Interfacing laptop with WSJT

WSJT 65 (and variants) Discussion
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Interfacing laptop with WSJT

Post by VK1PWE » Thu Jun 17, 2010 10:29 pm

Hi all,

I'd like to use WSJT on a Dell laptop with RS232 and USB connectivity. Software all loaded up and ready to go, except for connectivity to the radio (Icom 910). Can anyone suggest a suitable cable to use? Probably don't have time to build anything too complicated, so am leaning toward a ready made cable.

Grateful for any suggestions.

73s, Scott

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Re: Interfacing laptop with WSJT

Post by VK2GOM » Thu Jun 17, 2010 11:14 pm

Hi Scott,

You are probably best using a dedicated data modes interface, with 'Vox' keying and isolation transformers in order to avoid annoying ground loops and all sorts of other pesky audio related issues. It's not generally as simple as feeding audio out to in, and in to out with cables.

Have a look at the Tigertronics range - they are well made and work well. You can buy the interface, and a connecting cable to suit your particular radio at the same time.

73 - Rob VK2GOM / G0MOH

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Re: Interfacing laptop with WSJT

Post by VK3KH » Fri Jun 18, 2010 8:40 am

Rob is right with his advice that you need Soundcard interface to run any of the WSJT suite. As you are using a laptop, it has become common to use USB connectivity.
I have been using the Tigertronics Signalink USB for about 18 months now with an Icom IC7400 and it has proven very reliable. It takes a minimum of set up, and you will be on air in no time.
Can I recommend if you order one, choose the data port connection cable (6 pin). This has a number of advantages including:
a. does not tie up the microphone input
b. the volume control does not effect the data port
c. it can use the same cable to connect to Yaesu radios such as the FT817 (great for transverters).

It was the interface of choice for the VK9NA DXpedition in January this year.
Check out

Michael VK3KH

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Re: Interfacing laptop with WSJT

Post by VK3PF » Fri Jun 18, 2010 10:34 pm


The answer depends upon if you are willing to have a go yourself, or just want to spend $$ and buy a commercial "solution", which may still require adjustment (fiddling!).

There are lots of designs out there for interfacing.

You say the Dell has RS232 - that makes one step easy - PTT control.

Basically the interface needs:
Isolated Rx audio and separate isolated Tx audio connections: basically an isolation transformer in each of Tx and Rx audio lines between PC and transceiver. It is usual to include level adjustment in one or both lines.
A control line for PTT, which averts potential issues with using VOX activation. The usual technique is to use the RS232 control lines to activate the input of an optoisolater chip to switch the PTT line on the transceiver. The optoisolator may need to be a Darlington type, depending on the radio.

There have been designs published in Amateur Radio and elsewhere in the past that show what is needed.

MNCARC is offering a kit at present - $50 plus postage. Easy to assemble.

I have built several interfaces, using either breadboard or my own pcb design - it is not hard.

Another option is the system described by David VK3HZ at last year's GippsTech - all based on USB interface and built in audio interface, leaving the laptop audio separate. Cost about $40.

Good luck,

Peter VK3PF

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