Content-transfer-encoding: 8bit

Has any Decca Jeep owner considered using ferrite cores for PA coils instead of altering the existing poor quality paxolin air wound devices. The originals in spite of being wound with litz wire are poor specimens, not even good quality at the time, when ceramic formers and better were available and widely used in the USA.

Using the original coils the inductance when measured in the case and out of the case varies by several Uh and therefore difficult to resonate/align properly. For those that want to retain the originals there is a way to overcome the problem with resonance, but I have not seen any reference to it before.

Rewind the coils lower in frequency by a few khz than is required and use a large copper ring in the core of the coils for precise resonance, alternatively wind the coil higher in frequency than required and use an appropriate ferrite core to adjust for precision alignment.

The best approach is to discard the original coils and rewind new coils on ferrite cores that do not alter in inductance in or out of the metal cabinet. Each coil consists of the main winding and a link winding. Each coil can be resonated externally with the pull out capacitor board, to the exact frequency required, then replace without further adjustment all three coils/capacitor boards.

Because each unit only runs at about 400 watts rf out, 18 guage insulated wire is adequate.

If anyone is interested in the above mods I have the exact inductance measurements for main and link winding. These values are for the high band versions, low band versions need the capacitor boards modified as well for 136 khz.

These Jeeps are big things, about the same size as the Marconi Jeep, and a quarter the size of the Willis Jeep. A better solution is to build your own micro jeep, more power and a fraction of the size as the Decca.

Have luck de G3KEV