[RTTY] ICOM IC751 on RTTY

[Joe Subich, W4TV]

Bill, 

The appropriate ways to use RTTY are shown on page 20 of the 
IC-751A manual.  In essence, the 24 pin Accessory plug can be 
"mapped" to the present 8-pin ACC(1) as follows: 

     8 pin   IC-751A 
       3        3       PTT 
       5        4       RX Audio 
       4        5       TX Audio
       2        8       Ground
       1        9       FSK  (Mark=Open, Space=Closed) 

One item to consider - the Mark/Space sense of the IC-751A 
is opposite that supplied by most simple interface circuits. 
You will need to set S2 on the "Main" unit to "Reverse" for 
normal operation (See: section 13-4 of the IC-751A Manual). 

One may use the IC-751A RTTY mode for FSK or the LSB mode 
for AFSK with generally available software and interfaces. 
Since the IC-751A VOX is active in LSB, one could connect 
soundcard Line Out and Line In to the TX Audio and RX Audio 
connections on the Accessory jack, set levels and use VOX 
for PTT at least to start 

The appropriate Molex Plug and pins are available from 
supply houses such as Newark, Mouser, and DigiKey. 

73, 

   ... Joe, W4TV 
               



> -----Original Message-----
> From: rtty-bounces at contesting.com 
> [mailto:rtty-bounces at contesting.com] On Behalf Of Bill Axelrod
> Sent: Monday, August 17, 2009 3:56 PM
> To: RTTY at contesting.com
> Subject: [RTTY] ICOM IC751 on RTTY
> 
> 
> A friend has an older ICOM IC751 and is interested in getting 
> into RTTY. Anyone out there use an IC751?  Any ideas on the 
> best way to use that rig with a computer/sound card based RTTY setup?
> 
> Thanks and 73...   Bill ND9E
> 
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