On Mon, 16 Dec 2013 13:42:54 -0500, Jerry Stuckle
wrote:

On 12/16/2013 12:54 PM, Jeff Liebermann wrote:
On Mon, 16 Dec 2013 07:46:16 -0500, Jerry Stuckle
wrote:

Then he has a problem in his ethernet. Properly installed, ethernet
creates virtually no interference.

Yes, that's the theory. If the cable isn't perfectly balanced, it
will become an antenna. Shielded ethernet adds additional
opportunities to radiate. Most of the RFI originates from ethernet
switches and routers.

It's more than just theory. Over the years, we've installed hundreds of
ethernet systems, with little or no interference.

Ummm... you check for RFI problems on hundreds of ethernet
installations? Perhaps I missed that section in the BICSI
certification guides. I don't recall any requirement to test for
excessive radiation, though it probably wouldn't be a bad idea. Good
to see that someone is conscientious about ethernet RFI. (Full
Disclosu I'm not certified but have skimmed the material).

The only time I check for radiation is when I install something for
hams. I have a cute little Alinco DJ-X2 HF receiver for sniffing, but
mostly it's just checking with the owners HF radio. Mostly, what I
find is noise originating from the wall warts and power supplies. The
switcher types are awful. I also find some rather noisy LED lighting,
plasma TV's, and computers. Once those are eliminated, the rest of
the noise is conducted by the ethernet wiring. I usually bring an
assortment of big ferrite beads with me to deal with those.

Shielded Category cable is much better - but you need to be careful. It
needs to be grounded at one end only (to prevent ground loops), and the
shield must carry through to the devices at the far end.

Agreed. Some countries (Switzerland) insist that all CAT5 be
shielded. Too bad that all of the pre-made shielded cables have
shield connections on both ends with no way to break the connection.
If you ground the source end of the cable, you end up with an antenna
and no shielding. Since ethernet has sources at both ends of the
cable, you have to ground both ends to get decent shielding.
See conclusions on Pg 31.
http://dallasemc.org/2010-10EMItroubleshooting.pdf
(Pages 26 thru 31 for ethernet).

The devices
must be shielded also, preferably in metal cases. Unfortunately, most
consumer-grade devices have plastic cases with little or no shielding
and do not connect to the shield. In cases like this, yes, the shield
can become a radiator. Commercial devices are better at this (but are a
lot more expensive).

Most of the 16, 24, and 48 port switches that I use are in metal
boxes. With all the RFI they generated, a shielded box is required to
pass FCC Part 15. Lately, I'm seeing "green" ethernet switches,
reduce power depending on CAT5 length.
http://www.dlinkgreen.com/energyefficiency.asp
Hopefully, that will reduce radiation by simply lowering transmit
power.

I find the consumer grade plastic boxes are tolerable. Some (i.e.
Linksys) have decent grounding systems. Others have internal shields.
However, I believe that cable shields are detrimental rather than
beneficial. The ability of the CAT5 cable to NOT radiate junk is
dependent on the balance between each wire in a twisted pair. If
anything unbalances the twisted pair, the CMMR is ruined, and the
wires radiate. (Reminder... wires radiate, components do not). Having
3 extra pairs of wires rubbing up against a pair of wires in the
bundle is bad enough for balance. In some CAT6 cables, a cross shaped
insulator runs down the length of the cable to keep the pairs
separated. However, if we add a shield, the capacitance between each
wire of a pair can be different depending on the spacing from the
shield. The change is not much, but sufficient to produce enough
unbalance for the pair to radiate. You can see the problem with a
length of shielded CAT5 and a capacitance meter. Measure the
capacitance from each wire in a pair to the shield. It may vary some
fraction of a PF, but that's enough to unbalance the pair and produce
some radiation. Also, note that it's not necessary for one wire out
of twisted pair to do the radiating. The RFI could easily be radiated
by wires from an adjacent pair if they were sufficiently well coupled.

One oddity are ethernet hubs. What goes in one port, goes out all the
other ports. With a switch, only data destined for a specific MAC
address on another port is passed. The problem is many older hubs
will send data to a port if a cable is inserted but not terminated.
They're not suppose to do that, but I've found a few old hubs that do
that. If you have an ethernet RFI problem, look into replacing hubs
with switches.

Again, that's the case with consumer-grade goods. Commercial grade are
much better at this.

I beg to differ. Hubs (repeaters) are quite different from switches
(multiport bridges) in operation. The problem is that the hubs will
transmit into a CAT5 cable with nothing at the other end. Common mode
rejection on the pair will prevent it from radiating. However, the
high VSWR caused by the lack of a termination, might cause it to
radiate.

"Understanding and Eliminating RF Interference" by Jim Brown K9YC
http://www.audiosystemsgroup.com/RFIHamNCCC.pdf
Start reading at Page 20 for the ethernet radiation section.
Mo
http://www.audiosystemsgroup.com/publish.htm

I think our expertise of doing this as a business for years in both
residential and commercial establishments qualifies us.

With all due respect, that sounds like bluster. You may very well
have had hundreds of successful installations, but I question if they
were all tested for RFI.

This thread may also be of interest:
http://lists.contesting.com/_rfi/2008-11/msg00025.html

Note that 100baseT is quieter than 10baseT. With 100baseT, the data
is first 4B5B encoded at 125Mbits/sec. To reduce crosstalk, it is
then scrambled and MLT-3 encoded. The result is a 31.2MHz carrier and
a mess of sidebands. The necessary scrambling has the side effect of
reducing high power peaks, and evening out the power spectrum over a
wider frequency range, thus reducing the RFI power at any given
frequency. It's much the same idea as the "spread spectrum"
modulation of computer clocks, to spread the power over a wider
frequency range, to meet FCC Part 15 requirements. So, instead of a
carrier or birdie, you'll hear broadband noise, which I guess is more
tolerable.

Again, it depends on the installation and equipment being used. But
10baseT is also old technology. 100baseT is more recent and solves a
lot of problems - both in radiation and susceptibility to interference
from external radiation.

Agreed. Things do depend on the equipment and installation.
Personally, I only do quality installations and use only the best
equipment. For example:
http://www.LearnByDestroying.com/jeffl/pics/drivel/slides/mess01.html
I've seen worse, but the owners didn't want me posting photos.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 16 Dec 2013 11:21:30 -0800, David Harmon
wrote:

On Sun, 15 Dec 2013 23:43:26 -0800 in rec.radio.amateur.antenna,
Jeff Liebermann wrote,
Marginally related RF drivel: One of my friends is avid DX'er. He
has all his media and computer gizmos interconnected via Wi-Fi because
Wi-Fi creates less RFI than ethernet.

Woah, how can that be? Would using shielded cat6 fix it?

I don't know. I don't have much experience with CAT6 STP as most of
my installations use CAT5e UTP cable (including for gigabit). It
might reduce radiation by shielding, or increase it if there's a
ground loop. In any case, the owner was not interested in wiring the
house, station, garage, antenna farm, front gate, home theater, etc
for ethernet. Wi-Fi did the job well enough and did not product RFI.

In retrospect, I probably should have spent more time finding the
exact sources of the HF interference. I did not make a systematic
check of the house, and did not check everything electrical in the
house. I didn't have the time as that would have taken days. Instead,
there was a large drop in RFI observed when the ethernet connected
devices were unplugged, so we went with that.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 16 Dec 2013 14:27:17 -0600, amdx wrote:

On 12/2/2013 12:39 AM, Jeff Liebermann wrote:
Comcast is now all digital in the People's Republic of Santa Cruz CA.

I got my cable bill a few days ago, noted it had increased $10.00.
Told the wife, she said ya, after Nov. the reduction I got last Nov.
expired. She went in, made her yearly complaint, but this time she
got a $20.00 discount! The bill dropped from $123.54 to $103.xx.
(Cable, phone and internet)
$240 a year, I think I'll taker her out for an ice cream cone. :-)
Mikek

Nice, but you can do better than giving her just an ice cream cone.

Do I get an ice cream cone if I suggest you drop the cable TV and
phone, and leave the internet. Then, switch to a VoIP provider and
watch IPTV via Netflix and such? My guess price is:
Comcast internet $50/month for first 12 months
Comcast internet $80/month after first 12 months
Future-Nine America Free $13.50/month
Netflix $8/month
Roku 3 media player $90
SIP phone (SPA941) $80
Send the ice cream to the address below.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 16 Dec 2013 19:25:12 -0800, Jeff Liebermann
wrote:

If you ground the source end of the cable, you end up with an antenna
and no shielding. Since ethernet has sources at both ends of the
cable, you have to ground both ends to get decent shielding.
See conclusions on Pg 31.
http://dallasemc.org/2010-10EMItroubleshooting.pdf
(Pages 26 thru 31 for ethernet).

Oops.
That should be "If you don't ground the source end of the cable..."

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 12/16/2013 10:25 PM, Jeff Liebermann wrote:
On Mon, 16 Dec 2013 13:42:54 -0500, Jerry Stuckle
wrote:

On 12/16/2013 12:54 PM, Jeff Liebermann wrote:
On Mon, 16 Dec 2013 07:46:16 -0500, Jerry Stuckle
wrote:

Then he has a problem in his ethernet. Properly installed, ethernet
creates virtually no interference.

Yes, that's the theory. If the cable isn't perfectly balanced, it
will become an antenna. Shielded ethernet adds additional
opportunities to radiate. Most of the RFI originates from ethernet
switches and routers.

It's more than just theory. Over the years, we've installed hundreds of
ethernet systems, with little or no interference.

Ummm... you check for RFI problems on hundreds of ethernet
installations? Perhaps I missed that section in the BICSI
certification guides. I don't recall any requirement to test for
excessive radiation, though it probably wouldn't be a bad idea. Good
to see that someone is conscientious about ethernet RFI. (Full
Disclosu I'm not certified but have skimmed the material).


Where it's necessary, yes. And in most commercial installations, it is
necessary. It really doesn't take long, unless it's a huge install.
And no, it isn't part of the BICSI guidelines - but they also aren't the
bottom line in certifications (although they would like to think they are).

The only time I check for radiation is when I install something for
hams. I have a cute little Alinco DJ-X2 HF receiver for sniffing, but
mostly it's just checking with the owners HF radio. Mostly, what I
find is noise originating from the wall warts and power supplies. The
switcher types are awful. I also find some rather noisy LED lighting,
plasma TV's, and computers. Once those are eliminated, the rest of
the noise is conducted by the ethernet wiring. I usually bring an
assortment of big ferrite beads with me to deal with those.


As I said - many commercial installations need it, also.

Shielded Category cable is much better - but you need to be careful. It
needs to be grounded at one end only (to prevent ground loops), and the
shield must carry through to the devices at the far end.

Agreed. Some countries (Switzerland) insist that all CAT5 be
shielded. Too bad that all of the pre-made shielded cables have
shield connections on both ends with no way to break the connection.
If you ground the source end of the cable, you end up with an antenna
and no shielding. Since ethernet has sources at both ends of the
cable, you have to ground both ends to get decent shielding.
See conclusions on Pg 31.
http://dallasemc.org/2010-10EMItroubleshooting.pdf
(Pages 26 thru 31 for ethernet).


No, you do not end up with an antenna if you ground only the source end.
But grounding it at both ends creates a ground loop. This was a
recognized problem even back in the 70's, when I was working for IBM and
we had video terminals on the ends of up to 3000 ft. of coax.

I think you are missing the point here. Terminating the shield at both
ends is not the same as grounding the shield at both ends.

The devices
must be shielded also, preferably in metal cases. Unfortunately, most
consumer-grade devices have plastic cases with little or no shielding
and do not connect to the shield. In cases like this, yes, the shield
can become a radiator. Commercial devices are better at this (but are a
lot more expensive).

Most of the 16, 24, and 48 port switches that I use are in metal
boxes. With all the RFI they generated, a shielded box is required to
pass FCC Part 15. Lately, I'm seeing "green" ethernet switches,
reduce power depending on CAT5 length.
http://www.dlinkgreen.com/energyefficiency.asp
Hopefully, that will reduce radiation by simply lowering transmit
power.


All items which generate rf (which includes basically anything with
digital signals) must pass FCC Part 15. But there are two sections in
Part 15 - Part A (residential) and Part B (commercial), Part A is more
stringent, but you will notice that most devices are Part B certified.
But that also does not mean they will not cause interference; it only
means the interference they cause is within certain limits.

I find the consumer grade plastic boxes are tolerable. Some (i.e.
Linksys) have decent grounding systems. Others have internal shields.
However, I believe that cable shields are detrimental rather than
beneficial. The ability of the CAT5 cable to NOT radiate junk is
dependent on the balance between each wire in a twisted pair. If
anything unbalances the twisted pair, the CMMR is ruined, and the
wires radiate. (Reminder... wires radiate, components do not). Having
3 extra pairs of wires rubbing up against a pair of wires in the
bundle is bad enough for balance. In some CAT6 cables, a cross shaped
insulator runs down the length of the cable to keep the pairs
separated. However, if we add a shield, the capacitance between each
wire of a pair can be different depending on the spacing from the
shield. The change is not much, but sufficient to produce enough
unbalance for the pair to radiate. You can see the problem with a
length of shielded CAT5 and a capacitance meter. Measure the
capacitance from each wire in a pair to the shield. It may vary some
fraction of a PF, but that's enough to unbalance the pair and produce
some radiation. Also, note that it's not necessary for one wire out
of twisted pair to do the radiating. The RFI could easily be radiated
by wires from an adjacent pair if they were sufficiently well coupled.


You can believe all you want. But my experience is much different. For
instance, the presence of a shield actually improves balance in the
wires; the way wires are twisted in a pair averages the distance to the
shield to be the same. A fraction of a pf is not going to significantly
unbalance anything - nothing is perfect, anyway. However, when running
a cable, bringing it near anything metal (even nails in the wall) can
unbalance unshielded category cable, while shielded category cable
minimizes the effects of external metal.

And different pairs have different twists to limit coupling between wires.

One oddity are ethernet hubs. What goes in one port, goes out all the
other ports. With a switch, only data destined for a specific MAC
address on another port is passed. The problem is many older hubs
will send data to a port if a cable is inserted but not terminated.
They're not suppose to do that, but I've found a few old hubs that do
that. If you have an ethernet RFI problem, look into replacing hubs
with switches.

Again, that's the case with consumer-grade goods. Commercial grade are
much better at this.

I beg to differ. Hubs (repeaters) are quite different from switches
(multiport bridges) in operation. The problem is that the hubs will
transmit into a CAT5 cable with nothing at the other end. Common mode
rejection on the pair will prevent it from radiating. However, the
high VSWR caused by the lack of a termination, might cause it to
radiate.


It doesn't make any difference whether you are talking hubs or switches.
Some consumer cheap grade hubs may transmit into unterminated lines.
But better consumer grade and commercial grade hubs will not. They
detect the presence/absence of a device on the other end and operate
accordingly.

"Understanding and Eliminating RF Interference" by Jim Brown K9YC
http://www.audiosystemsgroup.com/RFIHamNCCC.pdf
Start reading at Page 20 for the ethernet radiation section.
Mo
http://www.audiosystemsgroup.com/publish.htm

I think our expertise of doing this as a business for years in both
residential and commercial establishments qualifies us.

With all due respect, that sounds like bluster. You may very well
have had hundreds of successful installations, but I question if they
were all tested for RFI.


I don't really care what you think. And I didn't say they all were
tested for RFI - but a good percentage of them were.

But it sounds like even if we only tested one for RFI, it would be one
more than you have ever done.

This thread may also be of interest:
http://lists.contesting.com/_rfi/2008-11/msg00025.html

Note that 100baseT is quieter than 10baseT. With 100baseT, the data
is first 4B5B encoded at 125Mbits/sec. To reduce crosstalk, it is
then scrambled and MLT-3 encoded. The result is a 31.2MHz carrier and
a mess of sidebands. The necessary scrambling has the side effect of
reducing high power peaks, and evening out the power spectrum over a
wider frequency range, thus reducing the RFI power at any given
frequency. It's much the same idea as the "spread spectrum"
modulation of computer clocks, to spread the power over a wider
frequency range, to meet FCC Part 15 requirements. So, instead of a
carrier or birdie, you'll hear broadband noise, which I guess is more
tolerable.

Again, it depends on the installation and equipment being used. But
10baseT is also old technology. 100baseT is more recent and solves a
lot of problems - both in radiation and susceptibility to interference
from external radiation.

Agreed. Things do depend on the equipment and installation.
Personally, I only do quality installations and use only the best
equipment. For example:
http://www.LearnByDestroying.com/jeffl/pics/drivel/slides/mess01.html
I've seen worse, but the owners didn't want me posting photos.



Low voltage systems have been our business for over 10 years. We
wouldn't have a successful business if we did crap.

And it is our full-time business, not some sideline.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On 12/16/2013 10:44 PM, Jeff Liebermann wrote:
On Mon, 16 Dec 2013 11:21:30 -0800, David Harmon
wrote:

On Sun, 15 Dec 2013 23:43:26 -0800 in rec.radio.amateur.antenna,
Jeff Liebermann wrote,
Marginally related RF drivel: One of my friends is avid DX'er. He
has all his media and computer gizmos interconnected via Wi-Fi because
Wi-Fi creates less RFI than ethernet.

Woah, how can that be? Would using shielded cat6 fix it?

I don't know. I don't have much experience with CAT6 STP as most of
my installations use CAT5e UTP cable (including for gigabit). It
might reduce radiation by shielding, or increase it if there's a
ground loop. In any case, the owner was not interested in wiring the
house, station, garage, antenna farm, front gate, home theater, etc
for ethernet. Wi-Fi did the job well enough and did not product RFI.

In retrospect, I probably should have spent more time finding the
exact sources of the HF interference. I did not make a systematic
check of the house, and did not check everything electrical in the
house. I didn't have the time as that would have taken days. Instead,
there was a large drop in RFI observed when the ethernet connected
devices were unplugged, so we went with that.



Actually, if you have the right equipment, you can narrow it down in a
very short time. It seldom takes us more than an hour to find RFI
problems, and most can be done in 10-15 minutes. It never takes us
days, even in large installations.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.

==================

On 12/16/2013 9:58 PM, Jeff Liebermann wrote:
On Mon, 16 Dec 2013 14:27:17 -0600, amdx wrote:

On 12/2/2013 12:39 AM, Jeff Liebermann wrote:
Comcast is now all digital in the People's Republic of Santa Cruz CA.

I got my cable bill a few days ago, noted it had increased $10.00.
Told the wife, she said ya, after Nov. the reduction I got last Nov.
expired. She went in, made her yearly complaint, but this time she
got a $20.00 discount! The bill dropped from $123.54 to $103.xx.
(Cable, phone and internet)
$240 a year, I think I'll taker her out for an ice cream cone. :-)
Mikek

Nice, but you can do better than giving her just an ice cream cone.

Do I get an ice cream cone if I suggest you drop the cable TV and
phone, and leave the internet. Then, switch to a VoIP provider and
watch IPTV via Netflix and such? My guess price is:
Comcast internet $50/month for first 12 months
Comcast internet $80/month after first 12 months
Future-Nine America Free $13.50/month
Netflix $8/month
Roku 3 media player $90
SIP phone (SPA941) $80
Send the ice cream to the address below.


I like my Foxnews network, otherwise dropping cable would
be easier. I did a short search of IPTV and only found Kansas
has googlefiber with a managed IPTV service. I'm not sure what
that all means, but the little reasearch I did, I don't think I could
have Foxnews on IPTV via Netflix, yet.
As I've said before, my kids got Netflix and never concerned
themselves with cable.
Mikek
PS. I'm mulling over the logistics of sending an ice cream cone from Fl.
to Ca. :-)

On 12/17/2013 9:28 AM, amdx wrote:
On 12/16/2013 9:58 PM, Jeff Liebermann wrote:
On Mon, 16 Dec 2013 14:27:17 -0600, amdx wrote:

On 12/2/2013 12:39 AM, Jeff Liebermann wrote:
Comcast is now all digital in the People's Republic of Santa Cruz CA.

I got my cable bill a few days ago, noted it had increased $10.00.
Told the wife, she said ya, after Nov. the reduction I got last Nov.
expired. She went in, made her yearly complaint, but this time she
got a $20.00 discount! The bill dropped from $123.54 to $103.xx.
(Cable, phone and internet)
$240 a year, I think I'll taker her out for an ice cream cone. :-)
Mikek

Nice, but you can do better than giving her just an ice cream cone.

Do I get an ice cream cone if I suggest you drop the cable TV and
phone, and leave the internet. Then, switch to a VoIP provider and
watch IPTV via Netflix and such? My guess price is:
Comcast internet $50/month for first 12 months
Comcast internet $80/month after first 12 months
Future-Nine America Free $13.50/month
Netflix $8/month
Roku 3 media player $90
SIP phone (SPA941) $80
Send the ice cream to the address below.


I like my Foxnews network, otherwise dropping cable would
be easier. I did a short search of IPTV and only found Kansas
has googlefiber with a managed IPTV service. I'm not sure what
that all means, but the little reasearch I did, I don't think I could
have Foxnews on IPTV via Netflix, yet.
As I've said before, my kids got Netflix and never concerned
themselves with cable.
Mikek
PS. I'm mulling over the logistics of sending an ice cream cone from Fl.
to Ca. :-)

Other problems with Netflix include lack of live sports and limited
local channels. Some of these are available via the internet (for a
price, of course, which must also be factored in). But some, like major
league baseball, are blacked out on the internet if you're in their
local area; i.e. we can't get either the Baltimore Orioles or Washington
Nationals via the internet here in the Washington, DC area.

Sure, you could use a proxy somewhere else, but that's against their TOS
and if you're caught they will cancel your account with no refund.

Additionally, VOIP has had problems in the past, but is getting better.
Commercial grade VOIP is pretty solid, but costs more. Consumer grade
is more prone to dropped calls and dropouts, but is getting a lot
better. Also, the cheaper services are more prone to problems than the
more expensive ones. And some phones will not allow more than one
extension to be active concurrently (i.e. you can't have two people on
the phone on your end talking to someone else).

Just some things to check for if they are important to you.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On Tue, 17 Dec 2013 08:28:16 -0600, amdx wrote:

I like my Foxnews network, otherwise dropping cable would
be easier.

When you buy a Roku or similar screaming media player, you get a mess
of "channels" with it. All they do is point to sources of streaming
media all over the internet. FoxNoise is one of those:
http://www.roku.com/channels/#!details/2946/fox-news-channel

I did a short search of IPTV and only found Kansas
has googlefiber with a managed IPTV service. I'm not sure what
that all means, but the little reasearch I did, I don't think I could
have Foxnews on IPTV via Netflix, yet.

IPTV simply means watching television over something that spits
internet protocol packets. For example, I watch TV over a rather
slothish 1.5Mbit/sec DSL line. Netflix and some others adjust their
compression and speed to match the line speed, so they work just fine.
Other's just belch at higher rates resulting in the dreaded
"buffering" delays. Still others insist on downloading short clips
(about 5 min) into the media player buffer, before playing. IPTV is
far from a perfect replacement for cable or satellite TV, but it's
getting better.

A few more details...

If you're into playing recorded videos, look into setting up a Plex
media server:
http://www.plexapp.com

Netflix does not do local programming. So, if you want that, setup an
outside TV antenna and watch OTA (over the air) TV.

To me, the real benefit of watching Netflix over cable or satellite TV
is the lack of commercials.

As I've said before, my kids got Netflix and never concerned
themselves with cable.

Good. The kids can set it up for you.

Mikek
PS. I'm mulling over the logistics of sending an ice cream cone from Fl.
to Ca. :-)

A gift certificate from the local dispensary will suffice:
http://www.lovemariannes.com
I'm partial to (dark) chocolate chip.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 17 Dec 2013 07:42:01 -0500, Jerry Stuckle
wrote:

Actually, if you have the right equipment, you can narrow it down in a
very short time.

What is the right equipment? A portable spectrum analyzer is not in
my budget and my bench test equipment is too heavy for sniffing in the
field. I'm fairly well equipped for 2.4GHz wi-fi interference, but
not for HF.

It seldom takes us more than an hour to find RFI
problems, and most can be done in 10-15 minutes. It never takes us
days, even in large installations.

Impressive. I assume those are continuously generating RFI sources,
not sources that appear intermittently or drift all over the place as
they warm up. I spent about a month chasing down a noise source that
turned out to be the 24v battery charger on a diesel generator. Some
grid tied solar controllers seem to be problems and take some time to
find because they can be miles away. Fortunately, they're usually
easily fixed with the manufacturers optional filter kit. It took me
about a week to determine that my weather station was the source of
some 20 meter trash. The problem was that it only generated noise
when running on the internal backup battery, and not on AC power. The
ones that disappear when the AC power is temporarily turned off are
usually quite easy. The one's that don't take me much longer to find.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558