[Ronja] worst-case with Q103 in the receiver?

[Thomas Egenhofer]

> > (i'm just asking because i had the very same problem with my own
> > receiver circuit of a slower, low-cost fso)
> > it's about Q103 in the receiver.
> > from what i figured out it's why you have to limit the receiver for
> > short-distance links.
> > well isn't it possible that the BE-voltage of Q103 can swing into a
> > negative value ( if the signal is strong enough.. means about
> > 2xVbe-pp(>~1,4V)and more).
> 
> The circuit is designed to cope with this case. When the BE voltage is
> negative, the transistor just turns off.
ah... now i see.. guess i messed up np-transitions again... stupid me.
which makes me wonders again why my rec. was chocked...


> The low distance tuning is not because of the end transistors. It's because
> the NE592 doesn't seem to like too strong signals. Or maybe the Q101. I am
> not sure. I am trying to improve this with my new all-transistor design.
sounds good =). i cant bring myself to trust in ic's after all (except
logic)


> Though it's difficult. Imagine you want to genetically engineer a musician to
> be able to hear a flute over 1.4km, but at the same time to be resistant to
> damage when someone places a gun next to his ear and pulls the trigger.
i know^^ i'm fighting the same problem but since your signal is digital
it is possible. oh and try band-passing (or at least high-passes). they
sometimes greatly help to avoid overdriving the amp from low-frequency
noise.