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Constant loud hum or buzz on receive #ubitx-help #v5

Gavin
 

I just wired up my uBitx v5 and on the table it is outputting a loud hum or buzzing that intensifies when I move my finger closer to the ground wire of the volume control. I am new to electronics and radios in general. I asked a previous question about receiving Ashhar Farhan said I may have floating ground, but I'm unsure of how to test for that and how to fix it. Doing other reading, maybe it has to do with my power supply? I just have 12v 5a power supply from amazon, although I don't know if would cause such a loud hum. Anyone have any advice?

Thanks!
Gavin KI7WNX

Gavin
 

I don't know if these will be helpful, but here are couple photos.

 

Hi,

If you have a multimeter, take the analog connector off the bitx and then with the meter set on ohms, check to be sure you measure the pot value resistance across the yellow and green connections.  You can also make sure the center wiper connection vaires the resistance when moving the shaft with the meter on the yellow and orange set and the orange and green set.  It's possible there could be a cracked trace or bad rivet connection on the pot.

Also make sure the spring contacts on the connector plug look good when looking into the end of the connector.  Sometimes the springs get bent down so that they don't make good contact with the pins.

You do have the CW keying resistor installed so the rig doesn't go directly to TX on startup?

73,


Mark.

_Dave_ K0MBT
 

I would look at your power supply first. It is probably a switching power supply and the power getting out of it is not filtered enough. Try using a 12v battery as a test to see if the hum diminishes.
--
73
Dave
k0mbt
Raduino bracket and Ham_Made_Keys

Mike Short
 

You do not have a common ground. The mic, key, antenna shields and power should all be connected together. Put it in a metal case and your issues will probably go away 

Cory King
 


Put it in a metal case and your issues will probably go away 
I wonder if you could test the "common ground" theory out by just using a wire to ground one jack to another and see if it causes any change?  If it does, you might be onto something but do note that there are lots of folks running this thing inside plastic cases.

On my rig, I've noticed that that volume control wire is pretty sensitive and if it rests across the wrong thing, I get a hum/buzz.  I say this 'cause in one photo the OP has the power switch wire near the volume wires.

Gavin, have you tried just jiggling all the wires & jacks and seeing if that changes the nature of the sound?  Sometimes a little percussive maintenance is all that is required :-)

Gavin
 

Thanks for all the suggestions so far! I will try them out and see what I come up with. Hopefully I'll figure it out and post back to say what I had to do.

Gavin
 

I finally got it in the metal chassis and it doesn't hum any more :) Thanks! (although I'm still getting those loud broadcast stations, but I think the suggestions here will solve it)