Zero potential is not necessarily the criteria that is to be achieved.
The important point is that adjacent pieces of equipment be at the
*same* potential, whether that be at zero or 100 volts potential.
OK, that is an extreme example, but the point is that there should be a
low resistance connection between devices sharing an unbalanced
connection between the two, and that low resistance connection should be
something other than the shield of the audio or RF unbalanced cables.
The easiest way to accomplish that condition is to bond the equipment
from point to point by good heavy wire or braid.
Since we commonly use computers in our ham stations, that is one source
of hum, buzz and other noise. Bonding the computer straight to the
transceiver will cure many ills.
We did not have those problem in older gear where the connectors were
mounted to the enclosure of the equipment, but modern construction where
the input and output jacks are mounted to the PC board causes stray hum,
buzz and noise and RF currents to be coupled to the PC board rather than
being routed to the outside of the equipment enclosure is one of the
primary causes of the problem - that is the "pin 1 problem" that Jim
Brown K9YC refers to.
73,
Don W3FPR
On 12/31/2015 7:44 PM, Bob McGraw - K4TAX wrote:
Don et al:
Well Jim and I are at 100% opposite positions on this point.
Bonding from equipment to equipment is a series circuit in which the
voltage divides across each value of R. Thus none of the equipment
will be at zero potential.
By using a bond conductor from each piece of equipment to a common
point, this provides a star system which is endorsed by most audio and
system design specialists. It provides the lowest resistance as all
conductive paths are parallel.
73
Bob, K4TAX
On 12/31/2015 6:32 PM, Don Wilhelm wrote:
Bonding to a common point may not cure hum and buzz.
Follow the advice of Jim Brown K9YC and bond from equipment to
equipment - following the path of the shields on unbalanced audio
cables and RF coax.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
