[Elecraft] K3 - MicroKeyer 2 - mmtty transmit issues on RTTY using FSK-D mode

[Kok Chen]

On Oct 24, 2010, at 4:57 PM, Jim Spears wrote:

> I hear a single tone in the monitor and the P3 also shows the same thing.  

A microKeyer does not modulate the FSK keying signal unless the keyer is commanded to do so by the software that is controlling it.  If nothing is sent to the keyer from the controlling software, the keying pin from the microKeyer to the K3 will be in a constant Mark state (a single fixed carrier).

A standard convention in Amateur RTTY is to insert the Baudot <LTRS> character when nothing is typed.  This produces the familiar two tone "diddle" signal that you hear from RTTY stations when they are idling.   Among other things, the diddle provides a reference for the automatic threshold control function in the demodulator to work on in case selective fading causes the two tones to have unequal energy. 

However, the microKeyer by itself does not automatically insert these characters for you.  The software that is driving the microKeyer is the one that is responsible for inserting the Baudot <LTRS> characters when the "input buffer" is empty (i.e., when you are not typing).

If the software is doing the proper thing, you should see the green front panel LED on the microKeyer II flashing.  If the FSK LED on the microKeyer II is fixed in the on or off state, you might check if there is a "diddle" option in the software that needs to be turned on.

73
Chen, W7AY