[GreenKeys] Range setting on Model 28 and Model 35 Machines

[WA5CAB at cs.com]

Eugene,

To answer your magnet question (and this applies as well to M14/15 with both 
pulling (60 MA) and holding (20 MA) magents), if one of the magnets were wired 
backwards, the two magnets would buck each other and the selector mechanism 
just wouldn't work.  The results would be analogous to trying to connect two 
identical batteries in series and getting one backwards.  There would be no 
current flow through the load.  It isn't a perfect analog as the insulation 
resistance of space is orders of magnitude higher than the reluctance of space.  But 
near enough to explain what would happen.

My guess is that if you get the loop current back up to 60 MA where it 
belongs, the optimum rangefinder setting will drop back down toward 60 where it 
ideally belongs.

Wild thought - I don't know the vintage of your loop supply but if it has 
selenium rectifiers, replace them with silicon and turn the loop current adjust 
to minimum before you turn the supply back on and then adjust it up to 60 MA.  
If the rectifiers are silicon, check whether one is open (there may be either 
two or four).  If not, then check the filter capacitors.

In a message dated 8/25/2006 9:44:17 PM Central Daylight Time, 
ehertz at tcaf.org writes: 
> Hmmm. good point. I will check it out more tomorrow. The 90 that I arrived 
> at was just a random number that seemed to give good print with the lpr on. I 
> will however try to find the real center of the "good" range to see what the 
> most optimal number really is. If you are right and if there is still 
> something else wrong, I wonder again, if it could be that I have some selector 
> magnets out of phase?
> 

Robert Downs - Houston
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