Bush AC81 Tuning Bush/spindle. Dismantle or normal for this tuning?

[BrianAllen]

Please see attached photo.

The spindle/shaft moves very freely when turned for fine tuning but the brass section is very stiff to turn. I have noted on a GEC that I have, that it is also very stiff to turn.

Is this normal for this arrangement or do they need stripping down, cleaning and lubricating?

Thank you.

Brian

[crackle]

This is a slow motion drive system. If the smaller 1/4 inch spindle is the one that the tuning knob fits on and if this turns freely and moves the tuning capacitor vanes and pointer easily with out binding then all should be OK.

Mike

[BrianAllen]

Thanks Mike, I will have a better idea of how freely it moves when I put the set back together.

Brian

[Graham G3ZVT]

the mechanical advantage that the slow-motion drive gives you becomes an encumbrance when operated in reverse.
Think of a bicycle or a gearbox.

Looking at a picture of the AC81 it does not appear to have a concentric coarse tuning knob, so all things considered, I think it's behaving as expected.

[FERNSEH]

rambo1152 wrote: "Looking at a picture of the AC81 it does not appear to have a concentric coarse tuning knob, so all things considered, I think it's behaving as expected."

A similar tuning mech was used in the DAC90, BA91, SUG3 etc.
The attachment shows the slow motion tuner components on the SUG3 chassis I'm modifying to create a BA91.

DFWB.

[BrianAllen]

I will take another look at a GEC which has the same type of tuning arrangement before I take another look at the Bush AC81. The brass bush inserted into the steel just doesn't feel right to me; not smooth operating at all.

Brian