I have been working on a USB-only interface for the Top Ten Devices DX Doubler for some time. I recently completed the 3rd generation prototype. This is still a prototype – it uses a very small Arduino board with attached wires, but it is shoved into a nice small Ethernet drop-box enclosue.
This version has been in testing for several months. I have tested one, and a friend, K7SV, has also been testing one. He is a much more active and accomplished SO2R operator than I, so his feedback has been very helpful and much appreciated – thanks Lar.
At this point, I feel this is a viable design and it seems to be reliable. The only issue known is that I have to recycle the 5 volt power on mine after a week or two of inactivity in my shack. Not sure why, and I know Lar has not had this problem. I am wondering if my PC is shutting-down the port.Recycling the power once always resolves the issue.
There a a couple photos of the latest prototype below.
This version uses a tethered DB25 connector that attaches to the DX Doubler box. The USB connector you see is for 5v power ONLY – this seemed like an easy way to power the device, but I am still experimenting with other power options. I need a version that uses 12vdc for my shack. I also plan to make the final unit capable of working with supplies of up to 15vdc, so it can be used in nearly any station, Home or Mobile. Notice the attached snap-on ferrite. I put these on nearly all of the peripheral devices in my shack, and especially in my Mobile. I have not had any indication that this is needed to combat RFI, so it is only a precaution. My antennas are too close to my rig, so I do not want to push my luck.
The RJ45 port seen in the lower photo is for connection a USB to Serial interface. This is the actual port that is used for communication between the DX Doubler and the PC. There is a standard USB–>Serial cable that is made for connecting to Cisco routers. I have opted to use this cable, which is available at Amazon for under $ 14. It uses the popular (though somewhat expensive) FTDI chip, which is known to be compatible with the N1MM+ software I use. With this cable connected, I can utilize all of the DX Doubler functions, including computer-generated PTT and CW keying. This design has been setup for use with N1MM+ Logger software. It should be compatible with other software that can use the DX Doubler but I have not yet found any testers to configure and verify this. I am in the early stage of trying the DXDUSB with WRITELOG software, another popular contesting application.
I have now turned my attention to designing a printed circuit board version, that will be enclosed in a small chassis, and could possibly be embedded inside the DX Doubler chassis as well. more on this later. I have received a couple inquiries about providing this as a product. That is my plan if there is enough interest. Sorry, but I am not yet ready to ship these in any quantity. I may be able to send a couple out for testing, but delivery time would be at least 2-3 weeks. Any additional feedback or questions would be welcomed.
I went mobile again for the 2016 Virginia QSO Party, using the callsign KT4KA. I use that callsign so as not to confuse everyone when calling CQ (with my normal “3”call). The goal this year was to beat last year, and hopefully win the Mobile all-Band category. No matter what happens, this is always enjoyable. It is a challenge assembling a usable HF Mobile station, and I get to see some parts of the State that I don’t often visit. Following is a summary of this year’s event, and some photos of the equipment.
This year I decided to take my newest radio, the Yaesu FTDX-3000 with me. It was not exactly made for the road, but I love the receiver in it, and it is much better on the low Bands than my other radio, the made-for-mobile Icom-7000. I also planned to use my two-radio controller, the DX Doubler in the setup. that did not exactly work out, but so it goes.
The map below shoes my route this year, as reported by the APRS system.
Day one – I started near Richmond and headed out toward skyline drive, making stops in the following Counties/Cities: Richmond City, Louisa, Orange, Rockingham, Harrisonburg, Shenandoah, Warren, and Fauquier
When I got to the entrance to Skyline Drive, I was told that it was closed due to snow at the high elevations. Not exactly what I had in mind, but I was in the higher elevations and was able to add on many VHF QSOs from that area. Nowhere near what I could have had on the Skyline, but that’s life.
Day two – I started in the Falls Church area, and worked my way to the west, toward my home in the Warrenton area. Stops were made in: Falls Church City, Fairfax, Fairfax City, Manassas Park City, Manassas City, Prince William, Loudon, and Culpeper.
Here is a shot of the Mobile antennas in the parking lot of The Stone House at the Manassas Battlefield Park. You can easily see the Hi-Q Antennas 4/80 HF screwdriver antenna. That did most of the work for me in VAQP this year, with 40m and 80m being the big Bands. there is a smaller antenna on the passenger side roof for 2m and 440 MHz.
The next photo is a shot of the Mobile station from inside the Ford F-150. You can see the Laptop, FTDX-3000 in the middle, and the Head unit of the IC-7000 on the left. The cell phone that is barely visible is showing the VAQP Spotting network hosted by QSOPARTY.COM. That is the brainchild of John, KX4O and it has become a widely used spotting system by FARA members and recently by many others. he software was, or course, N1MM Logger+. If you work contests and you are not using N1MM, you need to see what you are missing.
In the later hours, here is how it looked:
Overall it was a very enjoyable weekend. Band conditions were not good on Saturday, with VA stations barely able to hear each other on HF. I attempted to compensate by working more CW contacts, with the usual breakthrough ability of CW. I found a number of stations in several other Call areas that were willing to work me many times. Overall score was better than last year despite the Saturday doldrums. We will see how it all works out. The FTDX-3000 will be joining me on the road again next year. I just love the rig. I need to do some improvement on the antenna switching setup. I also plan to take a complete SO2R setup next year, with the DX Doubler.
As I try to continually improve my Station, I keep coming back to the antennas. I have a couple very nice Radios, but I am still not very competitive in Contests, especially DX contests. I have always used mainly wire antennas and generally if I can hear them, I can work them. Now I know the problem is that I can not hear enough of them!
I had an opportunity to work a Contest from a world-class Contest station (NR4M) recently. The contest was the ARRL International DX CW. I won’t go into the details of the antenna system there (you can search on NR4M), but let’s just say they have about 65 acres worth of antennas like I will probably never see anywhere else.
I had access to all kinds of antennas on all the HF Bands. One antenna group that really impressed me was on 80 meters. I heard all kinds of DX during the weekend and I even managed to work China on 80 meters. That will not be happening at my Home QTH any time soon. I was using two antennas at the time, in Diversity Mode on a K3. This was quite a new experience. The diversity did just enough to bring the China station’s signal out of the noise enough for me to work him.
So the lesson learned here is that if I really want to improve my station and get to the next level, I have to do something about the antennas. First project is going to be getting a yagi on the roof. I will always use wire antennas, and I will be trying to improve them as well. I recently installed a Beverage antenna for the first time. At a length of about 300′, it is not very long, but I am hoping it will improve my hearing ability on the Low Bands.
Of course another thing I could do is raise my Power to the KW level. I do not plan to do that, mainly due to the small lot I am on and the close proximity of my antennas to the Shack. I think going QRO would result in an RFI nightmare.
I plan to go mobile again this year for the VA QSO Party in March. This is an enjoyable contest with lots of activity. You will probably see every County and City in the State activated at some point over the weekend. I will be using the callsign KT4KA/M so as not to confuse people by using my normal “3” call KG3V.
I try to do something a little different every year for this Contest. This year I am going to attempt to take a complete SO2R (single operator 2 radio) station in my pickup truck. I have an ICOM IC-7000 permanently in the pickup and I will be adding my SO2R Controller box, the DX Doubler, and my FTDX-3000 for the HF Bands. Plan is to use the IC-7000 for mainly VHF/UHF. The SO2R controller allows me to work HF continuously and still hear anything that pops up on VHF/UHF.
I am still in the process of building the station. I had to completely rewire my HF antenna, a Screwdriver antenna from HiQ Antennas. All of my connections had corroded after 3 years of use with little maintenance. I also had to buy a new door mount for the VHF/UHF antenna as the feedline for mine had gotten cut in half by the door hinge.
Had one setback today. My homebrew USB interface for the DX Doubler was not working and it turns out the Arduino board (a Pro Mini) had died. So I replaced that and all seems to be working again. Still not sure what happened to the Arduino, but this was a $3 board. more proof that you get what you pay for, I guess.
If you are not a regular in VAQP, give it a try.
If you have been working with Arduino boards, you may already know about this great little board. The Arduino Pro Mini is about 1.7″ X 0.7″ in size. It has the normal 14 Digital I/O lines and several analog inputs as well. The one thing you need to know is that you must have a Pro Mini Programming Cable for this board. These cables convert USB to Serial I/O and provide a 6-pin header that connects to the Pro Mini when you are downloading or debugging.
Spark Fun is the designer of the Pro Min. There are also some “knock-offs” out there that are even less costly. if you look around, you can find these Pro Mini Arduino boards for under $ 5.00. These are great for an embedded project. I am using one to design a USB interface for my DX Doubler 2-Radio Controller box. It almost fits inside a D-sub connector backshell. I am using a small Ethernet port box to house mine. It makes for a nice small platform for various Micro Controller projects.
There are a few things to be careful of with this board. There are 3.3V and 5V boards, so you need the right voltage on your Programming Cable. The programming cable is also not cheap, but you only need one and they have a genuine FTDI chip, so they are reliable and very flexible using the FTDI driver and configuration software. Beware of cheap FTDI imitations. If you buy one, there is no guarantee that your FTDI driver software will work. There are also different pin-outs and different clock speed version available.
Pro Mini boards come with headers for the programming cable and the I/O pins. Some sell them already installed, others make you solder them in if you want them. They are easy to install, so this is no big deal. My one minor complaint is that this board has no mounting holes. That makes it a challenge to put into a chassis, but the board is so lightweight that you can use a cable tie or some double-sided tape to put it wherever you want to mount it.
I mentioned varying pinouts. If you are just using the Pro Mini on the bench, the only issue is that you may need to reverse the programming Cable on some versions. If you are planning to put an Arduino Pro Mini on a circuit board, you need to be careful to use the correct pinout for the devices you buy. I am currently using PCB123 to layout a PC Board and attempting to build a footprint that will be compatible with both pinout versions I have seen. This will let me keep my costs down by purchasing whatever version is the cheapest when I am ordering.
The pro Mini is a great little board. Buy a few and have some fun. You might be surprised at what you can do with them.
I just saw on the ARRL LOTW Web Page that they have processed my application for the ARRL Triple Play Award. I do enjoy Contesting but otherwise I do not spend much time chasing awards. The Triple Play Award, if you don’t know, is for confirmed contacts with all 50 States on CW, Phone, and Digital modes. I like to bug other Hams to get on the Air and make some contacts. This shows I am at least making an effort to use the Bands and try the various modes. I will be glad to have this award hanging on my Wall. Congratulations to the other 1,747 Hams who have received the Triple Play award.
The 2nd prototype of the DXDUSB Interface has been completed. I ran it hard through the recent NAQP CW contest, and it did very well. Now it is just a matter of finalizing the software (of course software is never really “final”). Here is a look at the 2nd prototype
Next i will be designing a custom printed circuit board for the interface. This has been a fun project so far. The final product will allow me to use my DX Doubler SO2R controller box with a USB interface, without spending a fortune. This will make it possible to use the great DXD controller with any computer. I may use it with a laptop when I go on my annual VA QSO Party mobile trek in March. Full details of the DXDUSB project will continue to be posted to the SO2R page on this site.
After a weekend-long CW contest at my Home, I jumped into my Ford F-150 to head out, and it was acting very strange. It seemed like the automatic transmission was dead or dying. I knew it was a little touchy going into 2nd gear at times, but it had been working just fine when I parked it for the weekend. I thought my week was ruined and I would have to call for a tow of my truck for an expensive transmission repair.
As I headed out of the driveway, shifting was still awkward. Then I noticed that as it changed gears, the dash display still said I was in 3rd gear. Once I saw that I knew something was fishy. So I went back to the house. I went through a couple power on-off cycles and things started to change. The dash display went nuts briefly, but then it started to come back to normal.
Seeing this change in behavior made me finally realize what had happened. I had parked the truck with its HF rig and screwdriver antenna right under one of my wire antennas, a ZS6BKW. The tip of the truck’s HF whip was directly under the antenna and only about 20 feet away. My guess is that there was RF coupling between the Home antenna and the wiring in the truck. As a result of the RF, some computer memory in the truck got corrupted. Eventually the vehicle must have loaded some historical or factory settings. After that, all was well again.
So now, when I park near the Home HF antennas, I remove the whip from the truck. I plan to do some more RFI mitigation soon, but for now this seems to have solved the problem.
I recently completed testing of the first prototype of the USB interface for DX Doubler using N1MM+ software. This was a rough prototype, so it isn’t pretty but it does seem to work fine. It currently handles RX and TX Focus, and STEREO for listening to both radios at once. There is an FTDI chip-based USB –> Serial converter that allows the interface to fully support PTT and CW keying on the single Serial port that is configured. I just need to add the BAND Data support. The interface uses the Open Two Radio Switching Protocol (OTRSP) that is used by several other SO2R Control boxes. This protocol, created by K1XM who generously shared it with the Ham Community, is supported by N1MM+ and several other Contesting Software Applications.
I used a cut-up LPT cable to connect the DX Doubler box to my interface. The interface uses and Arduino Board. In the photo, the Arduino is still tethered to the PC for power and uploading of Code. But there is no LPT and only the USB interface is now configured in N1MM+. I used an Intronix Logic Analyzer to scan all the data lines before connecting to a rig. Here is a shot of the Logic Analyzer screen.
Remaining work is making a 2nd prototype on a perfboard and testing with both radios.