I have seen pictures of several SX-28 or SX-28A receivers that have
what appears to be an additional IF stage modification. This mod is
right in front of the power transformer, and has a miniature tube
(6BA6 ?) and an IF can mounted on a small sub-chassis.

I would appreciate any information regarding this modification. A
pointer to anything published would be ideal.

Thank you.

73,
Jeff
N6MNI