[SignalOne] CX-11A cw problem

[Ulrich Graf]

Hello S/1 friends,

After successful repair of a Milspec 1030 - I was even able to detect
and solve a faulty solder joint inside a mechanical sideband filter - I
got completely stuck with a problem of a CX-11A. I mentioned that
before: when switched to transmit all cw transmit signals are perfect
but in VOX mode, all signals are superimposed by a carrier as long as
VOX delay time constant lasts. Or in other words: The cw signal shaping
is not performed correctly. 

I downloaded the shematics from the net and printed them in larger scale
but still can not completely read them (naming of contacts and signals),
especially those schematics of the mother boards. So I'm not able to
track down the switch postions "transmit" and "vox" to see the
differences in activated signals.

What I found so far: the 8 MHz carrier signal is excited in the BFO
module and fed to the AGC board. There it acts as a bfo signal for the
rx path and as CW carrier for tx. Cw signal shaping seems to be done in
the diode switch CR16/CR17 by the T/R signal (?). In "Transmit" mode,
this T/R signal has exact CW shape - therefor cw signals sound
perfectly. In "Vox" mode this T/R signal is lengthend to the time
constant of vox delay - which is corrcet for all other tx functions. But
now only the sidetone has correct cw shape, but rf output is merely a
single carrier as long as vox delay lasts.

Schematic of this diode switch shows a signal "Carrier on/off" (256). I
could not find out if this is an input or output since I'm not able to
find this signal again anywhere in the schematics. Mybe this is the
final cw shaping signal, but where does it come from?

Hopefully there is somebody who is somewhat more familiar with the
schematics of the CX-11 and has deeper insight. Do you eventually have a
hint where to look next?

Vy 73

Uli, DK4SX