[Boatanchors] Tube reciever design banter

[Drew P.]

Carl wrote:

"Dual triode mixer in a Pullen circuit. 6ES8 preferred as its a very
unique variable mu tube."

Presumably since the mixer section of the tube in a Pullen circuit is biased in a very non-linear portion of its characteristic curve, use of a variable mu triode would make operation even more non-linear.  More non-linearity would make for a mixer having better conversion gain.

How much better in conversion gain and other performance parameters is a variable mu triode as compared to a (relatively) constant mu triode when either is employed in a Pullen mixer circuit?

How much better is the Pullen circuit with its intentional biasing for non-linearity as compared to a non-Pullen triode mixer (such as the mixers in the R-390 series)?

Carl, thank you for your insights on these topics.  It is good to get information from someone like you who was in the field and obtained practical knowledge in tube electronics.

By the time I took EE courses, tubes were regarded as hopelessly passe, and none of the professors cared answer my tube questions (even outside of class time), instead they invariably expressed relief that they didn't have to deal with thermionic technology anymore. 

Drew