[SOLVED] interference on 5k pot

[engineer1000]

I have designed a generator that runs between 116khz to 140khz. The frequency is adjustable using a 5k panel mount pot.
When ever I touch the pot spindle or any of the outside metal work the output of the gen is affected. I have checked the continuity between the metal spindle and the 3 solder tags all hi impedance.
Anyone got any ideas? The gen only seems to work correctly when I'm holding the metal spindle. I have tried earthing the body of the pot but this doesn't seem to do much.

 

[mikerf]

odd.. is the pot DC-coupled?.. I found many moons ago that AC coupling them avoided lots of issues.

 

[engineer1000]

Hi Milkerf,
Thank you for your quick response. No I don't think it's coupled. It's just a standard 5k 10 turn pot from RS Components (RS Stock No. 522-3028)
I am baffled

 

[crutschow]

Is the pot body and chassis connected to the circuit common?

 

[engineer1000]

no it's not

 

[crutschow]

no it's not

Then you might try that.

 

[engineer1000]

Thanks Crutschow , that did it