Has it ever been determined when (date or serial number) that Hammarlund switched the 160, 170 and 180 to conventional caps in the IF cans ? In your experience did they switch to conventional caps in all IFs in a receiver when they made the change?

I have seen different symptoms described in afflicted RXs, such as burnt resistors and non-tunable cans, but Is there any exterior physical difference in the cans ?

Alan, N3BJ

Hi Alan!!

When Hammarlund went to the standard 3/4 inch IF can, Alltrad used their usual mica sandwich cap in the base of the transformer. I've had the last run of transformers in my hands that were on Hammarlunds shelf, and their cans never used external mica caps across the coil inside of the IF can. The assembly cost of the IF can would have been too much. At least the can is repairable, if the base of the can is disassembled and the mica removed. Then you can place a mica cap inside, or outside, and get things working again. I have a Hallicrafters SX-130 here that used the same IF cans, built by the same company, and they had the same issues. I took them all apart, and replaced the mica stack with fixed external caps, and aligned the set. The thunderstorms inside the radio went away. Its a pain, but it can be done.