[RFI] NOISE GADGETS

[Tom Rauch]

> 1.  Twisted pairs are most effective at minimizing common
mode effects at
> low frequencies.  Ma Bell (remember her?) used 600 ohm
twisted pairs for
> the station wiring for a very long time.  'Real" telephone
wire IS made of
> twisted pairs.  The twisting is why you can hear the
person on the other
> end, and not 60Hz hum.  However, the twisting will not
prevent the coupling
> of RF into the telephone device.


....and nearly all telco RF problems I've found are from
common mode, NOT differential mode, problems.

That means twisted or not, shielded or not, CAT 5 or speaker
wire, there is very little difference for RF.

> order.  On the other hand, I am convinced that, with few
exceptions, most
> of the available consumer telephones today are junk as far
as RF
> susceptibility.

Amen. But a pair of 1000uH series chokes and some .001
bypass caps from line to line work wonders.

73 Tom