[RTTY] Omni 6/FSK

Keith Regli keith at kregli.com
Thu Mar 4 10:41:11 EST 2004

I use the same scheme as Jim describes followed by a Timewave DSP-599.  The
combination is very good.

You are right, the standard optical isolation circuit will result in an
upside down signal.  You have several options.  I've seen comments that some
folks have gone direct from the serial port to the FSK input on the Omni
with success (they should be in the archives).  Since the Omni manual says
it wants TTL levels and the serial port is RS232 levels I didn't try that.
I prefer using some isolation and adding an extra inverter stage.  Since I
was building a CT17 replacement and an SO2R box at the time the extra
circuitry wasn't a big issue - you can find my approach on my website below.
It's probably more complex than you're looking for, but might give you

Keith Regli (K7KAR)
mailto:keith at kregli.com
-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On
Behalf Of Jim McDonald
Sent: Thursday, March 04, 2004 4:05 AM
To: rtty at contesting.com
Subject: Re: [RTTY] Omni 6/FSK


I had the same radio before I bought an MP.  The best RTTY filters were the
Model 216 9 MHz 500 Hz centered for digital modes cascaded with the Model
282 250 Hz filter for CW.  I think the 282 required the PBT to be rotated to
3-4 o'clock to get the high tones in its bandpass.  The 216 is usable only
on RTTY, which is unlike filters for Yaesu radios, where the RTTY bandpass
is shifted by the radio so that the same filter can be used on CW and RTTY.
(I hope someone will correct me if my understanding is incorrect.)

Inrad may have similar filters.

I liked the simplicity of the radio very much as well as QSK on CW.

Jim N7US

----- Original Message -----
From: "Mike Brown" <k9mi at sbcglobal.net>
To: <rtty at contesting.com>
Sent: Thursday, March 04, 2004 12:40 AM
Subject: [RTTY] Omni 6/FSK

I'm new to RTTY contesting, and I know that I want to make
the switch from AFSK to FSK with my Omni 6 opt 3. I have
the parts to make the interfaces from the AA5AU web site,
but in talking to Don, he thought with the Omni, that may cause
my tones to be inverted. Also, I'd like to know what filters
are preferable to the Omni for RTTY contesting. So, any
help and suggestions from Omni 6 users would be greatly
appreciated. I'm using WriteLog with the MMTTY plugin.


73, Mike K9MI

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