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Post by brownbomber72 on Sept 5, 2022 17:31:16 GMT -5
Picked up a dirty but nice Mark 3 over the weekend for $100  It does receive but the dial wheel is out of whack with the tuning capacitor. What is the procedure for getting this lined back up? |
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Post by 2600 on Sept 6, 2022 0:27:13 GMT -5
The dial has a vertical line at one end of the scale. Can't remember which end. You're supposed to turn the knob to the end stop in that direction and loosen the allen screws on the dial hub so that line sets behind the fiducial line in the window. If it's already close, no need to disturb it.
Once that's done, there are two electrical adjustments inside. Behind and inboard from the main tuning capacitor is a coil with a hex-shaped hollow adjustment core, or "slug" that's threaded to ride up and down inside the coil when turned with a PLASTIC tool. Can't use a metal Allen wrench. The position of this slug determines how far the dial will cover end-to-end. To the left of this coil is a white ceramic trimmer capacitor with a screw slot at its center. This serves to shift the dial left and right, to line up the receiver frequency with the dial markings. But only if the dial is already covering the right count of channels end-to-end.
That's the short version. If you turn the white ceramic trimmer cap and the receiver frequency doesn't seem to change very much, that trimmer cap may be bad. We see that fault from time to time. If that trimmer cap goes bad it will throw the dial coverage way off by itself. Best to leave that coil alone until you know if that trimmer cap is working. If the trimmer has gone bad, you may not need to touch the coil adjustment when the replacement trimmer is in place.
And then it's always possible someone has reached inside and tweaked it out of whack.
73
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Post by brownbomber72 on Sept 6, 2022 18:18:44 GMT -5
It does have a hole drilled in the top cover that is pretty well in line with the trimmer. I will get the dial back right and then go from there.
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Post by 2600 on Sept 6, 2022 23:25:59 GMT -5
It does have a hole drilled in the top cover that is pretty well in line with the trimmer. Um, kinda gives me the feeling that a prior owner had trouble with that adjustment. Seems kinda radical to cut a hole in the top cover, but some folks go to extremes to avoid having to find a part and replace it. If that adjustment had been stable and reliable, it would never have needed a hole drilled to make tweaking it easier. Barkett sells that trimmer cap here: stores.goldeneagleradios.com/3-12-pf-variable-trimmer/73 |
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It does receive but the dial wheel is out of whack with the tuning capacitor. What is the procedure for getting this lined back up?
