[RTTY] TS-570 Freq offset

[Wolf (DL6JZ)]

Hello,

let my try a clarification. Frequency offset in FSK and Frequency offste
in AFSK are two absolutely different things from the  radio side.

1. FSK: The radio knws the freq offset because tx carrier freq and the
BFO freq do have this offset in the RTTY position of the mode switch. So
the frequency offset can be calculated by the built in frequency
counter. And this offset correction works ONLY in the RTTY position.

2. AFSK: The mode switch is in LSB or USB. The frequency of the
(suppressed) tx carrier ist the same as the BFO frequency. There is no
offset! And the radio frequency counter is not able to calculate it. The
only way would be an additional menue item for entering a user defined
value of a freq offset in the LSB/USB position. May be the radios will
have such a menue item some day because there are enough user requests
for it. But in this case you have to pay attention very much when you
change from AFSK-RTTY to SSB operation vice versa!!! To eliminate this
problem .... A way without any end.

73 + 55
Wolf, DL6JZ


-----Original Message-----
Date: Wed, 11 Jan 2006 18:40:52 +0100
Subject: Re: [RTTY] TS-570 Freq offset
From: "Dick Kriss, AA5VU" 
To: rtty-contesting 

Wolf,

You are correct.  I thought you were talking about AFSK.  When Kenwood
designed the TS-570, they assumed all RTTY would be run in FSK and
operation
in AFSK for RTTY was not even a consideration.  The rig was designed
before
sound card technology became popular.  When the TS-570 is in FSK mode,
the
mark frequency is the displayed frequency.  For those of us that can
only
transmit in AFSK, we operate RTTY in LSB and have to subtract 2125 Hz
(if
using that tone) from the dial frequency to determine the mark
frequency.

An  easy example is copying the W1AW RTTY bulletins that are broadcast
in
AFSK to come out on the mark frequency of 14.095.00.  The TS-570 copies
W1AW
at 14095.00 in FSK mode but if I put the rig in LSB for AFSK I have to
tune
the dial display to 14097.125 or 14.095 MHz + 2125 Hz.

Since most RTTY operators 'tune-to-print' most of the time the offset is
only really important when spotting a station on the cluster or knowing
where to set your display to find a spot on the cluster.

Yes, I know modern (more expensive) rigs do the mark offset for you and
some
software and logging programs also handle the offset.

73, Dick AA5VU


> Subject:  Re: [RTTY] TS-570 Freq Offset
> From:  "Wolf (DL6JZ)" 
> Date:  Wed, 11 Jan 2006 12:34:52 +0100
> List-post:  
>
> Sorry Dick,
>
> my posting was not exact enough. The radio is able to correct the mark
> frequency offset only if you operate FSK (mode selector = RTTY)!!
>
> 73 + 55
> Wolf, DL6JZ


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