Transmitter Maintenance - RT's Radio Home Page
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Transmitter Maintenance
Amateur Radio > E.F. Johnson Restoration
Transmitter Maintenance
Once the Ranger and Valiant are initially restored to good working order and kept in a climate controlled environment, dust is likely the main culprit. Best to keep the rig covered when off line for extended periods. Of course, lubricants in the various shafts degrades over time and must be reapplied. Periodic cleaning of the rectifier tube sockets and area around them is advisable whenever the case is removed.
Viking 500 Fan: The original Viking Five Hundred fan motor needs lubrication at least once a year. Though it is a fiddly task to remove the fan from the chassis, it is best to do so to properly lubricate it. It has an absorbent material for retaining oil at each bearing. Perhaps more frequent lubrication is warranted depending on the accumulated hours of operation. A modern fan/motor that requires no periodic lubrication could be installed; however, the fan blade may not line up with the with the intake hole in the bottom cover. Be certain it is made for drawing air into the transmitter.
VFO Drive and other controls:
The grease in the VFO reduction drive dries out after several years. It should be very smooth and positive in operation. If not, it likely needs dismantling, cleaning and re-lubrication. **When dismantling, make a chart showing which parts go where**. To dismantle, the threaded portion of the drive must be gripped to allow the nut to be removed. To protect the threads, it is best gripped in a vice using a piece of scrap aluminum sheet between each jaw face and the thread.
When this drive is cleaned and re-greased, use a generic plain grease. Avoid using Lubriplate--it is so slick, the drive will slip. (I know this from experience.) Reassembling, the drive mechanism requires a small amount of preload; too loose, and the drive will slip and be difficult to set the VFO frequency; too tight and the drive may be permanently damaged and become rough in operation. Again, use the vice with sheet aluminum strips to protect the threads. Setting the preload takes some experience.
