On 8/7/2020 3:11 PM, Steve Maki wrote:
If it's the 60 Hz field being close to the other cables that you're
concerned with, just de-energize the AC cable when not needed.
I have some some 120V AC lines in the same conduit as my rotator and
relay control lines, with direct buried Heliax just above and below the
conduit (up to to 500' runs), and have not noticed any issues. Normally
I only energize the AC when I need to do some soldering or run a capstan
winch out there, but sometimes forget to flip the breakers off for
extended periods.
There should be no magnetic field issues with AC running next to other
cables as long as the AC cables are twisted pair (or twisted triplet)
and there are no double-bonded neutrals. That means, for example, that
neutral must NOT be grounded anywhere except back at the breaker panel
where the system is established (usually were power enters from the
street).
Indeed, to minimize crosstalk, twisted pair has been good engineering
practice since the earliest days of telephony. In the pro world,
virtually ALL analog audio is carried on twisted pairs. Think about it
-- in those early days, telco lines, including broadcast circuits, ran
on the same poles as power across the country. Since the interfering
signal was 60 Hz, the voice pairs were crossed over every other pole.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|