I'm no stranger to soundcard RTTY or to my K3, but today I decided to mix the two and fire up MMTTY on the K3. The first thing I noticed is that there was a very strange ticking sound in the monitor. While it was difficult to hear on frequency on another radio, you could hear clicking off-frequency.
Long story short, I guess it was due to overdriving. If I backed the mic gain WAY down, or the soundcard output way down, the clicking went away. (I'm using FP.L - the same connection as I do for soundcard SSB.) Upon further investigation, I need to set the MIC gain to light up only 2 bars on the ALC meter. Anything less and I'm not getting full output power. Anything more and I'm getting the ticking sound (assumed to be overdrive). I can't get nowhere near 5 bars of ALC, and this setting is very touchy...a fine line between full output power and distortion. I've used this same soundcard and homebrew interface for many, many years, on several different radios. It does include isolation transformers and works fine on SSB. I've also listened to the monitor while in TX TEST mode, and the same problem exists, so it's not an RF issue with the station. It's definitely audio related. I've tried FP.L, RP.L, and LINE, all with the same results. For the LINE, I had to crank up the soundcard to max output and MIC all the way up to 40 (of 60) just to get 2 bars of ALC and nearly full output power. Any further and again I hear the ticking/distortion. I got the the latest SW (well, prior to 11/18 it was the newest), 2.63/1.95. Any ideas out there? I'd like to run this thing with a few more ALC bars and have it so it's not so touchy between having distortion and getting full output power. I've seen emails from others saying they are able to run 5 ALC bars. Not sure why I can't. 73 and thanks, Chad WE9V
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