[GreenKeys] Frequency Selective Limiter??

[Jim Haynes]

Interesting.  I have no idea what it is.  However I know a weakness of
a lot of early RTTY setups, both ham and commercial/military, was that
they depended on the receiver bandwidth for pre-limiter filtering.
A limiter does you the most good if you can make the desired signal
stronger than any interference, since a limiter suppresses the weaker
signal(s) present at the input.  So it would be good to have a twin-peak
filter ahead of the limiter; and this device might be something that
does just that.

Would be good if you can run frequency response on the filters to see what
they do, and put tubes in the thing and power it up to see what the whole
thing does.

To go a bit further, Prof. Elie Baghdady at MIT circa 1960 published
some papers on the desirability of using positive feedback around a 
limiter, to the point where the circuit barely oscillates in the absence
of input signal.  He didn't apply this to FSK so far as I know, but
it should work.  And I remember breadboarding a circuit back in the
late 1950s and using it in an RTTY contest, but didn't do any kind of
comparison with and without feedback to see how much it helped.

I'd really like to know what you find out about this, for the sake of
RTTY history.

 	---

 	"Ya can argue all ya wanna, but it's dif'rent than it was."
 	"No it ain't! No it ain't!  But ya gotta know the territory."
 		Meredith Willson, The Music Man