Allison,
Here are my AC and DC measurements for the Q3 amplifier circuit. I
had used a scope to measure rather than my voltmeter, so measurements
are eyeballed.
With R set to 12V from an external power supply.
Anode of diode is 9 V
Cathode of diode/collector of Q3 = 8 V
Base = 3 V
Emitter = 3 V (probably a tad less due to BE voltage drop)
From BFO through an attenuator, I am applying 10.7 Mhz signal of
5mV pp seen by scope injected at junction of input capacitors
25 mV pp same frequency seen at junction of output capacitors.
I get no amplification whatever when power is removed or reversed,
which is what we want.
Except for the AC gain, this appears to be a properly DC biased small
signal transistor amplifier.
On the other sets of amplifier circuits, I see 50 mV pp at junction of
output capacitors.
Could it be that I am using the wrong techniques to view the signal
with my scope, rather than there being a bug in the circuit? I'm
halfway tempted to try putting this circuit in LTSpice as a sanity check.
Scratching my head in confusion,
The Eternal Squire
