[R-390] backlash on URM-25

[Flowertime01 at wmconnect.com]

Bob,

You may be going the wrong way with your back lash.

My recollection from the late 60's early 70's was the generators always had 
some back lash. You just could not roll up on a frequency and then expect to 
just back up as you over dialed.

You had to have a feel for each generator. You rolled up to where you wanted 
and watched the meters and dial. You made two three passes at it and then 
tried a time or two to roll on the spot you wanted without going over. If you went 
over then you dialed way off and rolled up again. you had to decide if you 
wanted to roll up or down to get the frequency.

But you likely have excess friction in yours that keeps you from getting it 
where you want. When you let go of the knob it wants to change frequency and 
you have trouble getting it to stick as you let go of the knob.

The mobile synthetic motor oil for a lube is in order. You may have to pull 
lots of the mechanism apart and clean and lube every thing. You may have to 
scrape a shaft and file a couple burs to get the guts smooth again. You may have 
a bend in a shaft that is binding from years of shipping and moving. The drum 
should drop firmly on the detents. But as you dial the frequency the knob 
should be easy to turn and smooth.

Getting the mechanical motion of the generator silky is a lot like getting 
the KC change in the receiver to run nice and free.

Some lash adjustment is needed but mostly just to take the slop out of the 
mechanism. Much like not over doing the springs in the split gears of the 
receivers.

Hope this gives you some help getting the mechanical adjustments in better 
condition.

Roger AI4NI


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