[ARC5] ARC-2: IF Regeneration is a "No"

[Bruce Long]

in this case the negative impedance generator(s) would be connected to the if filter poles.  If designed correctly the negative impedance converter would generate a pure negative resistance with a small or zero reactive component.  For this reason the filter frequency would not shift and tracking would not be affected. No extra tracking stuff is required if the negative resistance generators generated a pure, reactance free impedance.

I am sure this could be made to work,   but that does not mean it would be worth the effort.

However I think you might have to reduce the coupling capacitance to gain the bandwidth reduction advantage of decreasing the filter pole load ( thereby increasing the filter unloaded Q)


On Wednesday, April 2, 2014 6:04 PM, Bill Cromwell <wrcromwell at gmail.com> wrote:
 
Hi Dave,

A negative impedance  generator whether it is vacuum or soild state is 
also known as a Q-multiplier. The IF amplifier device is not the active, 
regenerative, Q-multiplying device. The Q-multiplier is a separate 
active device and would typically be connected at the IF (or RF) amp's 
plate circuit. I don't know how much that would influence the tuned 
frequency of the IF amplifier. They *have* been used on the tracked rf 
ampliiers in the front end of receivers to help suppress images and 
other out of band energy. I would be very skeptical in the case of your 
receiver's IF. You would have to add tracking hardware to an additional 
active stage whether or not it's tube or transistor based. I think those 
work better and are more stable than a regenrative IF or RF amplifier 
and would be best at some fixed IF frequency. The Q-multipliers are 
regenerative but the feedback is held below the point of oscillation. If 
you add enough knobs and linkages and belts and chains and hoses you 
could make it work in a Frankenradio.

YMMV.

73,

Bill  KU8H

On 04/02/2014 12:06 PM, David Stinson wrote:
>
> ----- Original Message ----- From: "Bruce Long" <coolbrucelong at yahoo.com>
> ---snip------

> -----------
> You might consider making a simple solid state negative impedance 
> generator to introduce resistive regeneration. This way the filter 
> tuning should remain unaffected.
> -------------
>
> I've no knowledge of this concept.  I looked it up in
> Wiki but I'm not "connecting the dots."
> Can you please give details of how this could be
> implemented in the IF circuit?
> Thanks, Dave S.

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