The number of tragedies in my life suggest otherwise, but in this case, I must
live a charmed life.
I have never had RFI issues while using zip cord for speaker wiring in and
around my ham shack. I have used the red/black stuff for DC wiring but lately
I'm using 10 AWG wire made for low-voltage landscaping use. I also use it for
connecting the speakers in my audio/video system. The only downside is that the
insulation is very thick since it's appropriate for direct burial and I have to
shave it down a little to get it into the abysmal Power Pole connectors that are
standard on too many devices these days.
Wes N7WS
On 8/11/2016 10:11 AM, Jim Brown wrote:
Over the years, I've bought some of the red/black zip cord at hamfests. While
I have not measured any of it with a micrometer, my strong impression has been
that it IS smaller than labeled.
More to the point -- zip cord is TERRIBLE cable for loudspeaker wiring because
it has very poor RF rejection. It has been well known for more than 120 years
that twisted pair has quite powerful rejection of all interference, from a
few Hz to high RF. Think about it -- for the first 100+ years of telephony,
telephone wiring ran EVERYWHERE on the same poles as 60 Hz power lines with no
interference. Their ONLY measure to reject 60 Hz was to have the telephone
lines cross over each other every few poles along the run. This was enough of
a twist when the only interference was 60 Hz. Even today, there are huge
quantities of telephone, intercom, and even audio wiring carried on unshielded
twisted pair. CAT5/6 carry high data rate signals on opposing pairs without
interference. At tutorial lectures, I've demonstrated ordinary CAT5 providing
RF rejection as good as shielded twisted pair into the high VHF range. And
I've solved more than a dozen instances of RFI to home entertainment systems
simply by replacing glorified zip cord with twisted pairs of #12 POC (plain,
ordinary copper).
For the same reason, twisted pair is superior for power wiring in our stations.
As to resistance -- I use the shortest practical runs of #10 between my power
source (a big 100Ah LiFePO4 battery) and my two K3s. I do this because like
most 12V radios, it's cleaner (lower levels of key clicks) at higher supply
voltages.
73, Jim K9YC
On Thu,8/11/2016 8:21 AM, rick jones via Elecraft wrote:
I just bought 20' of what was supposed to be 10GA zip wire from that auction
site. It is clearly marked as "Audiopipe 10 Gauge speaker cable". The
conductor is actually 12GA at best. Is this becoming common practice or is
wire going the way of 2X4 lumber? Suggestions for a reputable source of true
10GA PTFE zip wire for K3 power?
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