Signalink USB Review

Signalink USB Package

The Signalink USB is an interface that allows a computer to send and receive audio to a transceiver.  With it you can operate the myriad “digital modes” on the ham bands like PSK-31, WINMOR, Slow-Scan TV, Olivia, FeldHell, MFSK, Throb, Thor, etc, etc.  All the device does is pass audio to and from the radio.  It is the software that defines the communications.  AGWPE will let you run packet on VHF without a TNC, including Winlink email access.  EasyPAL will have you sending digital photos on HF at 3000 bits/second.  Echolink will let you create a node with your base radio and Internet PC so you can work the world with your handie-talkie in the back yard.  The NBEMS suite of FLDIGI/FLARQ will enable several different modes and allow error free message handling for emergency communications.

I recently purchased two Signalink USB computer/radio interfaces from Tigertronics in Grants Pass, OR.  The units are sold direct from the manufacturer for $99.95 plus shipping.  I just received a new catalog from HRO that indicates that they are now selling the units as well.  The price includes one radio cable selected at the time of order.  A couple of the cables with 13 pin DIN plugs add $5 to the cost.  Additional cables are available separately for $8 – $25 each, depending on configuration.

My units arrived by UPS ground, well packed in a cardboard carton and foam “peanuts”.  Included in the package are the unit, a USB computer-device cable, a radio-device cable, a mono 1/8 in. audio cable, 6 jumper wires, hex wrench, mini CD of software, and a 12 page instruction guide.  I already own two of the original Signalink SL-1 units which are similar to the USB model except that they do not have an internal sound card- they depend on audio lines from and to a computer soundcard.

The Signalink USB is bar-none the easiest computer/radio interface I have ever set up.  I use a Microkeyer interface from Microhams on my HF base station, and while it is very powerful and customizable, it takes hours to configure and is extremely complex.  First you will need to open the aluminum Signalink case by removing the four hex screws on the front plastic panel.  Pull out the panel with the circuit board.  One of my two units had a very tight fit and I had to push the board from the back with the eraser end of a pencil through the RJ-45 hole.

Circuit board with jumpers

Next you will need to place the jumpers in the header on the circuit board per the directions for your radio model.  There might be a jumper diagram in the package containing the included radio cable, but if there is not, or if you misplace it, the information is on the Tigertronics site. I got both of my units with the popular 6-pin mini-DIN “data port” configuration which works on all of my VHF/UHF radios (Kenwood, Yaesu and iCOM), and luckily my Yaesu-857 HF rig as well.  At this point I will mention my only criticism of the Signalink devices (both USB or basic SL1+).  The Signalink is customized to your radio by BOTH the cable AND the jumper settings inside the case.  If you want to use the device on two different radios that have different jumper settings, you will have to open the case and change the jumpers.  Tigertronics does sell plug-in headers for $5 that can be hard-wired, making it much easier to change settings, but you still have to open the case.  I wanted to occasionally use my Signalink with my Kenwood HT.  Rather than change the headers, I simply custom wired my own cable to work with the current jumper layout, thereby allowing me to use the device with either radio by just changing the cable.  By the way, the radio jack is a standard 8 pin RJ-45 with the wiring and color coding of standard Ethernet cables, so “networking types” will be able to whip up custom cables pretty easily.

Rear panel view

Once the header jumpers are in place, close up the box and replace the 4 hex screws.  Plug your cable in to the radio and the Signalink.  Depending on the wiring instructions, you might have to run a (included) cable from the radio speaker jack to the Signalink.  The 6-pin data plug has all of the needed signals so you will not have to take this step if you use it.  There are jacks on the back of the Signalink for these and other optional connections which are explained in the instructions.  If you have been using computers for a while you know that you should never plug in a new USB device until you have installed the drivers.  Surprise! The Signalink USB uses a standard driver that is already built in to Windows XP/Vista/7, so you can just plug it in and go.  Windows will install the driver and a new sound device called “USB Audio Codec”.  At this point you want to go to the control panel in windows to the audio devices and set the default sound card for playback and recording back to the one built in to your PC.  In my experience, when Windows sees the new Signalink it becomes very excited by the presence of a new device and sets IT as the default sound card.  We do not want “You’ve got Mail!” going out over the air.

That is basically it.  You are ready to operate.  Got to and download and install the FLDIGI program for your computer and install it.  Go in to the CONFIGURE / SOUNDCARD menu and select the USB audio CODEC as the input and output, then save the settings.  Set up a sked on VHF or tune some stations on HF to read the mail.  One thing you will probably have to do is boost the volume setting IN SOFTWARE in the computer.  Double-click your speaker icon in the system tray (bottom right).  Select OPTIONS / PROPERTIES. In the MIXER DEVICE dropdown, click USB Audio CODEC.  Make sure the PLAYBACK button is black, then click OK.  Now make sure that the volume is at 100% on WAVE and speaker is above 50%.  I had to set both at 100% on my Netbook.  If you are sending and your PTT is not lighting up, it is almost certainly the result of this level setting not being set high enough.  All of this is covered on the Signalink web site in their FAQ.

Front panel view

The strength of the Signalink USB is its simplicity.  There are usually just two cables needed: one to the radio and one to the computer.  The device draws its power from the USB port.  The front panel has the following controls: A power button with a green LED which activates the PTT relay circuit.  Any time the USB cable is plugged in, the unit is “on”, but if the power is “off”, the radio will not transmit.  Next is a red LED that lights during PTT/VOX activation.  The three knobs adjust the TX (Transmitted audio level), RX (Received audio level) and DLY (VOX delay).  In my experience on a couple of different computers, you should start out with the TX at about 9 o’clock, the RX at 12 and the delay fully counter-clockwise.  Some modes like FeldHell and CW will perform better with a longer delay so you will need to adjust as you change modes.  Be careful how high you run the TX setting, as excessive drive will make your signal wide and distorted.

VOX is shorthand for “voice operated transmit”.  In the case of the Signalink, there is a circuit in the unit that “pushes the push-to-talk button” any time an audio signal is detected at the output of the sound card chip.  Many interfaces and software programs are designed to use a hardware PTT (push to talk) circuit via a serial or parallel port.  Since the Signalink is generating the PTT signal when a sound is sent, you can ignore those port settings in the programs you use.  If you can’t set them “off”, you might be able to set them to a non-existent port number.  One note of caution- Since any audio out to the Signalink will key the transmitter, remember that the power button will shut OFF the transmit PTT signal if you have a malfunction.

While I have only been using the Signalink USB for about a week (to excellent effect), it has been the device of choice for the WINMOR developments team.  WINMOR is a demanding communications package currently in beta testing that requires a very stable computer sound card.  While most computers have a built in sound card, using them on your radio gear can be problematic.  To do so, you will have to disable all operating system and other sounds so the beeps and boops do not go over the air.  Setting the levels will also be difficult if you change from listening to music on speakers, to using the radio interface.  An interface to the radio is really a necessity too.  While it is possible to run a cable from your speaker jack to your radio mic jack, and from the radio speaker jack to your computer line-in jack, you will likely suffer from RF hum and ground-loop noise effects.  Radio interfaces like the Signalink provide DC isolation of the radio and computer with transformers on the audio i/o and a relay on the PTT line.

There is a WORLD of communications modes to learn about for anyone with a computer.  I don’t know of a better combination of low cost and ease of use to get involved than the Signalink USB.  I highly recommend the free NBEMS software package aka FLDIGI as previously mentioned as a starting point.  If you are new to digital communications, see the beginner’s guide. The authors of FLDIGI also have a nice internet reference to many of the soundcard modes with waterfall screen-captures and sample audio files to help you identify many of the signals you will hear.  If you live in the neighborhood, come to a meeting of the Mount Baker Amateur Radio Club – Digital Group at the library in Ferndale Washington (2222 Main St) at 7 pm on the THIRD TUESDAY of every month except July & August.

2 thoughts on “Signalink USB Review

  1. Good Evening, my name is Sergio and i write from Italy.
    I have a Tigertronics Signalink USB connected to a FT 857/DI.
    I tried to use it with Echolink but when i push the PTT on the radio the interface doesn’t transmit… What do i wrong?
    If i rightly understood i should be able to be in a frequency (so when i push the ptt some radioamateurs can hear me locally while the voice is transmitted via the internet) and when the friend i am calling will answer i will be able to hear from him on the radio, even if he is transmitting on another frequency…
    I hope you can help me to better understand.
    Thanks a lot.

    • Hello Sergio. When using the Signalink with Echolink you must use the COMPUTER to send and receive audio. If you speak into the radio microphone, the audio will go out the radio but can not go back to the signalink or computer (the radio speaker is muted). You will need to plug a microphone into the computer and use the Echolink program to make PTT (usually it is the spacebar).

      Cheers! -Brian


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