[RTTY] FW: Icom IC7600 and MMTTY

Dave AA6YQ aa6yq at ambersoft.com
Sun Oct 11 20:09:16 PDT 2009

>>>AA6YQ comments below

-----Original Message-----
From: Gary E. Jones [mailto:garyejones at cmaaccess.com] 
Sent: Sunday, October 11, 2009 8:38 PM
To: 'Dave AA6YQ'
Subject: RE: [RTTY] Icom IC7600 and MMTTY

I do not yet own an ICOM IC-7600 transceiver but am seriously close to making the purchase. Therefore, I am not absolutely positive about this, but the manual indicates right at the start that RTTY in the 7600 is FSK, not AFSK. It is the understanding of a good friend of mine who owns one that the situation is the opposite of what is stated below... that is if you do want to run AFSK that you need to enable the signal out on the back panel and you can feed it to an external AFSK sound card interface. 

>>>Your friend is incorrect. You can transmit RTTY with the IC-7600 in either FSK or AFSK. I have made an RTTY QSO with an IC-7600 using AFSK, with nothing but a USB cable connecting the transceiver to my laptop running MMTTY. I also successfully tested this configuration with WinWarbler, which uses MMTTY as a "RTTY engine".

>>>The IC-7600 includes a Universal Serial Bus (USB) interface that when connected to your PC by a standard A/B USB cable 

 1. emulates a soundcard, allowing an application on your PC to transmit audio to your IC-7600, and receive audio from your IC-7600

 2. conveys CI-V instructions from an application on your PC to your IC-7600 -- including instructions that switch the tranceiver between RX and TX

>>>Using the USB interface to transmit audio to your IC-7600 (AFSK transmission) requires placing your IC-7600 in DATA mode, which is different from RTTY mode; for example, the IC-7600's RTTY-optimized Twin Peak Filter is not available in DATA mode.

>>>If you are using a RTTY application like MMTTY that can issue CI-V instructions for RX-TX switching, and if you are ok with having your IC-7600 in DATA mode rather than RTTY mode, then the USB connection between your PC and IC-7600 is all that's required for RTTY operation.

>>>If you wish to transmit in FSK with MMTTY, you can still use the USB connection deacribed above for receiving audio and for RX-TX switching, but you'll need an additional serial port on your PC with a signal (TxD, RTS, or DTR) that drives an external RS232-to-TTL level converter connected to pin 1 (RTTY) of your IC-7600's ACC-1 connector; this signal switches your IC-7600 between mark and space when transmitting. If you use an USB-to-serial-port adaptor for this serial port, you should use MMTTY's EXTFSK "helper application" so that RTS or DTR can be used, as many USB-to-serial-port adaptors cannot generate the required signal on TxD.

>>>If the RTTY application you're using cannot perform RX-TX switching by issuing the appropriate CI-V commands, then you'll need a serial port signal that drives an RS232-to-TTL level converter connected to pin 3 (SEND) of your IC-7600's ACC-1 connector or ACC-2 connector.


         Dave, AA6YQ

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