A simple soundcard interface for digital modes By J.B.Randall, W1ZE

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1 A simple soundcard interface for digital modes By J.B.Randall, W1ZE If you are new to the HF bands or a seasoned veteran thinking of trying your hand at TTY, PSK, MFSK and the other digital modes you may already know you need a way to connect your PC or laptop to your HF transceiver. The device needed is called a soundcard interface and there are a lot on them in the Ham Radio marketplace with names like Signa-Link, MFJ, Little Rascal, West Mountain, etc. They are all good and will do the job. Some have a lot of bells and whistles but they all do the same thing. As you may know I am a DIY person and like to build things. Over the past dozen years I have assembled several types on soundcard interface devices, from very simple to complex. All worked as designed and help me enjoy the digital modes. In fact I think I have put article into past Squelch Tales newsletters describing several types I have built and used. These days, I appreciate building things using the KISS (Keep It Simple Stupid) design method. Since I own several YAESU and ICOM transceivers I wanted a simple interface that would work with both makes and most models without disrupting the rigs microphone and speaker circuits. So I went to the Internet and started to see what others had built. Most of the designs used rig keying functions from data provided by the computers serial output connection. Problem one, my PC and laptop(s) no longer provide a serial port, only USB and printer outputs. Technology marches on, I guess. If you have one of these computers and want to use an interface device that needs serial port data to do your PTT keying, you need to buy a serial to USB interface adaptor. I didn t want to spend the money for one, so back to the Internet I went looking for more ideas. 1

2 What I came up with was a tone keying circuit that used the data (audio) voltage from the computers audio output (or line out) to drive a keying circuit. Using that found information I bread-boarded a audio rectifier circuit using two 1N914 switching diodes to produce a small DC voltage to drive a single NPN transistor (like a 2N2222) and it in turn would take the transceivers + key-line voltage to ground keying the transceiver. The little circuit worked well. Now to build a hard copy. With two very small 600/600-ohm audio isolation transformers, salvaged from a few junk PC soundcard boards I started to assemble the small circuit board. I highly recommend using the transformers to isolate the electrical system in the PC from the electrical and audio circuits in the transceiver to keep hum and hash out of your transmitted signal. As you can see in the above diagram, audio signal is sampled from the secondary of the isolation transformer on the incoming PC audio/data line through a resistor and coupling capacitor feeding the rectifying diodes. After some experimenting I found out that a 1 uf electrolytic capacitor at the base input of the 2N2222 giving me about a second and a half keying hang-time, good for PSK and RTTY. If you want more hang time increase the capacitor value to 10 to 22uF. For less hang time try a.47 uf cap. I housed the entire circuit board into a 1x2x5 inch black plastic project box. This circuit will work with most all HF transceivers. My ICOM & Yaesu rigs have a rear apron 6-pin mini- DIN data jack that can be used for digital modes. Fortunately the pin-out on the DIN jack was the same for both manufacturers. Data-in, Data-out, PTT and ground pin-out connections are the same configuration.. I salvaged a 6-pin Mini Din plug & cable off an old busted computer keyboard and wired it to the interface circuit. I can plug the interface into the ICOM or Yaesu transceivers and it functions well and no need to unplug the transceivers microphone or external speaker to do digital modes. As a final note: Some Yaesu rigs like the FT-450D, FT- 897D, FT-857D and others with the rear apron Mini-DIN data ports, also have a programmable Digital VOX command setting that when the rig sees audio/data on the data input circuit the Digital VOX keys up the rig, thus eliminating the need for an external audio/data keying circuit. All that is needed for these rigs is an interface assembly consisting of two small Isolation transformers a few resistors, a capacitor and a 1K linear taper mic/data-line level pot. 73 W1ZE 2

3 The Cordermans,W3ZD/W2ZD & K2CML Members of the MARA Roy s Corderman, W3ZD s two sons followed in their father s footsteps by becoming ham radio operators. During WWII Roy helped develop radio and recording devices for the War Department. Oldest brother Sidney Sid K2CML became one of the founding engineers for McIntosh Corp, the Audio recording, HiFi and Stereo developers. Sid now in his early 90s and until last year lived in Five Islands, Georgetown, Maine during the summer and wintered in Scottsdale, Arizona, where he now resides full time. The Youngest son Allan Al now holds his father s call of W3ZD. Al is a Naval Academy Graduate and Navy Pilot. He went on to earn a MBA from Harvard Business School. Al was also with RCA Communications in Palo Alto, California. Later in life he and his wife started a publishing company here in Maine. Al now lives at the Highlands in Topsham but still attends MARA meetings and activities when he can. Both Sid and Al are long time members of the MARA. Above is a photo of Roy Corderman, the original W3ZD standing next to a prototype VHF transmitter with the brass tube wave-meter. The meter is now in the possession of Bob Oxton, W1RSO. Roy was a mover and shaker in the early days of Ham Radio and radio communications. During WWII Roy worked in the Washington Physics lab working on electronic equipment to help in the war effort. He was given special recognition by President FDR shown in the following photo. 3

4 Roy W3ZD at his station in Roy with son Sidney having Field Day Al operating a solar power station the early 30s in the 30s during Field Day 2009 in Topsham A FAMILY OF ACCOMPLISHED HAMS. 4

5 Field Day 2016, a ho-hum event due to a blank sun Again this year the MARA s KS1R Field Day team set up operations at the Topsham Red Cross facility during Field Day weekend. Weather was good but the HF bands to say the least were not accomidating. The folks who attended had fun and some QSOs were made with several folks got their first chance to try out PSK and RTTY. Rich, AB1YX & Norm, W1MKD doing PSK & RTTY The major reason for the low QSO total was that Old Sol had no spots, just a blank sun. Tad Cook, K7RA who does the propagation forecasts for the ARRL wrote: There were no sunspots during all of Field Day weekend. The last time we saw a blank Sun (before June 2016) was Just one day, on July 17, Sunspot number was 0, and only for one day. Prior to that, there were just two days in 2011, on January 27,and on August 14. Prior to that there were 51 days with a blank Sun in 2010, with 12 periods ranging from 1 to 13 days. The longest periods were 11 days beginning on May 9, 2010 and 13 days beginning on April 1, These recent periods of no sunspot activity are a surprise to me, even though we are in a declining half of the solar cycle. Jim McIrvin, N1IPA setting up the Sat-Comm antenna in hopes of a contact 5

6 Here is our submitted report to the ARRL: Call Used: KS1R GOTA Station Call: none ARRL/RAC Section: ME Class: 1F Participants: 26 Club/Group Name: Merrymeeting Amateur Radio Association (MARA) Power Source(s): Commercial, Battery, Solar Power Multiplier: 2X ARRL s New England Divison Director Tom Frenay, K1KI stopped by to show League interest in the MARA s Field Day effort Bonus Points: 100% Emergency power 100 Media Publicity 100 Public Location 100 Public Information Table 100 Formal message to ARRL SM/SEC 100 W1AW Field Day Message 100 Formal messages handled - No.= Natural power QSOs completed 100 Site Visit by invited elected official 100 Site Visit by invited served agency official 100 Submitted via the Web 50 Educational activity 100 Total Bonus Points 1,150 Score Summary: CW Digital Phone Total Total QSOs Total Points Claimed Score = 196 Submitted by: Donald Wakeman, KA1WAL Comments: (blank) Rich, AB1YX holds a training session on the Raspberry-Pi and its usefulness in Ham Radio Band/Mode QSO Breakdown: CW Digital Phone QSOs Pwr(W) QSOs Pwr(W) QSOs Pwr(W) 160m 80m 40m m m 10m 6m 2m 1.25 Other Satellite GOTA TOTAL As you can see by the above QSO tally the bands did not cooperate for our 1F effort. But all in all, 6

7 those that came out to the KS1R Field Day had fun and maybe learned something too. its feed from the worldwide DX spotting Telnet system. The graphics are good and easy to read. It is also interactive and you can post spots and set your own spotting filters. It is not as fast as the direct Telnet system which has instant input postings. DXWATCH updates new postings about every 60 seconds but I can live with that, plus I don t have to use a dumb terminal program to access it. Another thing it does do, when you put your curser on the spotted call sign the DX stations data appears on the screen like country, zone, etc. a nice added feature. Try it, you may like it, and it is FREE. DXWATCH a useful tool in the shack By W1ZE Chasing DX, looking for that new grid on six meters or a VHF/UHF weak signal station is a lot of fun and every little advantage helps land a good contact. To this end I rely heavily on the Internet based DX spotting services. The one I use the most is a direct connection to one of the various Telnet DX spotting nodes. Check out for more info on the Telnet system. With Telnet you have to make your PC or laptop emulate a dumb terminal using a free program such as PuTTY. The spotting service works well and is fast and interactive. The other day the Telnet spotting system went down for hours while I was looking for six meter spots out of Europe. Bummer Dude! I quick went on a Google search for DX spotting sites and came across a free access site called DXWATCH at so I logged onto the site and set up an account. It appeared to have the same spotting listings as the Telnet system and I think maybe it is getting JULY 2016, A GOOD MONTH FOR SIX METERS The first part of July found some increased sporadic-e and enhanced F layer DX activity on the old six meter band. Even those of us up here in Maine were experiencing some good band openings across the pond into Europe, North Africa with an occasional signal out of the near east (i.e., Israel & Jorden). In addition there was some double hop propagation to the west with stations from the Pacific northwest making it out to the northeast. Mid month evening openings would last into the late hours with midwest and Rocky Mountain region stations pounding into Maine and Atlantic Canada. The evening of the July 13 th had wall to wall signals throughout the SSB portion of the band and a lot of CW activity between and MHz. Stations with high power and big beams as would be expected were easy to work but even stations running 100 watts or less into dipoles and halos could be worked with ease. If you have not tried your hand at six meter SSB and/or CW, string up a dipole (9 ¼ feet long) and give the band a try. You may enjoy it. 7

8 BOXBORO By Bob DeMattia, K1IW Boxboro! is less than two months away, so our event planning is in full swing. We are close to publishing our forum schedule - look for another announcement in a few weeks. In the meantime, take a look at our Friday and Saturday evening programs. At our Friday DXCC/Contesting dinner, David Collingham, K3LP, will brief us on the recently completed VP8S DXepdition. On Saturday, noted radio historian Donna Halper will treat us to "Heroes of Amateur Radio: Past, Present, and Future". Visit our website for more info. While you are there, you can sign up a friend for a license class or VE Exam. You can also reserve yourself an operating slot at our W1A special event station. ARE YOU UP TO DATE? If you can not remember the last time you plunked down $10 for your MARA yearly membership, most likely you need to get in touch with Marjorie Turner, KX1I kxxx1i@gmail.com and bring your membership up to date. If you are not a member and would like to become a member of the Merrymeeting Amateur Radio Association (MARA) you can get all the membership information needed from the Association s website at We would love to have you join us. Rockwell Collins to End Mechanical Filter Production We still have opportunities for those that would like to volunteer a few hours of them time at the convention. Volunteers will receive a voucher for a free lunch. Finally, we've published a "Guide to Quick Entry" on our website to learn how to avoid those entry lines. Visit our website today to find more and purchase tickets! 73, Bob DeMattia Chairman, Boxboro Convention 2016 Committee P.S. Even if you've already ordered tickets, please be sure to check our website for program updates. As more and more communications equipment designs have adopted digital signal processing techniques, Rockwell Collins has announced that it will stop manufacturing its renowned mechanical filters. It did not provide a specific date. Over the past several years, we have seen a dramatic reduction in demand for narrowband analog filters, the company said on its website. Due to this and other economic reasons, [Rockwell Collins] Filter Products will be 8

9 discontinuing its mechanical filter products in the near future. Rockwell Collins makes two different types of mechanical filters, many of which have found their way into Amateur Radio products and applications. In a mechanical filter, input and output transducers convert the electrical signal to and from resonant mechanical vibrations, respectively. For frequencies between 100 khz and 700 khz, we create filters made from rods resonating in a torsion mode, the company explained on its website. For frequencies below 100 khz, we use flexure code bar resonators. Collins has made mechanical filters for more han 6 decades, and their initial application was in telephone circuits. The filters gained favor for Amateur Radio use because of their excellent selectivity, especially in IF applications. It is said to take about 12 weeks to manufacture a single unit. Art Collins, W0CXX (SK), founded Collins Radio Company in 1933 in Cedar Rapids, Iowa. That same year Collins supplied the equipment to establish communication with the Byrd South Pole expedition. Over the years, Collins produced a line of Amateur Radio equipment, and its products remain popular among radio amateurs and collectors. Rockwell International purchased the company in 1973, and Rockwell Collins was spun off in Today, the company has focused its market on electronic communications, avionics, and in-flight entertainment systems. Thanks to Mike Morris, WA6ILQ; Rockwell Collins 9