[ARC5] R-25 dial nonlinearities

[Jim Falls]

I had trimmer cap fits when aligning my BC-312-L. All the RF stages use the same style 4-vane semicircular straight line trimmer. It's bloody murder getting the uppermost band set: the cap is far too sensitive to minuscule shaft movements. I ground down a screwdriver so it fitted the slot precisely, then used a mini vice grip with a popsicle stick handle (torque wrench style) to get close. I wonder if a custom tool was used?

Even then, I had to leave the "clamp collar nut" merely snug. Tightening it threw everything off. I finally had to walk away before I took a hammer to it. It's reasonable at 16-18 MC, but not worth bald spots to get any closer. 

Cheers!
Jim K6FWT

> On Jan 8, 2017, at 11:33, Robert Eleazer <releazer at earthlink.net> wrote:
> 
> I've been trying to align a National NC-270 and I'm having a dial nonlinearity problem.  I get the frequency set on the top end of each band and the bottom ends are always off.  The receiver has a sliding dial so you can align it as required by using the 100 KHZ marker signal.  But the amount it is off can be beyond the ability of the dial to slide.  You set the coils for the top end of each band, but there is only one trimmer cap for all the bands.  I plan to add some individual trimmer caps for each band and see if that helps.
> 
> Wayne
> WB5WSV          
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