Big Dummy's Data Interface

I have long been experimenting with simple soundcard data interfaces for the various data modes but this one seems to beat them all !

The drawbacks of other systems are that:

• A ptt is needed.

• Different programs use different pins on the serial or printer ports or not a printer port or various combinations. This means you need to arrange for the correct PTT control signal each time you change software.

• RF feedback is a big problem with dc coupled systems as well as high voltages when unseen earth loops are present.

These WILL blow up your soundcard/comports and possibly damage your tranceiver. I know because I've done it

• Earth loops often cause noisy signals to be transmitted.

Enter the Big Dummy's Data Interface

It cures ALL of these problems, works like a dream, works on ALL data modes including packet and is really cheap and easy to construct.

The RX bit.

The photograph shows in the top right hand corner an old telephone pick up coil used for recording from a telephone.

It consists of nothing but a coil of wire (like a speaker coil) which picks up the induced field around the speaker.

You stand this on top of your tranceiver's speaker and then plug the other end into the line input of your soundcard. These pick up coils can be purchased from Maplin for about £4. Mine cost me 99p from Maplin but that was nearly 20 years ago.

The TX bit:

You can see from the photograph that there's a short white cable with an RJ45 connector on - for my Icom 706. At the end of this are the in-line "barrel" 5 pin DIN connectors which I use to enable me to quickly interface other pieces of equipment to the IC-706 without the hassle of crimping RJ45's on. Incidently the easiest way to make a patch lead like this without purchasing expensive crimp tools is to buy a CAT5 home networking cable for about £4 and use the cable and already fixed RJ45's to make the patch lead.

And now the really hard bit - find an old transformer.

Mine was pinched from an old 240v to 9v DC adapter or "Wall Wart" and simply used as an isolation transformer.

The output from the soundcard goes to one side of the transformer and the other winding to the rig's microphone input.

Simple eh ?

Now just use the transceivers VOX to operate with your chosen software. If your using packet radio then make sure you don't have a VOX delay that is too long. Usually 0.1 second will be the most you need. On other data modes you may prefer to have a much longer delay - maybe 1 second or so.

It really works.

In fact I've sent this very article to the webmaster using this very interface via packet radio.

Other uses

This data interface can not only be used to work your favourite data modes such as PSK31/RTTY or SSTV and packet radio but for starting up your very own personal beacon.

This is something that I have been playing with over the last few months.

The ethos behind it is that some bands just don't have enough activity on them and I try to send out a personal beacon in the hope that others will hear it and realise the band is open.

This is great for bands like 10m, 6m and 4m in the UK and Europe.

Just use software like MixW (www.mixw.net) and write a simple macro to auto CQ.

With MixW you can right click on a macro and change it to anything you want.

For example here is a macro I use for sending a PSK31 beacon on 50.250Mhz:

<TX><ASAUTOCQ>
G0FTD PERSONAL BEACON
5W INDOOR LOOP
JO01MI
sms +447666 6666 666
EMAIL = jo.bloggs@aol.com
<RX>

or for CW:

<TX><ASAUTOCQ>
vvv vvv vvv DE G0FTD G0FTD G0FTD
vvv vvv vvv DE G0FTD G0FTD G0FTD
<RX>

In fact you can have whatever you want on any mode, rtty, psk31, cw etc.

Simply copy and paste the above into your preferred macro and away you go.
Just make sure you set a time for the auto cq timer, found in
OPTIONS >> AUTO CQ >>> DELAY. I recommend a delay of 3 seconds on CW and 30 seconds on PSK31. Other modes are up to you.

You can also use MixW as a voice key. Why call CQ when the computer can do it for you. Simply record a .wav file with you calling CQ and use this as a macro:

<TX><ASAUTOCQ>
<WAVE:CQ1.WAV>
<RX>

The CQ1.WAV is left in your default c:\mixw directory or whatever.

I have various frequencies that I use my personal beacon on depending upon propagation conditions.

Here are some of my favourites:

10.140MHz CW
28.500 CW
50.080 CW
50.250 SSB

But it's up to YOU to choose.

Just remember NOT to use the "official" beacon bands when your operation may mess up other beacons and that you MUST be in attendance of the beacon when it's running.

Other than that it's all perfectly legal.

Conclusion

So there you have it - an interface perfect for every single data mode or software from Digipan, MixW, AGW packet engine,MMSSTV,MMTTY etc etc.

There's no excuse not to enjoy the data modes.

Good luck.

Andy G0FTD