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A VFO knob should run smooth and easy. If your knob tend to run slow and feel stiff you better take care of the problem before it is too late. If the knob is completely looked you may end up with a serious problem and a total damage of the VFO. There is a rumour that spare parts is no longer available so fix your problem before it is too late. Remove all connctions from the back of the tranceiver and raise the tranceiver up to a vertical position. I found it easier to work in this way. |
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Remove the rubber ring
from the knob. Undo and completely remove the knob main assy. If you
are lucky the knob can be removed but in worst case you have to use force
to remove the knob from the shaft. If you cant turn the knob you are in deep trouble. When this unit was repaired it took nearly one hour to remove the knob. The knob could not be turned at all. Keep in mind there is no "backdoor" to remove it. |
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When the knob is removed the remaining work is easy. |
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Remove the wires and
opto. This must be done to get the shaft out. Remove the clip from the shaft at the back. Note the position of washers. Carefully push the shaft out from the body. Pay attention to the disc. |
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A completely dismantled
VFO system. Carefully clean the shaft. Note the thinn washer close to the
disc. This is where dirt is accumulated. Clean and polish the shaft. Insert the shaft to the body and make sure the shaft smoothly can be turned. Add some very thinn oil to the shaft. Again, pay attention to the disc it is very thinn and fragile. |
Assemble in reverse order, Good Luck. |
MFJ-269 Antenna Analyzer, a solution to the 27.9v problem, go here.
Drake R-4C: How the filter leakage problem can be solved, go here.