In article , Robert Casey
wrote:

If a tuning eye is fitted to this type of radio it is almost universally
connected to the audio detector rather than the AGC detector, which is
unfortunate from the AC loading point of view as the filter for the eye
tube often presents an even worse AC load than the AGC circuit.

Is that because of a resistor-capacitor filter between the audio
detector and the grid of
the eye tube?

Yes

I would just feed the audio directly to the eye tube
grid, and place a
cap on the eye tube triode plate to do the filtering there.

If you feed the audio directly to the eye tube grid, and place a cap on
the eye tube triode plate you would probably get serious flickering of the
eye angle with modulation, as the charge and discharge time constants
would be quite different resulting rectification of the audio.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/