[RTTY] Calling Stations OFF Frequency

[Dick Kriss]

> You guys just answered a question I have had -- how do some guys, not too
> many but one or two, answer my CQ's W-A-Y off frequency..

I am an AFSK operator and have noticed the same thing when calling CQ.  When it happens, I usually suspect the calling station failed to zero his RIT from the last QSO; or if he is an AFSK user has found and decoded my CQ off his rig's sweet spot on the spectral display. Many AFSK operators assume is their transmit frequency is locked or slaved to where they place the mouse on the spectral display. This is not always true. It depends on the software used.

If you are an AFSK operator, try this. Turn ON your rig's transmit monitor.  Mouse select at one end of the spectral display and transmit.  Note the tone of your transmitted signal. Now mouse select at the other end of the spectral display, transmit and notice the tone of your signal. It will be different. W1HKJ has a neat feature in fldigi called the QSY button. If you have mouse selected a station on the spectral display that you want to call, click the QSY button and fldigi moves the signal and the VFO to your assigned sweet spot on the spectral display. In addition to bringing the signal to your optimum decoding spot for the rig's filters, it syncs your transmit. When you have the Rx and Tx on or close to your rig's sweet spot the transmitted AFSK signal sounds just like an FSK RTTY signal.

When operating in S&P mode, I narrow the Kenwood TS-590's IF Filter so only a small slice of the spectral display is active around my assigned sweet spot - I use 1000 Hz for the sweet spot. I then tune the band using the VFO to bring the CQ signals into my defined pass band.  I am old school and still like to tune the band using the rig's VFO and use the mouse and software features for touch up.

I do not want to get into a Pro/Con discussion of AFSK vs. FSK but the above may be one explanation of why some stations may transmitting a little off frequency. 

73 Dick AA5VU