[R-390] [KA9EGW] pto ok now?

[Shoppa, Tim]

KA9EGW writes:

> Is this normal, to have asymmetrical overrun?

There's multiple physical end-of-run stops. There's one made of discs right behind
The front panel. This is to prevent you from physically hitting the PTO's end of
Run which could (if you apply too much force) potentially damage it or knock it out
Of kilter. These are the stops that you are supposed to hit!

The PTO's physical range is more than ten turns, but there's an optimal range
Over which the linearization adjustments do the most good, go to the wrong ten turns
And you may not only has linearity gone out of whack, but that it cannot be adjusted
Back into whack.

To "center" the overrun you can loosen the screws on the Oldham coupler turn a
Fraction of a turn in the correct direction, and Rezero the counter. All assuming
You aren't coming close to the internal-to-PTO end of travel.

There's probably also some way to tweak the front panel disc stops, but the Oldham coupler is the usual place.

Most of us have unintentionally had the Oldham coupler screws be less than tight :-).

You're doing great, IMHO, if you've got the thing zeroed and 1000kc is exactly 10 turns.
Before messing with the overrun I'd check the linearity and after adjusting the overrun
I'd recheck it to see if it got worse or better. Could go either way. Adjusting the
Linearity screws on a PTO is do-able but if it's "good enough" I'd say just to leave it.

How good "good enough" is to you I don't know. It is conceivable to linearize
The PTO until it's within a few hundred Hz over the whole dial, but it's a lot of
Tweaking of corrector screws or stacks and charting.

Tim.