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Title: Johnson Ranger 1 problem Post by: K8DGL on August 05, 2011, 10:01:44 PM I just picked up a Viking Ranger 1 with a problem. Seems I can only get audio with the audio pot in one presice spot. Sounds like a bad pot, but I have checked and cleaned it and checked it again. Tubes all check OK. Voltages all OK. Any ideas?
Title: Re: Johnson Ranger 1 problem Post by: k4kyv on August 05, 2011, 10:22:22 PM Before ripping out the pot and replacing it, try squirting some WD-40 into the pot housing. That has worked for me, even after contact cleaner failed to improve anything.
Title: Re: Johnson Ranger 1 problem Post by: K8DGL on August 05, 2011, 10:27:11 PM I have sprayed it with tuner cleaner with lube. Smooth reading on the ohm meter while turning shaft.
Title: Re: Johnson Ranger 1 problem Post by: kb3ouk on August 05, 2011, 10:42:52 PM if i have a pot that acts like that, i turn it back and forth a couple times to try and maybe get any crap on the contacts wiped off.
Title: Re: Johnson Ranger 1 problem Post by: AB2EZ on August 06, 2011, 10:25:28 AM Check to see if the coupling capacitor between the output of the first audio preamplifier stage and the top of the potentiometer is working properly. If it is shorted or partially conducting, this would place a DC bias on the grid of the 2nd preamplifier stage... whose value would be very sensitive to the setting of the potentiometer.
Stu Title: Re: Johnson Ranger 1 problem Post by: Knightt150 on August 08, 2011, 05:31:21 PM The best way to check the pot is to remove the wires on the center and one end and put a ohm meter on it and run it through its paces, that will tell the story.
John W9BFO Title: Re: Johnson Ranger 1 problem Post by: ke7trp on August 08, 2011, 10:29:30 PM This is a right of passage with a ranger 1 or valiant. The Audio pot and the Driver pot fail. Order new Clarostat pots and replace both at the same time. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Good advice on the cap also! C |