[Elecraft] [K3] yet another K3-to-Titan425-QSK-interface problem

[Jim Brown]

On Wed, 20 May 2009 08:52:23 -0700 (PDT), David Windisch wrote:

>I pulled things apart and set the amp in the triage area, where it has sat
>since.  Have looked into it and the 81219 INPUT BIAS board has some smoked
>components on it.  

One thing that might help you understand Ten Tec's circuit and troubleshoot 
the board is a schematic for all of that control circuitry that's on my 
website.  http://audiosystemsgroup.com/publish

Several failures in the Titan 425 can cause problems in that circuitry, 
including the antenna relays and arcing in the high voltage. The good news 
is that all of the parts are very standard, almost generic, low cost parts, 
and you can troubleshoot them with an ohmmeter. One thing that often smokes 
is a wirewound resistor that's a meter shunt. It's also common for the NPN 
transistors to fry -- they're a bit under-rated for voltage, so anything 
that goes wrong will take out several of them.  

Note also that when things go wrong in the HV, a couple of traces often 
melt in the power supply. There's a note on my schematic telling you where 
to look. 

Repeating my directions for using the K3 with Titan amps. Feed the PTT out 
of the K3 into the PTT input of the Titan, and in the K3 CONFIG menu, set 
TX DEL to 12 msec. This works for SSB, RTTY, CW QSK and CW semi-QSK. 
Shorter delays may work, but that's what I'm using. 

73,

JIm Brown K9YC