[ARC5] Suppressor connection in ARC-5 receivers.

[Kenneth G. Gordon]

I have been very curious as to why the engineers at ARC connected the 
suppressor grids in the IF stages of their receivers to the cathodes externally, 
yet used variable cathode bias for gain control in those stages.

When I broached a question about the effect of doing this, no one could 
provide an adequate answer, and I most certainly had no idea either.

Reading a PDF article on the use of diodes found in an article originally 
printed in 73 Magazine back in the 1960s, I found this statement:

"If the suppressor grid in a high-gain pentode is disconnected from ground, 
the tube will oscillate..."

This was followed by a very simple diagram detailing a diode connected 
between the suppressor grid and ground, supplied with a variable, controlled, 
forward-bias, making the stage regenerative, enhancing selectivity, and 
providing a "BFO" for those receivers without one.