Another quick 2N3904 test

I saw a schematic on the web that I wanted to validate....

The original article that I was reading suggested something like 15-17dB of gain.
I thought that was a little optimistic for a circuit with only DC bias. I expected
it to be current hungry and to be closer to 15dB of gain based upon some other tests
that I had run with similar components.

I did not go crazy with a wide range of test scenarios. The circuit is looking for
an input drive level of -10dBm to +10dBm. The circuit is pretty hungry at 57mA with
only 13.5 dBm of gain.

Some simple tweaks should be able to cut the current in half while pushing up the
gain some more while in class A operation.

Please see my notes at:


Oh yeah... I know that I need to come up with a bifilar transformer icon.  :-)

I had the parts on hand so it only took about 15 minutes to bread board it and
test it with the signal generator and power meter.