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Tuning POT not tuning

 

As the title states, my tuning pot does not tune. When I power the BITX40, it starts off on a freq. of 7.700MHz and then decreases, by itself to 7.600, 7.500, 7.400 etc until it gets to about 6.900mhz. It then occassionaly fluctuates to 6.885mhz or something like that. Any ideas?

Raduino version is 1.01 on startup/
 

I should also add that when I go to tune, nothing happens. I can hear a signal coming through my earbuds though.
 

Measure the voltage at the center pin of your tuning pot to ground using a voltmeter. ?Does it smoothly vary between 0 and 5 volts as you turn the knob?

Odd that your rig powers up at 7.7mhz, but frequency going down in 100khz steps is what I would expect if the center pin of the pot was stuck at 0 volts.?


On Sun, Mar 26, 2017 at 11:35 am, Daniel Acevedo wrote:

As the title states, my tuning pot does not tune. When I power the BITX40, it starts off on a freq. of 7.700MHz and then decreases, by itself to 7.600, 7.500, 7.400 etc until it gets to about 6.900mhz. It then occassionaly fluctuates to 6.885mhz or something like that. Any ideas?

?
 

Thanks. I checked the tuning pot with a volt meter, and it read .08v. I took it out of the mounted position just to find out that it was broken. I will buy a new pot and try again. Thanks for leading me in the right direction!
Michael Davis
 

My guess is a wiring error in the vfo circuit. Maybe you used the old and new vfo together somehow. Re-read the directions and maybe take a photo of your tuning pot and associated wiring.

Sent from Mike's iPad WA1MAD
 

Ok, we can close this topic now. I went to Fry's, bought a 10k linear pot. Replaced my broken one, and it works like a charm now. Thank everyone.
 

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A thought, are you using the pot that came with the rig? A number of folks have gone to the 10 turn pots and not realize that pin 3 is the wiper.

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v/r

Fred W4JLE

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From: [email protected] [mailto:[email protected]] On Behalf Of Daniel Acevedo
Sent: Sunday, March 26, 2017 3:11 PM
To: [email protected]
Subject: Re: [BITX20] Tuning POT not tuning

?

Thanks. I checked the tuning pot with a volt meter, and it read .08v. I took it out of the mounted position just to find out that it was broken. I will buy a new pot and try again. Thanks for leading me in the right direction!

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