[GreenKeys] HRS312 TTY Interface

[Duncan M. Brown]

> [Original Message]
> From: Eugene Hertz <eugene at hertzmail.com>
> To: duncanancy at earthlink.net <duncanancy at earthlink.net>; greenkeys
<greenkeys at mailman.qth.net>
> Date: 10-Mar-09 21:32:10
> Subject: RE: [GreenKeys] HRS312  TTY Interface
>
> Check out Tom Tilson's PC/Loop Interface
>
> http://www.hertzmail.com/rtty/Tilson%20Loop%20Interface/
>

But it doesn't fit inside the 9-pin connector shell!  I had great fun
showing it off to a ham friend who has done real RTTY in the past.  He
couldn't understand how I could connect my computer directly to the 120V,
60ma TTY current loop.  I kept telling him it was a MAGIC cable.  He
finally asked what was inside the connector and I had to tell him.

By the way if you take your output from pins 4 & 6 ("series connection) of
the HRS312, loop polarity will not matter (and you don't have to worry
about how to lable the board correctly).  The parallel connection (that Tom
uses) gives you greater current capacity (which you don't need in a 60 ma
loop) and you have to get it connected to your loop the right way.

  --Duncan