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 an SASE.

Tuesday, January 1, 2019

The SOTA Cluster - Integrating SOTA 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:  elgur.crabdance.com; 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 display.

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 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 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. To do that you just connected 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 in order to watch for new band countries. and QSY the radio to the spotted frequency. 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. Since Ham Radio Deluxe is a dedicated stand alone program for controlling radios, you might even want a third serial port for that in order to be able  to run it and keep DxLab open for logging and spotting. 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. Then you don't have to worry about which programs happen to be open. They could all be open and it wouldn't matter.  (The only program I've used that doesn't play nice is WSJT-X for FT8. I run it on a virtual port, but cannot have any other rig control programs open while it is running.)

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 programs is set to run on one of those virtual ports and all three programs can run simultaneously. Below is a screen shot of the setup menu. You simply identify the physical port you want to split and create the virtual ports that your programs will use. Your computer treats these virtual ports as if they were physical ports. They even show up in Windows Device Manager. 



Thursday, December 13, 2018

160 Meter Shunt Feed 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.

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 and 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...






Friday, September 1, 2017

10 Essentials for Hiking in Colorado -- High Altitude Mountaineering Tips

I live part time in Buena Vista, Colorado, at 8,000 feet in the heart of the Rocky Mountains. Over the years, I have hosted quite a few visitors who want to experience the high country, or even try a 14er ascent and I have successfully guided quite a few group ascents.  Since 2013, I have climbed over 200 summits as a participant in the SOTA program.What I have learned from this experience and from taking the High Altitude Mountaineering Course at the Colorado Mountain Club is that the Colorado high country is like being on "another planet", with its own set of rules. Common sense rules we've learned at sea level don't apply here and, in fact, can put you in danger. Skeptical? Check out Alferd Packer (click the link). You don't want to end up like the Donner party! Or, for a more recent update, checkout the September 17, 2017 headline of the Denver Post - 11 Deaths This Summer.

I can remember my first 14er ascent in the summer of 1973 of Longs Peak, shortly after moving to Colorado from Illinois. I wore shorts, a tee shirt and carried a pint of water. For the 16 mile round trip, I started at about 7 am. When I finally made it back to the car at 8pm, I was dehydrated and suffering from hypothermia. Quite a powerful and memorable introduction to high altitude mountaineering! Fortunately, I was young and prepared to learn lessons the hard way.  That's not the case now.

The purpose of this post is to provide some basic guidance and encouragement to activators who want to visit Colorado and enjoy the back country without the sort of mishaps that rookies often encounter. By applying these rules, starting modestly, and gaining some experience, there;s no reason why your hard earned SOTA skills can't be applied in this "alien" world. 

1. Extra Layers

 As you ascend, the temperature drops about 3 degrees for every 1k feet of elevation gain. If you start in Denver and drive 1 hour west to Bierstadt and hike up, you can expect the temperature to drop 40 degrees (or more). Tourists don't get it. It is amusing to visit Pikes Peak and see tourists in shorts and tee shirts shivering their butts off in 40 degree howling wind and flurries after driving up from Colorado Springs where it's a balmy, sunny 80 degrees. I hike in a poly tee shirt, a long sleeve shirt (or turtle neck, depending on the season), a puff vest, and a shell (with under arm vents). Wind can be fierce, especially above timber line, so a shell is essential to keep out wind and moisture. My pants are poly, and my hiking boots are gore tex. In the winter, I often add an extra layer. Avoid cotton, which retains moisture. Remember, there is no such thing as bad weather, only poor clothing choices.

2. Start Early
Horseshoe Mountain, Mosquito Range, Colorado at Dawn, 13,905'

The mountains create their own weather. In the summer, the pattern generally starts with a perfectly clear sky with clouds building up gradually as the day progresses. Thunderstorms with lightning typically occur in the early afternoon, after 1pm or so. It's a good idea to be back to timberline by 1pm. After my youthful Long's Peak debacle, my next summit of that peak included an overnight above timber line. When I woke up at 5am for my final ascent, I saw headlamps coming over the ridge. The experienced in and out hikers had started their trip at 3am and chosen a full moon to do it. I now consider dawn to be the latest time to start a 14er ascent. Earlier if the approach is a long one. Hit the trail at the break of dawn.

3. Food and Water

Water is heavy and it is tempting to skimp on it, but that can be a big mistake. You want to stay hydrated to keep your body and mind functioning well, and you want some extra water, in case things go wrong. As a general rule I recommend a minimum of one liter for every four miles, but more is better if you can handle the weight. I recommend the Platypus bladder system. I also carry extra water in the truck and drink a liter before I hit the trail - and it's there if I run out on the way back.  Throw some food in the pack. I carry a few extra energy bars and a sandwich. It's OK if you don't eat them. But, you may need them. It's not good to hit the wall for lack of food or water. Colorado has low humidity. This dryness which increases with elevation sucks water from the body. Avoiding dehydration at high altitudes requires regular hydration. Don't wait until you are thirsty - that's too late. Hydrate at regular intervals. The first thing to think about if you feel dizzy or have a headache is dehydration. 

4. Personal Locator Beacons, 2 Meter Radios,  and APRS


Thinking about some worst case scenarios, I began carrying a PLB. I hike alone about 90% of the time. Much of that time I am bushwhacking in remote areas with no cell coverage and low likelihood of encountering another person. If I am injured and cannot walk out, I need a way to let people know where I am. This 4.3 ounce PLB takes care of that. I also carry a VHF/UHF hand held ham radio. Colorado has great APRS and repeater coverage, so I can spot myself using APRS, or use it to message my status back home. I can even let SOTA chasers follow me up the mountain just by turning of the location beaconing as I ascend. I often grab a few VHF contacts on 146.52 at the end of an activation. With these two lightweight devices, I can call for help if I need it, or communicate with family and friends when I am out of cell coverage. Be prepared to communicate in the event of an emergency and no cell coverage. If you are in the backcountry and don't have a ham license and carry a handheld 2 meter radio, you are missing out on a fantastic free public safety system. The same system that Amateur Radio Emergency Services use. 

5. Map and Compass

When I started out, that literally meant a map and compass. Today, for me, it means my iPhone, Gaia app, and Google Maps app. Todays cell phones have built in GPS receivers and, with a little planning, they work fine in areas with no cell coverage. I simply download a coverage map to my phone from Gaia and Google Maps in advance of my trip. Learn to read topo lines and follow them and learn your hiking speeds (up and down) so you can estimate travel times accurately.  Prior to a hike I derive a parking spot from Google Earth and lay down a waypoint in Gaia. I use the Gaia coordinates as a driving destination in GMaps. Most of the pre-trip planning I do is consumed by determining where to park and begin the trek. In Colorado, it's also important to descend the same way you came up. After an activation, in a rush to get down, it's easy to pick the wrong descent line and find yourself stuck in a ravine. Many Colorado search and rescue operations can be traced back to a hiker taking a "short cut" whether intentional or unintentional on the descent. Don't just "fall off" the mountain, follow the proper descent line. The easiest way to do this is to record the ascent and follow the same line of the descent. One other tip. I also wear a compass watch and take a bearing on the summit at the start of a hike. If all else fails, I can follow that bearing down. I also mark the car with a waypoint before ascending (I learned that lesson the hard way.) Don't lose your way.

6. Flashlight and backup phone/gps battery
I know you don't "plan" to hike in the dark. But if you find yourself in the backcountry after dark without a flashlight, it's not fun - it's dangerous. I carry a "lipstick" backup battery for my iPhone, that also serves as a flashlight.  If you are going to rely upon a smartphone for navigation, as I do, you must carry a backup battery. Don't get caught without power and light.

7. Strike Ignitor
Not only does the temperature drop with elevation, it also drops 30-40 degrees when the sun goes down.  In the event of an unplanned over night stay in the wilderness, this will allow you to stay warm and survive until morning.    Be prepared to start a fire.

8. Sun Protection



At higher altitudes, a thinner atmosphere filters less UV radiation. With every 1000 metres increase in altitude, UV levels increase by 10% to 12%. Unprotected skin at high altitudes burns fast. That's the primary reason why Colorado has the highest incidence of skin cancer in the country. Precancerous actinic keratosis is extremely common here. Many Coloradans visit a dermatologist each year for a check up and come home with arm, leg, face or scalp bandages from AK removal. You really have two choices, slather your skin with sun block or cover your skin with long pants, long sleeves shirt, and a wide brim hat to protect your scalp, neck, ears and nose (a ball cap won't cut it). I prefer the latter, with some clear zinc oxide sunblock on my nose and ears. Protect your skin.

9. Medication



The most common medical problems I have encountered on high altitude hikes are foot blisters, altitude sickness, and aches. Foot blisters are generally the result of poor footwear choices, bad fit, or inadequate break-in time. All of these can and should be identified and corrected prior to hitting the trail just by wearing the footwear for a week or so at home and taking some long walks. Carry some moleskin. Don't underestimate the misery you can inflict on yourself by failing to heed this advice!

The air is much thinner up here and it takes some getting used to.  Fewer than ten percent of people visiting Denver get altitude sickness. That jumps to 35% when once you get up around 10,000 feet and increases with elevation. The most common symptoms are dizziness, nausea, headache, loss of appetite, and insomnia. I've observed it first hand on several occasions, and it's alarming. Altitude sickness can often, but not always, be avoided by spending more time acclimating in Denver before heading up to higher altitudes. There is a lot of randomness associated with this reaction. Just because you get sick once, doesn't mean you will the next time, and just because you've never been sick doesn't mean you won't be in the future. So, it's best to be prepared. Ibuprofen has been shown to be an effective treatment, and it also has the benefit of treating the aches and pains that often accompany strenuous hikes. Taking ibuprofen before hand is probably a good idea. For more severe symptoms or as a prophylactic,  doctors often prescribe Diamox (or another similar drug). If you won't be spending a few days acclimating, it's good to have some Diamox handy, just in case. Just call your Doctor and let her know your plans and concerns and fill the prescription before your departure. Diamox is not an over the counter drug.

10. Trail Etiquette




Most regular Colorado hikers know and observe trail etiquette. You should, too. Here are some key aspects of good trail etiquette:

  • Uphill hikers have the right of way. Stand aside for uphill hikers so that they can maintain their  rhythm and momentum.
  • Leave no trace. Don't discard anything. Pick up trash if you see it. 
  • If there is a maintained trail, don't hike off trail, especially above timberline. Erosion is a problem with all trails. Maintenance is expensive and time consuming, so respect the mountain by staying on trail. Above timberline, the alpine tundra is very fragile. I can't stress this too much. Researchers estimate that Colorado alpine tundra already damaged by human activity will require hundreds of years to fully recover. 
  • Make eye contact with passing hikers, be friendly, and say Hi. That's the Colorado way!
  • If you are setting up a SOTA station at the summit, position it so that it doesn't interfere with other hikers and be ready to demonstrate and explain what's happening. 

Sunday, July 2, 2017

A Low Cost Emergency Personal Locator Beacon (PLB)

For the past two years, I have been hiking with a personal locator beacon in my pack. My ACR 2880 PLB is a 130 gram weight transmitting device that is registered with the Search and Rescue Satellite Aided Tracking System operated by NOAA. For details about this system and how it works, click here:http://www.sarsat.noaa.gov/sys-diag.html


This device differs from the Spot and DeLorme devices in several respects. First, there is no subscription cost. You just purchase the device, register it online with NOAA, and renew every two years online (I put a tickler on my calendar). The battery lasts 5 years. After that, the device has to be returned for refurbishing and recertification. The is a transmit only device designed for one time use. To activate, simply deploy the antenna and press the on button. When activated it sends out two beacons; a five watt distress beacon on 406MHz and a 500mw homing beacon on 121.5 MHz (for the S&R team). The distress beacon is picked up by LEO's as well as geostationary satellites and forwarded to local authorities with personal identification and location information. 

I am primarily a solo hiker, about 90%. I am often bushwhacking in rough terrain. If I am seriously injured or come across an emergency situation, I know that as long as I have a clear view of the sky.  I can quickly summon help, even if I am in a low spot with no cell or repeater coverage.

Fortunately, I have never had to activate the device except for occasional testing to ensure it is still functioning. However, it has provided a lot of peace of mind for me and my XYL, especially when I am activating in unfamiliar and remote areas. 

This system provides world wide coverage and is supported by a number of countries other than US. Check for suitability in your particular country. 

More information on the ACR 2880 can be found here:ACR 2880




Friday, May 26, 2017

EFHW Tri-Band Trapped 17, 20, 30 meter Antenna

Tri-Band SOTA EFHW 


I couldn't do any SOTA activations recently due to work commitments, so I spent some spare time building half a dozen unun's on different cores and comparing them to the Par and Packtenna efhw unun's both on the bench and in my backyard. I came up with a design that works well on my bands of interest, 30, 20, and 17 and doesn't require a capacitor. It uses a FT-82-61 core with a 16:2 winding for a 64:1 impedance transformation. My tests confirmed that a 9:1 unun is adequate to bring down the impedance into a range suitable for use with the Elecraft KX2 internal tuner. One advantage of using a 9:1 with the KX2 is the flexibility of using the antenna as a random wire on other bands where a 64:1 impedance transformation would produce a very low impedance/high current situation for the radio which could result in overheating or inability to find a match. However, I wanted something that I could also attach to a radio without a tuner, such as the LNR MTR3, which requires a low SWR.  I use 10 feet of thin rg174 as a feed/counterpoise, so I didn't want high swr for that reason, as well. My 17 and 20 meter traps are made from the SOTAbeam pico trap parts. Below are the plots of my final design. Plots are with the actual trapped tri-band EFHW. M1, near the top left corner of the chart gives the reading of the frequency under test and the resulting SWR. Green plot is SWR.The SWR's on a recent Dick's Peak activation matched these plots closely. The SARK 110 was indispensable during this project.


        Below: 30m, 20m, 17m field derived plots











Below - Also tested, Clockwise from left: T60-2 (red), FT-114-43 split winding, , NXO-100, FT-114-43 traditional winding.








Final Unun  - FT-82-61 (16:2)
end fed half wave transformer unun
SOTA EFHW UnUn 64:1 transformation



Saturday, May 6, 2017

SPE Expert Amplifier LCD Display Dimmer

I love my SPE 1.3K-FA amplifier, but the LCD panel is too bright and can't be adjusted. I looked around on E-bay and found some 3M film which I cut to size and placed over the display. It looks much better. The cost was $2.49 for a 4x6 sheet. I traced the display window onto a piece of paper, placed the film on top and cut to size.

3M Color Stable 35% VLT Automotive Car Truck Window Tint Film Roll Multi Sz CS35

Thursday, April 13, 2017

Antenna Alchemy - End Fed Half Wave Antenna and The Way of the Goat

drawing de DL3TU


Sota Mountain Goat is an award for accumulating 1000 activator points from mountain summits (see post). At least in Colorado, many of the winter activations are harrowing experiences in cold weather, deep snow, and high wind. Since it's not always practical to "hang around" at the summit the speed to set up and tear down can be critically important. No one wants to invest extreme energy and time climbing a mountain for an activation a descending with nothing to show for it. So, quick deployment and effectiveness are the watchwords for the kit.

When I first started SOTA activations, I looked around at what other, wiser, Goats were using in their kit and tried to copy them. I favored the lighter weight alternatives - no heavy radios, batteries or antennas for me. Aside from the transceiver, and mountaineering gear, the antenna stands out as the most important element of the system. I noticed that most of the Mountain Goats were using the End Fed Half Wave, or EFHW for short. While I had never previously used one, I thought I knew just about everything I needed to know about them. After all, isn't it just another flavor of vertical...? I was wrong. What I discovered shocked and intrigued me, as I think it will you, too.

At first, I was a bit confused about the difference between a random length end-fed, and the EFHW. The terms seem to be used interchangeably. Some of the articles I read had charts that showed lengths to avoid when cutting so-called "random length" wires. Turns out that if you randomly cut your random length wire to one of the "forbidden" lengths, it won't match, even with a tuner, and the SWR losses will be high. So, I initially avoided them. Only later did I learn that those forbidden lengths happen to be the half wavelengths or HW part of the EFHW, and these lengths are where some magic happens.

The Sota Goats don't want to dilly dally at the summit in dicey weather. They often need to set up, work their quota and get down. So, they don't have time for the one thing that we are all told we absolutely need in order to make a vertical work efficiently - radials. They need to extend a pole, string a wire, attach it to the radio and get on the air. The fastest way to do that, and put out a decent signal too, is with the EFHW - an antenna with a forbidden length.

The problem with the EFHW, the reason that it is "forbidden", is that it has an outrageously high feedpoint resistance at resonance - on the order of 3000 ohms. This is not a number that is friendly to any radio and it is outside of the range of typical matching devices. However, it is the high feedpoint resistance that is the secret of its success. Tame it and it will serve you well.

Why is the high impedance that we've been told to avoid actually an advantage? To answer that, let's examine the characteristics of a cousin of the EFHW that we are all familiar with, the quarter wave vertical. The radiation resistance of the quarter wave vertical is about 36 ohms. In a typical installation (4 or so radials) the ground resistance can be substantial - let's say 42 ohms for the sake of illustration. So the antenna presents a decent match to 50 ohm coax of 36 plus 42 ohms = 78 ohms, a good match to 50 ohm coax. The efficiency of this antenna is calculated by dividing the radiation resistance by the radiation resistance plus the ground loss... Rr/(Rr + Rg) = 59%. About 40% of the power is lost in the ground system. The situation gets much worse, however, if only one or two radials are used. The ground loss will rise to perhaps 80 ohms or greater and the efficiency will drop to 25% or so. In other words, the 5 watt QRP radio lugged to the top of the mountain will radiate around 1 watt with one radial attached to a quarter wave vertical.

In a fixed station installation, reducing ground loss is simply a matter of putting down a lot of radials. In the field, this is not so practical. Instead of putting down more radials, one solution is to raise the feedpoint impedance, the reducing the current flow at the base of the vertical and the corresponding ground loss. So, compared to a quater waver vertical with a poor ground systems, the situation improves somewhat with the so-called end fed random wire when it is longer than 1/4 wave. The typical impedance of this antenna is around 500 ohms. The radiation resistance isn't typically any higher than that of a quarter wave vertical but there is less current at the base of the antenna and you can get by with fewer radials. Avoid the "forbidden" lengths (43 feet is a popular length) and it works well with a 9:1 unun. A matching device (tuner) is generally required.

Now let's look at the EFHW. At resonance, the feedpoint resistance is approximately 3500 ohms. Consequently, there's even less current at the base of the antenna, obviating the need for radials. So, with just a short 3 foot counterpoise this antenna should be as efficient as a half wave dipole, making it ideal for quick deployment. Used with traps or jumpers a tuner is not required. SWR of less than 2:1 at resonance is typical with a 64:1 unun (16:2 winding ratio). Refer to the posting for instruction on how to build one.

But there has to be a catch, right? Otherwise, everyone would be using these cheap and simple antennas instead of quarter wave verticals. Well, yes, but most of the limitations just aren't very relevant for QRP in the field. Here are a few of the characteristics and limitations of the EFHW. There aren't any deal breakers on this list for SOTA work. The reason that this antenna isn't more popular in fixed stations has to do more with impedance matching issues than anything else - the popularity of coaxial cable for transmission lines and the lack of good high-efficiency unun's made it impractical, until recently. Broadband unun's with high transformation ratios are still largely the stuff of experimenters - but the experiments have been promising. So, have at it.
  • The EFHW can be built for multiple bands by installing traps or jumpers. I use an EFHW built for 40m with a jumper to shorten it for 30 meters. It works well on 40, 20, 10 with the jumper inserted, and on 30, 17/15 with the jumper open. SWR is 1:1 on the half wave frequencies, and matchable with the KX2 internal tuner on the multiples. I have recently built a trapped antenna with good results.  
  • Ground losses increase off the resonant frequency and efficiency suffers- cut it precisely for your SOTA freq.
  • While the feedpoint resistance of the EFHW is quite high, the radiation resistance is approximately the same as a half wave dipole, 73 ohms (the EFHW is essentially a half wave dipole fed at the end instead of the center). Though radials aren't required, ground proximity and other ohmic losses will adversely affect efficiency, depending on the average height of the wire above ground, and the efficiency of the matching transformer, traps, etc., in the system.
  • the impedance of the EFHW is too high for most matching devices (tuners). A 4:1 or 9:1 unun can bring it into range for most tuners. 
  • for a low SWR without a matching device, the antenna requires approximately a 49:1 unun impedance transformer (14:2 winding ratio) to match 50 ohm sources. It may be necessary to add a capacitor across the source for a match on the higher bands. I used a 64:1 transformer with success as described in another posting. 
  • A counterpoise with an ideal length of .05 wavelengths is recommended. Without a counterpoise, the coax and rig will create the counterpoise. This might be adequate, but if you can affect the SWR by touching the rig, experiment with the counterpoise. 
  • High impedance transformations can be tricky and inefficient. Don't assume your unun is lossless. Care should be taken in the selection of the toroid to avoid losses greater than 10dB. If possible, measure the power into and out of the unun to confirm the efficiency. 
  • Be aware of power limitations and do not overdrive unun's to saturation. Ferrite unun's can be permanently damaged by excessive power. In other words, QRP unun's are for QRP!
  • Commercial 50:1 unun's in various power ratings are only available from a few suppliers such as QRPGuys, and Pactenna (and high power MyAntenna unun's for base station use). 
In summary, a well designed EFHW is an ideal antenna for QRP situations where a fast deployment is required and center fed dipoles or verticals with radials are not practical. It has been analyzed theoretically and field tested extensively. It is so effective that it has won over many Mountain Goats who started out thinking otherwise. When you absolutely, positively have to set up very quickly and make at least four QSO's after hiking 5 miles to the top of a mountain, the EFHW is a good way to go. 





Sunday, March 12, 2017

Summits on the Air - Mountain Goat Award

When Heinrich Hertz proved the existence of electromagnetic waves, they were thought to behave like light (travel in a straight line), thus precluding the possibility of using them for long distance communication (more than 12 miles or so). Marconi thought otherwise. Over one hundred years ago, Marconi defied all expert opinion as well as common sense by proving that electromagnetic waves at certain frequencies will follow the curvature of the earth. He shared the 1909 Nobel prize in physics for this discovery. His technique was to use more and more power (up to 15 kilowatts), longer and longer wavelengths (up to 365 meters), and bigger and bigger antennas (huge wire arrays 100's of feet high) to extend the range of his signals,. On December 12, 1901 he successfully spanned the Atlantic "sparking" the electronics age we live in today.

SOTA activators on summits around the world. continue to stretch the bounds of Marconi's discovery of ionospheric propagation by using flea power, short waves, and small antennas to contact chasers thousands of miles away.

After 150 summit activations, about 3,000 two way contacts and 1000 activator points, I finally became a SOTA Mountain Goat. I just received this beautiful trophy from England which I will proudly display. This challenge entailed round trip signals to New Zealand, Spain, Japan and England from Colorado with 5 watts (the power of a flashlight) and 50 feet of wire! Here I am in contact with England from the 14,276 foot summit of Mt Antero (right photo).

Mt Antero in the distance
walton stinson walt