RTTY on the IC-7600 Using N1MM+ and MMTTY

I have been using the IC-7600 on RTTY with N1MM+ and the MMTTY application for a couple of years now. There are some good directions for this in the N1MM+ documentation, so I am not going to go through all the details. Here is a quick summary, and a screenshot of my setup, including all of the important TABS under MMTTY Setup.

Overview

If you are not using the special ACC connections on the back of the radio, then you will be using AFSK mode. This should work fine, but you need to understand that as far as the Radio is concerned you are NOT using RTTY. Here are some tips on the Radio part of the setup:

1. You want to set the Mode for LSB-D1, which means the first Digital setup under LSB
   1. This is done by pressing the SSB button until you get LSB, then pressing and holding the SSB button, until you see LSB-D1
2. Since the Radio thinks this is an SSB Mode, you can NOT use the RTTY filters
   1. You will instead use normal SSB filters, and can use them as you would under SSB. You will want to set some filters that are much narrower than you use in SSB Mode. I use 800 Hz, 500 Hz, and 300 Hz for my three RTTY-AFSK filters
3. You are going to be using the Soundcard that is internal to the IC-7600 for both Reception and Transmission of RTTY AFSK signals. This will be named “USB Audio CODEC” or something similar in MMTTY.
4. The mark and Space frequencies must be in the SSB audio passband, so you will NOT be using 2125 Hz, but will be using 1775 Hz for Mark, and 170 Hz Shift between Mark and Space tones (for standard 45 Baud RTTY)
5. In the IC-7600 Menu, I set the DATA1 MOD (under the ACC menu) to “USB” but I see now that this does not seem to matter, presumably because the Radio is in SSB mode and is using audio from the Soundcard.

Testing the setup

The best way to test the setup is to get on the Air. Tune some RTTY stations and make sure you see their tones in the MMTTY spectral display. If you do not, then you probably have the wrong Reception Device selected. This seems to get changed, and often needs to be reset when I want to work RTTY. I use the USB Audio Codec device for receiving

Once you are receiving, now you can try Transmit. Set the Power to something like 50 Watts. Don’t forget, RTTY is a 100% duty-cycle Mode (like all Key Down on CW), so you do not want to try to use 100 Watts. Turn on the MONITOR button, so you can hear the audio signal. Bring up N1MM and MMTTY  and try to send something using the Function Keys. When you first start the transmission, you will hear a single tone. Once the keying starts, you will hear the tone switching between Mark and Space. It is very common NOT to hear anything but a continuous signal tone, if things are not setup correctly. If you only hear one Tone, then you probably have the wrong Transmission Device selected in MMTTY. Just like the Reception Device, my Transmission Device gets reset to the wrong device when I am not using RTTY. I almost always have to go in and select the USB Audio Codec, and that fixes it.

MMTTY Setup Screenshots

Here are some screenshots of my Working RTTY configuration for the IC-7600.I will provide shots of most of the TABS in MMTTY. PLease note that I use mostly Default values. There is very little that needs to be setup other than the correct Device selections.

First is a top-level screenshot from N1MM using the MMTTY setup with the IC-7600

Next is the Demodulation TAB. Note the Mark and Shift frequencies. This is what has worked best for me.

Next is the AFC/ATC/PLL TAB. I did not change anything here

Next is the Decode TAB. I did not change anything here. Main thing here is to verify the correct Baud Rate. Standard RTTY uses 45.45 Baud. This is what is nearly universally used in Contests.

Next is the TX TAB. Again, I used all default values here.

The next TAB is the MISC TAB. This is another TAB where I used all default values. Note the TxPORT is set to SOUND. This is probably important.

Finally, the one that matter most – the Soundcard TAB. You must make sure that both devices are set to the Soundcard inside the IC-7600. You will see here that I have changed the name of the Transmission device, but normally the exact same name will be used for both devices. You can change the names, and if you have many Sound devices, I would suggest doing that. You WILL come back to your setup and find that the wrong devices are selected. It is easier to fix the selections if the names re meaningful.

I did this very quickly, to get something up before the start of the NAQP RTTY Contest this weekend. Good Luck and hope to see you on the Air.