Saturday, April 17, 2021
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.
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.
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.
Saturday, March 16, 2019
This is the description of the connector taken from the ebay listing:
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
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 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
Thursday, December 13, 2018
Thursday, March 15, 2018
|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.
- glue gun
- one 3.5mm stereo to 3.5mm stereo 1 meter cable
- perf board
- ear/mic or speaker mic
- heat shrink tubing
- 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
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 instructionsMeinberg 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.
Friday, September 1, 2017
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.
|Horseshoe Mountain, Mosquito Range, Colorado at Dawn, 13,905'|
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.
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
Friday, May 26, 2017
|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.
|SOTA EFHW UnUn 64:1 transformation|
Saturday, May 6, 2017
3M Color Stable 35% VLT Automotive Car Truck Window Tint Film Roll Multi Sz CS35