[time-nuts] Re: Isolation amp transistors

[glenlist]

how about grounded grid ?

Bob can you get  better isolation with a vaccuum tube cascode than a 
solid state cascode ?

-glen

On 07/07/2022 15:22, Bob kb8tq via time-nuts wrote:
> Hi
>
>> On Jul 6, 2022, at 1:53 PM, Richard Karlquist via time-nuts<time-nuts at lists.febo.com>  wrote:
>>
>> The 2N5179 has high base spreading resistance (decreases isolation).
> As does sticking a resistor (even a small one) in series with the base …. Yes, inductance
> is even worse.
>
> For “best isolation” in a cascode you very much want the base of the common base
> stage nailed to ground. Typically “lower” Ft transistors with a decent base structure
> are the best choice for the common base stage. Both stages benefit from low 1/F noise
> in the audio range if this is for a phase noise test se
>