[SignalOne] CX-11 and 1030

[Ulrich Graf]

Hello all,

there was the question before, as where the low pass filter of the
1030C is located since the filter compartment on the top is empty.
These low pass filters are definitely below the receiver module. The
stand-offs in the 1030 to lift the rx compartment are about 8 mm in
length; in the 1030 C the receiver is lifted by about 16 mm to give
enough space for a shielded compartment containing the low pass
filters.

A second question came up about the ALC overshoots of (at least my)
1030 in SSB. This phenomenon has been at least investigated. I fed the
output power via a directional coupler to a dummy and connected a
detector to the coupled power and fed the dc to an oscilloscope. In CW
the output was absolutely constant during the CW signs - either dots
or dashes - and could be nicely regulated with the output power
control. No overshoots could be found! In SSB however there where no
signs of overshoots as well but output power was not constant during
syllables and could easily be increased by simple speaking louder into
the mic. So even with a reduced power (with output power control pot)
to - lets say 100 W - output could reach more than 150 W just by
speaking a little louder into the mic. Now I know why all my
transistor linears switch off in SSB! Why this could happen has not
been found out so far but I will care for this problem.

Two weeks ago I got a CX-11 again on my table. I had this radio before
with the problem that CW sigs were underlayed by a constant carrier
almost as strong as the sigs and lasting as long as determined by VOX
delay. When I had the radio before I could not find a solution due to
lack of detailed manual instructions. This time I had the advantage of
comparing signals and behavior with a reference radio.
CW signal generation is really somewhat complicated and it took quite
a while to understand. Firstly a CW carrier is generated on the
AGC-Board A9 but there within a time period lasting from the first key
down until the end of VOX delay. This carrier is keyed by the diodes
CR16 and CR17. This carrier is fed to the TX mixer board A10.
Secondly the key voltage switches the sidetone and the ALC voltage
from the output directional coupler on ALC board A16. This ALC voltage
now has a double function. It controls the output power AND keys the
transmitter in exact CW rhythm.
Finally these functions are performed in the TX mixer. There the pin
diodes CR4 and CR5 tune the amplitude to the desired level and the
amplifier Q1 before the mixer finally keys the transmit signal.
In my rig the addition of ALC-signals on the ALC board did not work
properly. Now the problem is solved.

Best 73

Uli, DK4SX