[GreenKeys] Can we do tty 2 meters!>?AFSK ON FM? (was ] Hamtesting)

[Ralph Mowery]

One interisting thig if you do run rtty by feeding the tones into the mic or audio input of a transmitter.

If you want to send fsk by using computer sound cards or other audio generators, set your transmitter to LSB.  This actually puts the tones out inverted and stays with the old standard of the space being actually lower than the mark frequency, but when received on lsb it is reinverted so the space comes out of the speaker higher. Can be confusing.  It does not really mater the actual frequency of the tones as long as they are 170 hz apart.  You usually want them to be atleast 1500 hz so the filters in the transmitter will help eliminate the harmonics of the audio if there is any.
The tuning of the receiver will take care of that.

When using AFSK on AM or FM then you normally will use a mark tone of 2125 and space tone of 2295 which is 170 hz apart.  If using other tones, the tuning of the receiver will not compensate for that.


  ----- Original Message ----- 
  From: Ralph Mowery 
  To: greenkeys at mailman.qth.net 
  Sent: Tuesday, November 19, 2013 10:54 AM
  Subject: Re: [GreenKeys] Can we do tty 2 meters!>?AFSK ON FM? (was ] Hamtesting)


  Yes you can.

  I am not sure about 6 meters, but from 2 meters on up it is fine to do rtty on AM and FM using afsk.  You can also use fsk if you want to.

  A number of years ago a local group used 146.700 as the standard FM rtty frequency.  This was later moved to the 220 mhz band as more and more voice repeaters came on the air.  Not that they had to,but just seemed like the ham thing to do at the time.

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