Lots of hams are using the Signalink USB interface for a myriad of digital modes on the amateur bands. This site has a lot of information on improving the performance of the Signalink. Down at the end of the page he notes a very simple fix credited to AB8VJ that silences the noisy voltage source by jumping a connection to a regulated supply pin.
Here is a grab of the FFT display of my Signalink USB before the fix. The radio cable is unplugged from the Signalink, so the noise you see from 0 hz tapering down to around 500 hz is generated by the Signalink itself.
After the fix, the same measurement shows dramatic improvement of the low end noise floor. I actually increased the scale a bit on the “after” grab to emphasize the noise, but it was very low.
There is a good picture on the referenced link but I will add a before and after of my own. I used the surface mount resistor and jumper approach, but I would think that using a standard 470 ohm resistor AS the jumper would work as well and be easier. When one of those tiny resistors pops out of your tweezers, forget about it.
Once you open up the Signalink and heat up the soldering pen, prep about an inch and a half piece of insulated small guage wire for the jump. Locate the existing resistor between the Tx and Rx pot and remove it. Solder your new 470 ohm resistor on the inside pad in a vertical orientation. Now solder the jumper, one end to the new resistor top-end, and the other to the edge end of the resistor next to JP4 (that resistor stays put). Done.
While I own several DSTAR radios and enjoy that mode, I am rooting for the adoption of FreeDV as the digital codec of choice on HF. I have written about FreeDV before. It is a truly “free” CODEC that anyone can use without licensing fees. If you have a computer with speakers and a microphone AND a separate sound-chip interface like the Signalink USB, you are set for operation. Just pick up the latest version from http://freedv.org/tiki-index.php for your Windows, Mac, or Linux PC. FreeDV requires TWO sound interfaces. For example, the computer microphone will be digitized by your soundcard and converted back to analog on your Signalink output to the radio. Likewise the incoming radio audio will be converted to digital by the Signalink input and converted back to normal audio by your soundcard/speakers.
All you have to do is set up these pathways in FreeDV and get on the air. Since the mode is pretty new it can be difficult to stumble on to QSO partners. For that, John Hays created a neat online chat utility at http://qso.k7ve.org/ where you can see a live list of FreeDV ops and set up an instant sked. I made my first FreeDV QSO this afternoon with a station in Seattle on 40 meters, followed by a perfect copy from a Florida station on 10 meters.
It is digital but it is voice, so you need to operate in the phone sub-bands, not CW. Give it a try.
Amateur Radio Technician Level Class
Sponsored by Whatcom Emergency Communication Group
Dates: Saturday April 19, 2014 and
Saturday April 26, 2014
The Class will be held at
Nelson Driving School, LLC
2300 James Street Suite 103, Bellingham, WA 98225
We are located one block south of Trader Joes on James Street
Time: 9:00 AM to 4:00 PM both days
Cost: $25.00 for the class and $15.00 for the test.
To sign up or for more information contact:
We only had three candidates take VE exams today but they all passed and everything went perfectly, thanks to Bruce, Don, Scott, Claire, Jim, and Deb. A special thank you to Brian K1BJ who came out to open up the building for us. Two people passed their Tech and one upgraded to General. The new General class licensee credited Bruce Prior’s (N7RR) license course for his perfect score. If you would like to take Bruce’s license course for Technician, General, or Extra, write to him at N7RR@mail.com
The next license exams in Whatcom County will be Saturday February 8 at 1000 am at the Search and Rescue building. Details under the Classes and License tab above.
All Whatcom County emergency communications volunteers are invited to attend a special meeting at the Search and Rescue building near Smith Rd and Northwest avenue (1041 W Smith Rd) on Thursday October 10th at 7pm. Deputy Director of Emergency Management for Whatcom County Kent Catlin will be speaking. This is a regular meeting of the WECG (Whatcom Emergency Communications Group), but all area hams involved in emcomm are encouraged to attend. Kent will be describing his vision for building a communications network within Whatcom County and to surrounding areas.
I finally pulled the pictures that I took at Field Day 2013 in Blaine off my SD card. Here are a few:
Budd WB7FHC drove his electric bug to FD. What a project!
Sarellite ops. They made a QSO just as the bird was falling below the horizon. Alt/Az 440/144 antenna in foreground; operating station under canopy.
Satellite Ops. Don W7AIN making the QSO and tracking Doppler shift on the VFO while Andy WA2TND positions the antenna during the pass. Gary KF7NJU looks on.
Taking a break from radio to rag chew and EAT. Everyone’s favorite FD activities.