On 14 Jan 2015 at 0:34, Roger (K8RI) wrote:
On 1/12/2015 11:49 PM, KD7JYK DM09 wrote:
:I suppose if you're an expert at everything, there's no reason to try to :
help.
I know of no one who is an expert on everything. Actually I know a
number of knowledgeable people, but no experts.
I'm with you on this one (among others), Roger. I'm certainly no expert,
although I do know "some" things. ;-)
I'll repeat what I said before (as did several others) and ask some
questions. The remedies of RFI suppression have been pretty well
covered. Jim's tutorial does an excellent job of showing how to
suppress RF that gets in the line.
Yes. I have downloaded a portion of what Jim has on his site, and what little
of it I have so far been able to read is very informative and valuable.
*If these remedies have not worked, it's time to stop and look for
reasons!*
Indeed. I have not yet been able to implement many of Jim's (and other
excellent suggestions I have received here), but will as soon as I can.
I DID remove that 30+ feet of #8 un-connected "ground" wire
yesterday...whcih was "a job" in itself. The stuff is very stiff and wound
around all sorts of other wiring. I rolled it up with the idea of using it to
connect to the 8' ground rods I presently have in place. I intend to also add
other 8' ground rods as soon as the ground unfreezes here.
Is the problem really RF? If RF, it almost has to be common mode. There
has to be a reason why this particular setup is so prone to problems.
It's not just RF getting in, it's RF (Or Something. It could be AC, or
DC as well when the equipment is powered up) at a magnitude that is
frying the equipment. It again, (if nothing mentioned previously has
been overlooked)
Ha! Are you kidding? Of course something has been overlooked! :-)
That's why I posted my original question(s) to the forum! Like anyone else,
although I have had years of experience in various fields of investigation, I
certainly do not remember everything and must be reminded of some thing I
either forgot, or never ran into.
almost has to be something we'd not expect as the
regular approaches have not worked. Jim's air core resonant coil should
be effective at removing a specific narrow band of frequencies. Get too
many, or too few turns and they don't do much. (Old terms and thinking
die hard) while the chokes should suppress a wide range of
frequencies. They are wide band, but switching power supply
frequencies take more turns than the ham bands. OTOH the Power supplies
can have frequencies well up into the ham bands
Indeed!
Remember the RF getting into the house wiring and tripping GFIs. Might
this be a key?
Knob and Tube wiring in some areas.
Actually, there is very little K&T wiring left, and that which IS left is
impossible
to get to without a major dismantling of parts of the house. As far as I know
(!) the only K&T wiring left is a short run of lighting in the attic, and one
or two
wall plugs in the living room. (Hmmm...I'd better check those out...)
FYI, the house, a 2 story one, was built in the late 1800s, moved into its
present location in the 1930s, a basement was then installed under the
house (certain basement walls are over 3 feet thick), and electricity was
added about that time (remember the REA?), then the top of the house was
cut off since 2 story houses weren't "fashionable" at that time.
I did a major re-wiring of the house shortly after we moved into it, upgrading
all the wiring I could reach without ripping out walls or ceilings, bypassing
most of what I couldn't get to.
IF this is RF getting into the CAT5 why aren't the failures almost
immediate? (as has been noted previously)
Good question, which I have not been able to figure out. One significant
factor (which I have never been able to figure out either) is that the
"symptoms" change with the seasons. I suspect that the main reason is that
as the ground dries out, the ground resistance rises drastically, and during
the wet seasons, it falls drastically. Soil here is mostly hard clay, which when
it gets saturated is almost like some sort of thick soup, and when it is dry is
like concrete.
Loads connected and disconnected?
Are the failures temperature, or weather related.
Seasonal: see immediately above.
Knob and tube. I lived in a house like that many years ago. Normally,
"Knob and Tube" is only two wires with no ground wire so the outlets
would not have a proper ground even if they do have a ground. Knob and
Tube use only two pin sockets.. IE, they won't work with GFIs and
should never be part of a circuit that has GFIs. IE an extension.
Running a separate ground wire to outlets on knob and tube is begging
for problems and can be dangerous. A house with ham gear and computers
should have the K&T replaced and removed as soon as possible.
Done...at least as much as I was able to reach. As I said, the only bit of it
left,
as far as I know, is a short bit of lighting in the top floor (what's left of
the top
floor where the bedrooms are), which consists of two lights, one in each
upstairs bedroom.
However, now that I am reminded of it, there MAY be another bit which feeds
the bathroom... and the main computer room....which may be a big part of
the problem...although as I remember it, it is a run of #14 TH, installed by
those geology students I mentioned earlier. At least it terminates at the panel
as a #14TH...
It is absolutely impossible to get to without a major de-construction of the
house.
What is different about this setup besides the Knob and Tube? IIRC he
has a vertical that's fairly close. Do any of the radials come close to
the CAT5?
No.
Is the equipment "earthed" at each end?
Yes, AFAIK... I suppose I should check that...
Are the coax and
radials "earthed" at the base of the vertical.
Yes.
If so, are all
connections secure?
Yes.
Is the CAT5 a resonant length?
The run to the basement shack MAY be...it is around 62 feet long...a 50'
section, then a dumb-switch, then a 12' section.
Is there something
common between the rig and network?
Not that I know of.
I keep thinking Knob and Tube.
If removing the CAT5 eliminates the problem, disconnect it and measure
voltages to ground while transmitting.
Good idea.
Borrow an O-scope
I've got three good scopes, two Teks and an HP.
or spectrum
analyzer,
Don't have a working one. Wish I did. I have a non-working Tek or HP which
I got from the University of Idaho's EE dept, but it needs work...
but expect abnormally high voltages. If you are not familiar,
borrow the owner of the equipment too. That way you shouldn't be
responsible. A quick and check would be to disconnect the CAT5 and put
an NE51 between it and ground to see if it really is RF of substantial
voltage.
Ah. Good idea.
It would help to know the layout of the entire "wired" network. I lieu
of a drawing a good description might help
OK. I'll work on that...
Are the other computers still connected when the router/switch are
disconnected?
Yes.
Does your local ham club have an RFI group,
No.
or individuals well versed
in hunting down problems?
Only two of us... ;-)
If available make generous use of local brain
power.
Well, on that note, all hams in our small town and for a substantial distance
around it have been plagued with a terrible amount of RF noise for so long
most of them think it is normal! It is only since I and two other hams realized
that the noise level was unusually high that we have attempted to do
anything about it. Due to the fact that none of us has had any real time to
devote to it, progress has been very slow...but some progress has been
achieved.
In my case, where, on 80 meters, my "normal" noise level is a constant 10dB
over S-9, rising to 20dB over S-9 much of the time, we recently found a large
neon sign at a local pharmacy about 3 blocks from my home that when
switched off, reduces my noise level by 15 dB. Unfortunately, the owners
have not yet seen fit to find someone capable and knowledgeable enough to
permanently cure it, and I am reluctant to tackle the job since I don't carry
that specialized insurance needed for such a job.
A knowledgeable person, or persons present can do a lot more, quickly
than we can here.
Indeed. Yet this forum has proven to be extremely valuable to me before this
event.
I will relate a problem I had a while back, I had fried two relatively
expensive duoband (VHF/UHF) verticals which in turn took out some
expensive finals. The problem turned out to be a combination of a power
supply and grounding problem which all agreed shouldn't happen. I'm
still not sure about it, but with all grounds in place, its been working
for some time.
Knob and Tube...That is the main difference between this house and most
with ham stations and computers.
BTW At the risk of dating myself, when I was a kid, Knob and Tube was
not uncommon.
For me either, and I'm not averse to dating myself: I am 72, and was first
licensed in 1956. :-)
Thanks for the information and help, Roger.
vy 73,
Ken W7EKB