Farhan,
the gain tested correct with a sag in gain attributable to frequency but the -1db compression
was at a lower than expected level at 45mhz than at 12mhz.? About the same difference as
the actual measured gain or about in the test case breadboard 6db.
What I got was 19.6 (almost 20db) at 12mhz, at 45 it was down to 13.9db and the
-1DB point tracked that.? ?Also the S11 degraded? significantly for return loss of?
16db at 12mhz dropping to less than 10db at 45mhz.??
With 2n2369 those improved both gain, flatness, and return loss.
Went back to 3904s and Wes's circuti and set the gain to 15db and saw near flat?
gain (-2db at 45mhz), improved -1db compression and better than 14db return
loss at 45mhz.? It was still better at 12mhz only by a 2db.?
Simple answer your pushing for too much gain from a device that cannot do it.
also higher operating current had a negative effect on compression point as
it was not linear.
The 3904 is a great utility device.? It has two limitations 300mhz FT but at
low gain its fine.? The other is at more than 10mA its HFE falls, this means
increasing the current does not help its gain and may lower its compression point.
Allison
