[RTTY] FW: OO Advisory kk5oq

[Anderson, Charles, MSG, 255ACS, SCS, 6820]

Chen,
 I received another email from Chazz which states it was not the shift he
was referring to.
Think it was what we called spurs.
Any way thanks for the refresher as we use to run the wide shifts in the
.mil world a long time ago.
There is normally 6 or 7 stations during a contest that I can copy in two or
three places, mainly on 20 meters for some reason and not the other bands.
I have not had any other replies so perhaps at some time during the test I
might have been putting out some spurs.
I run afsk with the mike all the way down and do the adjusting with sc
interface.
The sc vol(windows) is set to minimun also. I normally adjust the output at
50watts with the sc i/f and then back off about 10watts.
Have not worked you in the test for some time now.
73
Charles/kk5oq
 

-----Original Message-----
From: Kok Chen [mailto:chen at mac.com] 
Sent: Thursday, October 20, 2005 10:48 AM
To: Anderson, Charles, MSG, 255ACS, SCS, 6820
Cc: rtty at contesting.com; k7ovg at velocitus.net
Subject: Re: [RTTY] FW: OO Advisory kk5oq

> I thought you may be interested to know your RTTY signal was 450 hz 
> wide vice the 'normal'  170 hz.

A normal RTTY signal has a shift of 170 Hz, but the -30 dB points are
normally about 350 Hz to 450 Hz wide (even wider if you are using an FSK rig
that has keyclicks).

The mystery deepens since it turns out that 450 Hz shift (mark tone is 450
Hz away from space tone) *is* one of the standards used in radioteletype,
just not used by hams.

Hams usually stick to 170 Hz or 850 Hz shifts, the latter at 75 baud.

So, if we assume that your signal *did* change to 450 Hz shift, the next
question is were you using FSK or AFSK?

If you were using AFSK, it is some software in your computer that was
responsible.  But if your were using FSK, then only your rig can be
responsible for the wider shift.

A software modem could not have caused an FSK rig to change shift, since all
the software does is to send the rig an FSK keying signal, although
potentially some rig control software could have made the accidental switch.

73
Chen, W7AY