"John Proctor" wrote in message
news:2005021307082216807%lost@nowhereorg...
Meindert,

An interesting thing is that STP is almost never used outside Europe.
The company that I used to run here in Australia kept both on their
books but we never sold any STP that I know of. BTW we might have as I
was the MD not the sales manager ;-)

I have a Kenwood D700 Amateur radio (VHF/UHF) in my car. The microphone
connects to the radio via an RJ45. The control head connects to the
radio via an RJ11-RJ12 4 core cable. When you remote the radio (mine
is in the back of a Volvo X70 station wagon where the spare tire is
kept) there is a relatively long run to the control head and
microphone. I used Cat 5e to extend the microphone connection. Works
great no RF feedback, no hum etc. Kenwood made the pinning such that
the mic level winds up on a grounded/active twisted pair. No STP
required. Smart eh!

I agree with you that in many occasions, UTP is fine. Look at our ethernet
networks: UPT up to 100Mbit. I also have first hand experience with UTP in a
factory environment, in an RS-485 network. And probably this HDB2 is RS-485
too. But since the original cables from Raymarine have a shield, why not
replace it with a shielded cable. Maybe the shield is used to keep the
RS-485 tranceivers on the same ground level, to stay within the specs of the
RS-485 chips (-7 to +12V max common mode).

Meindert