fc390 freq. counter

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RBR762
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fc390 freq. counter

#389168

Post by RBR762 »

i know this topic has been brought up before but..........has anyone come up with a fix for the problem of the counter reading a couple khz. off after being modded for a Grant XL/148GTL.
I have 3 of them and only one read spot on after soldering JP1 only.............this is board#EPT210014D
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Re: fc390 freq. counter

#389171

Post by MDYoungblood »

I thought you had to bridge 2 jumpers on that boardJP1 and JP2 for them to work on a Cobra/Uniden radio. I looked at a board on CB Tricks and it shows a trimmer (VC1) that is used to adjust the frequency.

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RBR762
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Re: fc390 freq. counter

#389192

Post by RBR762 »

Tried jumping both and no luck..........the trimmer doesn't have enough range to compensate. Someone on another forum said this is common on these counters and it is a fault built into the microprocessor.

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Re: fc390 freq. counter

#389193

Post by sonoma »

this is the only mod I have ever seen for this counter and never used a 210014 board myself. just make sure you jumped the proper pads.
http://www.cbtricks.com/radio ... 10014d.htm
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Re: fc390 freq. counter

#389194

Post by MDYoungblood »

I've never dealt with one. How close does the variable capacitor get the frequency? Maybe change it to one with more range. I would think the problem would be more on the cheap crystal than the MP since you have one that works fine.

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