"Bob Liesenfeld" wrote in message
...
Hey Bob,

I am feeding a signal from my RF signal generator to the circuit on my
workbench. I mention harmonics because the sinewave goes from nice and
clean to "blurry" and looking "smeared" across the screen of my O-scope.
I may *be* overloading it, but I thought that would result in clipping of
the waveform. I have the signal generator set to attenuate the signal
severely, and *thought* that would prevent overloading. Maybe not...

Back to work on it some more, and try to make sure I am not overloading
the device.

Thanks,

Dave

Hi again Dave,
It is also possible that the circuit is oscillating. I have seen amps
are ok with no input signal but will break into oscillation when a certain
freq/amplitude input signal is applied (and vice versa). How did you
build this thing? Circuit board, protoboard, dead bug.....???

Bob


Hey Bob, thanks for your interest.

I built it on a piece of perfboard with point to point wiring, clustering
the active components and their biasing resistors fairly closely. I don't
*think* it is oscillating, although to wouldn't swear to anything just now.

I have the signal attenuated as much as possible, to the point where it
doesn't even cause a wiggle on the scope with my X10 probes and the scope
set to 50mV/div. With the tuner set to resonate, it shows up as about 30 or
35 mV (5 MHz) going into the circuit. The output is 70 or 80 mV, but it is
"blurred" and "smeared" as I described. Also, I just realized that the
scope shows *2* traces, each identicle to the other (only using one channel,
and one scope probe.) I can upload pictures of all this if desired,
probably to alt.binaries.schematics.electronic. Don't know how else to
describe what I am seeing. How could one signal become two traces, each
identicle to the other?

Thanks much,

Dave