[Elecraft] RTTY Operations

[John-Morrow]

> Hey folks, anyone have any ideas as to how to properly set up filters
for RTTY?  Filter settings for KSB2 data are for 1000 Hz tone --- RTTY
uses 2295-2125 Hz tones .... would not appear to fit if FL3 and/or FL4
are tightened to 750 to 500 Hz .  Thanks .... Mike  KG4MTN

I have set my K2 (SN3022) to operate with the
Reg1 tones of 1275/1445 Hz. At 400Hz bandwith
the IF centre frequency was measured at 4913.7kHz.
So I required a BFO range 4912.34-4915.06.
 After a lot of help from Gary and a set of new BFO
crystals I got to the required range by changing
C173 to 680pF and C174 to 330pF.
This is quite a large departure from the 'design'
values but seem to work very well. I have not noticed
 any signs of drift on either cw or rtty.
In recent posts it was mentioned that a 4.7pf
capacitor connected between the junction L33
and BFO crystals ground will give the required
range but I have not yet experimented with that.

I think it may be impossible to set the BFO frequencies
 for Reg1 tones of 2215/2295 Hz.
You could get them set for rtty on some bands,
say 21M and up and for rtty inverted on the lower
bands. But you'd have to remember to change
the settings on the TU when changing bands.

Using 'Spectogram' set markers for the tones
you wish to use and adjust the width/bfo frequencies
so that the markers are centred symetrically within
the passband.
I set FL3 to 700 Hz for general use
and FL4 to 375 Hz for contests. These are 6dB
settings using Spectrogram. My K2 reads these as
 0.77 and  0.66 respectively.

73  es gl
John Morrow GI4KSH