ON3JT

Ham radio operators interested digital modes will often use these computer interfaces to automate CW contacts (send morse code from the PC), use the PC soundcard for RTTY and control push-to-talk functions among other things.
Many of the PTT interface drawings  found on the net suffer the same problem. Well it is not really a problem.

Let’s have a look at a typical interface :
You have the RTS and DTR line tied together with diode, then comes a transistor that operates as a switch. And finally the ptt line from you transceiver. So when the RTS or DTR signal goes high, you are on the air. So what is the catch ? Ever booted your computer or used other software besides your regular hamradio soft ? Of course you did and what happened ? My transceiver went in to TX on the wrong antenna / receive converter / mistuned antenna. Luckely the radio was set in SSB and no harm done without modulation. But it could be worse.

So what have I done ?
A simple modification that costs almost nothing : add a simple switch in the PTT line. See the red switch in the interface drawing.

That’s it. When the computer has booted and ready to use, I toggle the switch and can operate the digital modes.

A friend of me asked if I could detect some WSPR signals on 20m. He has been monitoring it a while without any activity.
I also read the comments of G4ILO on the WSPRnet.org site : http://wsprnet.org/drupal/node/384
I must admit that I was also stuck on 30m.
He made a statement and yesterday I had a day off. A whole day of listening later this is what passed my screen :

Timestamp        Call   MHz       SNR Drift Grid   Pwr Reporter RGrid  km    az
2009-01-21 10:48 EA1FAQ 14.097137 -24  0    IN71op 0.5 ON3JT    JO21fe 1274   30
2009-01-21 09:58 VK6BN  14.097091 -23 -1    OF88ac 10  ON3JT    JO21fe 14167 313

Not much.

Hey guys, if you want that propagation monitoring works, we need to activite all bands.

Tonight I used WSPR again to see the activity on 30m. Now I received about 7 stations from the USA, Hungary, Spain, Switzerland, UK and the Czech republic. After a few hours I ticked the 20% T/R option. This switches the transceiver on for 20% of the time and the remaining 80% listening.

And yes, my signal gets out. Using only 2 watts my signal is picked up by VK6KHD, Nigel in Australia. My first.
That is about 14190 km or 7095 km per watt or very very far from my qth

Last saturday night my computer has been running all night long the WSPR (whisper) software from ….. to see if I could receive that mode too. My wife had the night shift in the hospital and could not argue that the computer is making too much noise in the bedroom That is the downside of having the shack in the bedroom.
I set the receiver to 10.138.7 in the 30m band and went to bed.

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After reading this site : http://paginas.terra.com.br/lazer/py4zbz/hamdream/rxdrm.htm I modified my Icom IC725 with a similar capacitor. It worked more or less. Switching to the CW-N mode on my trx and decoding with Dream I could listen to some DRM radiostations. At that time the only antenne I could use was a magnetic loop, mounted near the window. Not the setup that everyone dreams of
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It has been a while that I posted something on my blog here. Don’t panic, I’ll try to do it more frequent.
I’ve been busy with all kind non-ham related things.

But yesterday I managed to find a free moment and put the transceiver on the 20m psk band. Around 20:40 UTC I noticed a qso that needed more attention.
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I made a qso in PSK31 today with SV1EAG, George in Greece. I hear you thinking : “Nothing special…”
But he mentioned this :

(YOU CAN WATCH THIS QSO IN MY LIVE CAM
IN http://www.sv1eag.blogspot.com/ IF YOU
WANT TRY IT)

And I did.  I could see the text that I was sending on his screen via the webcam. I was a bit too late to take a screencapture but if you look close enough, you should see my callsign in the logbook entry of MixW (the grid with yellow background). Very nice thing to have some visible feedback on your signal.

Keep up the good work George and we sure meet again.