I’m restoring a GE Model F-80 radio (c1938) which has had a lot of repairs done--perhaps shortly post-war as parts became available ( “10/31/46 is penciled on the chassis). I need advice on one of the IF transformers.

Here’s what the third IF transformer looks like. I’m guessing that the burned dog bone resistor is a replacement part, but the schematic also shows a second mica capacitor.

https://lh3.googleusercontent.com/-yZWmdnL0IjE/VcvLmBqdJSI/AAAAAAAAO7c/_p5zssOlUF8/s520-Ic42/GE%252520F-80%252520%252520212.JPG

Below (left) is the original schematic with my re-drawing of the current status (right).

https://lh3.googleusercontent.com/-y3e_j3vtMTo/VcvLmvD8_bI/AAAAAAAAO7o/PXVbEqarJjQ/s520-Ic42/GE%252520F-80%252520209.jpg

So, should I restore to the original specs--replacing the dog bone and adding the missing C-28? If I add the missing C-28 I’ll replace C-27 as well, but what should I use as replacements. I have available 500V silver-micas, 630V polystyrenes, and 1KV-6KV ceramic disks.

Thanks (but be warned that I’ll be asking about the dreaded Candohm resistor at some future time).

(Replying to my own post... Is this a sign of early dementia?)

I decided to use the configuration on the schematic and replace the 250pF mica cap which tested about 300pF, so I fabricated two new 250pF caps using 100pF and 250pF 500V polystyrene caps.

https://lh3.googleusercontent.com/-ut8EvyflIzM/Vc7ug7bSSRI/AAAAAAAAO9E/Hggo15373qE/s540-Ic42/GE%252520F-80%252520211.jpg

Intuitively I avoided placing the components between the coils. This little job took me a full three hours, but that included the time it took to fix the coil connection that I broke and to replace the terminal that I broke on the underchassis side of the transformer.

https://lh3.googleusercontent.com/-IaH_JZwpuR8/Vc7uh_cw5MI/AAAAAAAAO9M/bG-5DfpIcUU/s540-Ic42/GE%252520F-80%252520213.jpg