Lewin, at 08:35 on May 20 1995, you wrote to Bill Grimsley...

BG> The FCC rules are specifically designed to provide reasonable protection 
BG> against RFI (Radio Frequency Interference) in residential installations.

LE> There's a hidden fact there too - most appliances say "Class B
compliance 
LE> testing was performed with shielded cables. To ensure compliance, shielded 
LE> cables must be used at all times". Then they go ship a standard
RJ11C-RJ11C 
LE> telco cable with the thing.

That's really no big deal, as your average motherboard generates a hell of
a lot more EMR than a modem does anyway.  My USR for example, is in a
plastic case, yet generates no discernible RFI whatsoever.  Indeed, it sits
less than 30cm from my TS-440S transceiver, and I still use the rig while
transferring files, no problems at all.

LE> Zoom were, for a while, shipping with their V.34 models an ENORMOUS 
LE> plastic-coated ferrite cylinder to put around the telco cables (both in and 
LE> out). People thought it was to suppress external noise to get better 
LE> connects. It was kinda sad to disillusion them. 

I'd be more inclined to suggest that their modems were subject to
interference from external RFI, rather than actually causing it.  That's
the usual reason for using ferrite chokes on the telephone cables.

Regards, Bill
@EOT:

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