On Thu, 22 Apr 2010 11:32:39 -0400, Les Kalmus wrote:
>Some people have reported that the noise is not a problem when using
>coax (i.e., W3LPL).
With either coax or twisted pair, I'd put a toroidal ferrite choke on that
sensing line tuned to the frequencies where noise is a problem. If the
sensing line and the 2-#12 are in the same bundle, I'd wind both of them
through the toroid.
Someone really ought to point the designer of this product to the Jensen
Transformer's website to study Bill Whitlock's classic work on the noise
rejection properties of balanced circuits, and to my website to study RFI
coupled by foil/drain shields of shielded twisted pairs. I would expect this
circuit to be most troublefree with unshielded twisted pair, a balanced
input, and no ground reference at that pulser. It also makes sense to add a
ferrite bead and small value capacitor at the pulser to control waveshape.
73,
Jim K9YC
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