[RTTY] RTTY crosshair pattern

[Bill Turner]

ORIGINAL MESSAGE: 
On Sun, 03 Feb 2013 13:21:26 -0700, you wrote:

>Backing up can be harzardous. Anyway, I modified my Kam+ several years ago (a 
>Kantronics approved mod) so that I can hook up the scope and get a cross-hair 
>pattern rather than using the LED panel on the front panel for tuning. But, it 
>always displays 2 ellipses on the scope that I can never get to be at a 
>perfect or even near perfect right angles. I don't know if it's possible to 
>get 2 straight lines instead of the ellipses.

REPLY: 
1. When the ellipses are not at right angles, it means the shift of
incoming tones from the receiver are different from the KAM's decoder. The
incoming tones should be 170 Hz apart, but apparently the KAM's tones are
slightly different. Check the manual to see if they can be moved.

2. The ellipses will get more narrow with sharper filters in the KAM, but
it's possible to go too far with this so that tuning becomes critical.
MMTTY has a filter (FIR) which can display lines instead of ellipses, but I
don't think the KAM can. 

3. Unless you are really devoted to the KAM, I would suggest putting it on
the shelf and going with MMTTY. I have run them side by side, as have
others, and MMTTY wins hands down for decoding weak signals. The KAM was
great in its time, but its time has come and gone. 

Bill, W6WRT