[time-nuts] Re: Bruce's common emitter transformer feedback amplifier: oscillations with capacitive load

[Bruce Griffiths]

Excessive leakage inductance can be an issue with some instability evident if the interstage transformer isn't terminated in 50 ohms. A transformer coupling factor greater than 0.95 is desirable for the nominal design winding inductances. A capacitive load is a poor approximation to the impedance presented by a length of unterminated coax at RF frequencies. The impedance can range from open to short circuit depending on the cable length. Saturation and/or cutoff can occur if the input signal is too large for the supply voltage or bias current.

Bruce
 
> On 24/04/2023 02:15 NZST Matt Huszagh via time-nuts <time-nuts at lists.febo.com> wrote:
> 
>  
> Bob Camp via time-nuts <time-nuts at lists.febo.com> writes:
> 
> > A schematic would be a big help here …..
> >
> > Flying blind, best guess is that your output stage has an issue. If the two output bufferers
> > are identical to the input stage, that’s probably the issue. A different configuration for the 
> > buffers would be the most obvious fix.
> 
> Hi Bob,
> 
> I've attached the full schematic. Hope that helps.
> 
> Matt
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe send an email to time-nuts-leave at lists.febo.com