[Heath] A possible AR-3 "upgrade"...

[Kenneth G. Gordon]

Although the AR-3 manual states that all the selectivity AND sensitivity is 
generated in the 12BA6 IF amp stage, reducing the noise from the 12BE6 
mixer MAY enhance receiver sensitivity on the upper bands.

Replacing the 12BE6 with a 12CS6, which has double the 12BE6's 
conversion-transconductance (950 umho vs 450), may make a significant 
improvement in receiver sensitivity on frequencies above 10 MHz.

The two tubes have identical base diagrams and filament requirements, so 
all one has to do is remove the 12BE6 and plug in a 12CS6.

I have not yet tried this, but intend to as soon as I get an AR-3 working 
properly here.

I HAVE replaced a 12SA7 with a 6SB7Y (and resistor) in another receiver 
and it did make a significant improvement in that receiver.

Ken W7EKB