[RFI] treadmill noise

[Jim Brown]

On Fri,2/26/2016 6:20 PM, Lionel Booth wrote:
> Hi Jim,
>
> Yep, I mounted the Delta inside of the enclosure with the electronics 
> and the motor.  The PWM controller I think is the source of the noise. 
>  I had 30 over noise in 5 -10 kHz wide every 15 to 30 kHz ( this may 
> be off a bit, it's been a while) from 40 meters through 12 meters. 
>  Since the treadmill was in use during the day I didn't look on 80 or 
> 160 but suppose it was terrible.

Can you look at 160 and 80? I think that's where David's problem is.

>
> At first I tried clamp on Palomar chokes on the half inch power cable.

Those are not "Palomar" chokes, they are Fair-Rite VHF clamp-ons that 
Ralomar resells (and at obscene markups).

>  At six chokes, one pass, 43 mix, I found almost no improvement. 
>  Clearly not enough impedance.

No surprise -- those are NOT common mode chokes below 50 MHz!  They are 
VHF chokes. I suggest that you study k9yc.com/RFI-Ham.pdf

> The Delta took the interference down below my local noise level.  The 
> cost of the big clamp ons or toroids quickly exceeds the cost of the 
> delta.

Of course -- you didn't understand the technique, so you bought the 
wrong parts and used them incorrectly.

>  I did try winding a choke and putting inside the enclosure on the ac 
> line.

How many turns?  What was the core?

> This helped but not enough.  I seem to recall the delta is a balanced 
> pi section filter rated at 20 amps: the circuit is on a 20 amp CB.

Installed the way you did it, the Delta should work pretty well.

73, Jim K9YC