starman wrote:

I have the schematic sets for both the early and later SW8. The early
models were reported to have a poor impedance match for the whip
antenna. The later schematics show some changes in the componants of
the double diode circuit which protects for static electricity on the
whip. This circuit is also connected differently to the following
circuits in the later model.

There's a change in value for the series resistor on the gate of Q1
(2SK152), the whip amp'. Some of the capacitor values in this gate
circuit are also changed. Q1 might be running at a higher gain in the
later models but this would only affect the whip sensitivity because
the other HF antenna inputs bypass Q1 through the antenna selection
switch (SW2) on the back of the receiver. I think these changes
(above) were made in 1994. The biggest change occurred in 1996 when
the selectable sideband sync' detector was added. The first digit in
the serial number denotes the year of manufacture.

How did you inject the test signal? Maybe your SW8 is out of
alignment.


I had the early (1994) model and while it was fairly deaf on the whip, it
was very sensitive on my external random wire. Not quite as sensitive as my
R-5000 but not far behind. One of, if not the best audio receiver(s) I have
owned.
Brian Denley
http://home.comcast.net/~b.denley/index.html