[R-390] The R-390A IF transformers internal resistors.

[Jacques Fortin]

Hi all,

 

I am still working on the last R-390A that followed me home.

This one came with a Stewart-Warner IF deck (Order # 42428-PC-59-A1-51).

When I began to check everything into, it became obvious that a previous
"owner" removed all the resistors within the IF transformers.

The windings test all OK and the caps looks like the original ones, so it
may have been an attempt to "boost" the IF gain.

My question now is: what are the proper values of those resistors ??

I checked for the ones used in my Moto '56 and in a spare IF deck from
Capehart '61 contract and the results were:

Moto '56: R511, 512, 553, 554 : 47k ohms R522: 82k ohms.

Capehart: R511, 512, 553, 554 : 39k ohms R522: 68k ohms.

 

So, why there is a difference between the different makers / contracts ?

Which values should I use in the Stewart-Warner ??

I was unable to find anything in the Wu Li's "Pearls" section.

Does somebody already had documented these values somewhere ?

 

73, Jacques, VE2JFE