower on 160 with an omega match. If you're thinking of doing this, it won't work.) The solution was to convert to the classic L match. This resulted in a perfect match. Six months of subsequent rigorous high power testing during contests has not shown any failure or deterioration of the system.


The L match mounted on the wall of the barn. 
The 2kw inductor is tapped at 7 uH and the capacitor is a 90-150 pF variable




Thursday, March 15, 2018

Adapting a Two Pin Speaker Mic to the Elecraft KX2 and KX3 (Kenwood, Baofeng, Pofung, etc)

Finished Portable Ear bud-Mic


Following up on the "no-weight microphone" post (below) is an adaptation of two pin speaker mics often included with VHF HT's and readily available inexpensively on-line. These mics have the advantage of a PTT (push to talk) button. Shown above is an ear bud/mic that was included with a Pofung HT. I chose to modify this because the Elecraft headphone jack has low output and I didn't want to hold a speaker mic to my ear during reception. However, this adaptation will work for with a Kenwood style speaker mic, as well as with the ear bud mic shown above.

Parts required:

  • glue gun
  • one 3.5mm stereo to 3.5mm stereo 1 meter cable
  • perf board
  • ear/mic or speaker mic
  • heat shrink tubing
Instructions:
  • Cut the stereo cable in half. Strip the ends and determine the color coding to the tip, ring, and sleeve of the plugs.
  • Cut the two pin connector from the ear bud mic. Leave 3 inches of cable with the plug. Strip the cable and determine the color coding for the tip, ring, and sleeve of each plug. These wires are tiny and cloth type, so put a dab of hot solder on the ends to make them conductive. 
  • Solder the wires from the ear mic in a row on the perf board and then match up the appropriate wires from the stereo cables in the adjacent row and solder them. Bridge the lands between the stereo cables and the ear mic with solder. Note that the speaker ground (sleeve on the small plug) will have two connections and that not all wires will have a connection. 
  • Test the assembly with you radio.
  • When it tests OK, use hot glue to affix the cables to the perf board, wihich provides strain relief. 
  • Slide a piece of heat shrink tubing over the perf board and shrink it to provide protection. 
  • Adjust the mic gain and compression on the radio to match the mic characteristics. 
  • Note: because ground is provided by the speaker plug, both mic and spkr must be plugged into the KX for this to work. If you want to use the KX speaker instead of the earbud,you must put the unused earbud plug into the aux jack of the KX to provide ground in order for the circuit to function.
    Hot glue for strain relief
    Wiring diagram for two prong speaker mic to Elecraft

Saturday, September 30, 2017

Tips for Operating the FT8 Digital Mode








The FT8 mode is taking ham radio by storm, and for good reason. Just as we were becoming despondent about entering the doldrums of the sunspot cycle, here comes a mode that can dig signals out of the noise and copy them Q5. The high bands, particularly 15, 12, 10, and 6 meters are suddenly capable of producing DX QSO's with regularity. It's miraculous.

I have been using the mode with great success to work new band countries for the DXCC Challenge award. In the process I have learned a few lessons. While the mode is actually pretty easy to master, there are a few things to pay attention to.

1. Maintain Accurate Timing. The shack computer cannot be more than a few seconds off official UTC, or this mode simply won't work. Its weak signal performance depends on perfectly timed transmission and reception sequences. My Windows 10 computer was set by default to automatically sync the time every week and that turned out not to be good enough. I have now got it syncing frequently, which solved my problem. To check your computer's accuracy bring up the clock in the lower right corner of the screen and watch it while listening to WWV. The long beep from WWV should occur exactly on the minute. Another way to check is to bring up the https://time.is web page, which will automatically display your time discrepancy.  See below for instructions on how to force your windows computer to time sync. The solution I recommend is called meinberg ntp.

2. Don't use a narrow filter. If you can control the filter bandwidth, open it up to 2.8 KHz or greater (except 60m, which is a special case). Also, if you are using SSB mode, make sure you don't have an equalizer turned on. My K3 has a digital mode that bypasses the equalizer and has its own mic input level setting. Check you manual to see if you have a similar setup to use instead of using the SSB mode.

3. Make sure your computer mic is off and gain is set correctly. I occasionally hear folks transmitting an FT8 and their mic is also on. That can be embarrassing! Watch your ALC and keep it below the threshold which is typically one bar (note that the Elecraft threshold is five bars) and by all means make sure you don't over drive the input and trash the frequency. Keep the power level down, too, to ensure a clean signal and a cool running final. Half of rated power, max, is a good rule of thumb. Remember, FT8 is a weak signal mode. There's no need to dominate the frequency with high power.

4. Read the excellent manual and watch some YouTube videos before you try to make contacts.Work a few stations before you try calling CQ. Here's a link to an excellent operating guide -- FT8 Operating Tips

5 If you need a USB interface to connect the computer audio out/in to the transceiver audio in/out, consider a Tigertronics SignalLink, MFJ 1204 or the RigBlaster plug and play control interface. I have also had success just using a Griffin iMic USB sound card dongle with a line input (most sound card dongles just have a mic input which is easily overloaded by the line level audio output of the rig). Just plug the dongle into a usb port, change your computer sound settings to default to the dongle, plug rig audio out into the dongle line input and plug the dongle output into the rig input. Adjust the settings to prevent overloading these circuits, and go.

6. If you are a DXer like me, learn to operate split using the waterfall display. FT8 doesn't handle simplex pileups better than any other mode. Uncheck the TX=RX box. Double click on the DX station callsign you want to work, then shift click on an open frequency on the waterfall display. Practice this technique when answering ordinary CQ's.

7. For more tips and shortcuts, go to the FT8 main screen and press F3 or F5.  Download WSJT-X here:  Clicky

8. While FT8 is semi-automatic, you can send messages manually by  un-checking the auto sequence box and clicking the TX numbered boxes. You can also double click TX1 to prevent it from automatically sending and put a contest exchange in TX5.

That's about it. This mode is easy and fun to use, especially for quick DX QSO's and weak signal work. It's fast, too. QSO's only take about a minute. It is bound to make its way into the SOTA world as soon as a lightweight external processor or phone app is developed.

Time Sync instructions

Meinberg NTP is the best solution I have found for time syncing in Windows. It is a free binary app without a windows interface that runs in the background as a "low overhead" service and calibrates my computer time as frequently as necessary to keep it exact. I have had it running for quite a while now and it has worked perfectly. Download here Meinberg NTP. If you want to customize monitor, or control Meinberg NTP learn more here MeinbergMonGuide.pdf

There are several other reasonably good options. Here are the instructions for setting up your windows computer for hourly time sync. The is also an app available called Dimension 4 if you aren't comfortable following these instructions or prefer a windows interface.

Make Windows synchronize time more often  Time Sync Instructions
https://www.pretentiousname.com/timesync/index.html
Make Windows synchronize time more often This page explains how to make the Windows network time (NTP) client synchronize its time more often than the default once per week. This was tested on Windows 7 but should work with Windows XP and above. Why is this important? I don't know about your machines but both my desktop and my HTPC have terrible clocks. They seem to drift by about five minutes each week and that messes up things like scheduled TV recordings or stating that it is 13:37 o'clock o...