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PostPosted: Wed Aug 03, 2016 12:58 pm 
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Joined: Sat Jul 23, 2016 3:41 pm
Posts: 16
OK, so looks like I need some help/advice.

Just completed the build and doing the Ohmmeter tests, I am getting a reading of 2K Ohms with the power switch off, but 1.5K Ohms with the power switch on.

The MOSFETS appear to be OK, but my meter, shall we say, sucks. Old analog model.

So what should I look for??

Thanks

MJ


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PostPosted: Wed Aug 03, 2016 7:05 pm 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1142
Hi KJ,

1.5k with the switch on is probably OK. 2K with the meter off is a problem. Since it's on analog meter make sure that the red lead is positive with respect to the negative lead (unfortunately you'd need a second meter to do this). You need to make sure that the positive side of the meter is on the positive power lead. MOSFETs have a body diode which means that they conduct in the reverse direction. Try swapping the leads and see if the resistance goes up.

73,
Jim WA2EUJ


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PostPosted: Wed Aug 03, 2016 8:51 pm 
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Joined: Sat Jul 23, 2016 3:41 pm
Posts: 16
Quote:
Try swapping the leads and see if the resistance goes up.


Thanks Jim. That work a charm. On to the rest of alignment routine.

I had no clue regarding the test leads being polar in the analog meters. Thanks for that tip.

MJ


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