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, you might even want a third serial port for that in order to be able  to run it and keep DxLab open. It's easiest 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 program 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 yet 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, approximately 2 feet and the pipe is 15 ft. 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 has proven reliable over a 20 year period. If a fixed height tower is used, the pipe is unnecessary. I put the omega match in the barn simply 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. One 1/2 wave elevated radial is attached at the top of the first section, about 15 feet off the ground. This radial is not grounded and a tap wire runs from the radial 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 on the Top Band. See photos of this setup at QRZ.com.