RadioBanter - View Single Post

August 9th 05, 03:28 PM

On 8 Aug 2005 23:07:14 -0700, wrote:

Hi All,

Does anyone know what's the power gain of a 2N3866 at 9, 12 and 14
volts? I know that the 2N3866 has a gain of 10dB at 28 volts.

C.W.

That must be 1watt out Class C at 400mhz value.

The spec (motorola 1978) Ft is 500mhz @15V and collector current of
50ma. Later manufacture devices have Ft in the range of 800mhz.

The gain is really a function of many parameters and often the given
numbers have to be "qualified" for a given set of test conditions.
The 2n3866 is a high gain device that is useful to in excess of 400mhz
and when used at lower frequencies exhibits the usual Ft/Fop gain
curve( gain at frequency is Ft [where gain is 1] divided by opertaing
frequency and never exceeds the DC or low frequency HFE value).
So at say 40mhz the gain will be around 50 or ~17db.

The gain of that device is tied to frequency and operating current
and circuit impedences more so than voltage. As imagined they are
interrelated. However at 13.6V the class C power gain is around 10db
at 175mhz but at 28V it will be around 13db. In class A or B circuits
the gain numbers have to be derived from the Ft and HFE as well a
circuit topology used. Typically the small signal Class A gain will
be much higher.

Allison
Kb1GMX