The K-Tran was a high-tech IF transformer in the 1950s. It is designed first to shield the magnetic field inside the can, so you can put them close alongside one another inside the radio. This is done with a so-called "cup" core of ferrite that surrounds the coil inside. Older IF transformers had to be spaced farther apart to prevent magnetic coupling between adjacent transformers.
The internal frame is made from clear polystyrene. A plastic that shrinks and becomes brittle with age and exposure to heat.
The fatal flaw is the internal capacitors. To make each coil inside tune the proper frequency a capacitor is built in the bottom of the can. It's made from alternating layers of metal and mica sheet. A 'V'-shaped steel spring presses the layers tightly together. A brass rivet at the bottom is what holds the steel spring against the stack of capacitor layers.
It's a genuine high-performance component. The plastic frame has a very low RF loss, the stacked-plate capacitors in the bottom have a lot of surface area, making the capacitor's internal resistance low. This increases the "Q", or selectivity of the tuned circuits inside.
Until age catches up with the polystyrene plastic. As it shrinks the stacks of capacitor plates begin to separate. The loss of tension pressing them together becomes a random on again/off again problem as small temperature changes cause the parts to shift around against one another.
Simply replacing those internal capacitors should fix the problem, right?
Easier said than done. Not totally impossible, but labor intensive. And if that brittle plastic frame comes apart while removing the brass rivet, it's Humpty-Dumpty time.
No easy answers to this dilemma.
73
