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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WA1QHQ on January 28, 2018, 05:56:23 PM



Title: Johnson VFO Reduction Drive
Post by: WA1QHQ on January 28, 2018, 05:56:23 PM
I have a Valiant that has slop in the reduction drive for the VFO. Has anyone rebuilt one of these before and if so a procedure would be appreciated. Does Johnson actually build these or are they a purchased part?

Mark WA1QHQ


Title: Re: Johnson VFO Reduction Drive
Post by: W1RKW on January 29, 2018, 04:51:24 PM
I'm not familiar with the drive in the Valiant but if it is a Jackson type ball drive which it may very well be, don't disassemble at first. Try to relube it with some oil and see what happens. If that doesn't work, soak it in a grease dissolving solvent then repack it with a multi purpose grease. I won't be easy to repack but it can be done. If the slop in the drive doesn't go away then disassemble, clean and repack. When reassembling, don't sock down the spring washer to tightly when recrimping. Do it gradually until you get the best result.  It's possible to purchase Jackson reduction drives if you don't want to bother with a rebuild.

Also, some times, when reinstalling into a rig, getting it lined up properly with the capacitor shaft so it doesn't bind can be tricky.


Title: Re: Johnson VFO Reduction Drive
Post by: wb6kwt on January 30, 2018, 08:35:45 AM
Mark, there isn't much to the reduction drive but it's a BIG job to take it out. The front panel has to come off. The phonelic insulator is very easy to break so be very careful, it's best to remove the screws from the shaft before removing the front panel. Once you have it out it's probably going to take some effort to get it apart. There are small ball bearings in there so be sure to hold it over a container. Here is a good write up explaining how to remove the front panel. http://freeradiocafe.com/forum/viewtopic.php?f=14&t=4979#p7398

There is a good youtube video, from D-Lab, explaining the process but I can't seem to find it right now but it's there somewhere.

Bob -wb6kwt
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands