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Author Topic: Need elmer help...:(  (Read 1554 times)
KJ4JQU
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Posts: 36




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« on: January 05, 2013, 07:55:53 AM »

My house was built in 1968 and all the power lines in it are 2 conductor, no ground. In fact it seems the panel for my house is grounded to the water line (I think)..

Without a ground in my outlet for my equipment im assuming I will have to install a ground rod outside the window of my hamshack/room. And somehow connect all my equipment to that ground rod. In doing so, would that also take care of any RF issues in the shack?

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W2AEW
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« Reply #1 on: January 05, 2013, 08:14:14 AM »

My house was built in 1968 and all the power lines in it are 2 conductor, no ground. In fact it seems the panel for my house is grounded to the water line (I think)..

Without a ground in my outlet for my equipment im assuming I will have to install a ground rod outside the window of my hamshack/room. And somehow connect all my equipment to that ground rod. In doing so, would that also take care of any RF issues in the shack?

Are you sure there is no ground wire inside the receptacle box?  I had a house of the same vintage, and found that while all of the receptacles where two prong, there was a ground wire attached to the junction box behind the receptacle.  Over time, I replaced all of the receptacles with grounded receptacles by pigtailing an additional ground wire to the one in the box.

Of course, you certainly could install a ground rod and connect the ground connection of all your equipment to that.  No harm in that.  Will it get rid of RF issues in your shack?  Impossible to say for sure, but it's a definite possibility of a firm maybe.  Give it a try, couldn't hurt.
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KJ4JQU
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Posts: 36




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« Reply #2 on: January 05, 2013, 08:28:37 AM »

"definite possibility of a firm maybe"--Love that, will need to start using it at work!!

Yea I checked, my house is odd to say the least-no ground any where, really dont understand how this place hasnt burned down yet.

In my last set up I would sometimes get rf burned and those outlets were grounded, have a "choke" right before the feedline plugged into the tuner. Didnt seem to do much.
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WB6BYU
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« Reply #3 on: January 05, 2013, 08:54:23 AM »

Grounding is a very complex issue, because there are several different types / uses
of grounds, and what works well for one might not work at all for another.  It sounds
as though you are confusing the functions of an RF ground and an AC power safety
ground.

The purpose of the AC power safety ground (grounded wire in the outlet) is to prevent
there being a voltage difference between the chassis of your radio and the shield
of the coax coming in from your antenna, which could electrocute you when you
were touching both at the same time.  For this to work properly, the chassis and
anything connected to it needs to be reliably connected back to the ground or
neutral side of the power wiring, so an accidental short between the AC wiring
and chassis will blow the fuse rather than leaving the chassis hot and floating.
(Yes, this happened to me when I was using a power supply with a 2-wire cord:
it ended up that all the aluminum door frames in the apartment building were
live with 120VAC to ground.  We only avoided serious injury because the pebbled
concrete patio had a high resistance:  when I connected a wire between our
door frame and a nearby water faucet to ground off the "static charge" we were
feeling, the wire evaporated in a bright flash.)

If you add a ground rod to such a system, it should be tied back to the AC
power ground to prevent there being a voltage difference between the two
grounds.  (That can happen due to a poor ground rod installation:  I've measured
110VAC from the top of a ground rod to the dirt next to it when the rod wasn't
making good contact to the soil.)  If your AC system doesn't have a ground, then
the likely place to tie it would be the ground/neutral wiring in the main panel box,
in which case your rod would become the primary AC ground for the building.
You'll really want to check the AC wiring code on that.  (I know that the ground
rods for our recent electric system upgrade are buried and it isn't always
obvious that they are there.)


An RF ground is a separate matter:  a good AC power ground is NOT necessarily
a good RF ground (and vice versa).  Many stations do not need an RF ground,
and, if they do, it often should be at the antenna feedpoint rather than at the
shack.

If your problem is common mode current on the feedline (often the case with
antennas such as OCFD or end-fed wires where the outside of the coax is
acting as part of the antenna) then adding an RF ground may make make
the situation better or worse.  But if you only install the ground when
you are having problems, you aren't as likely to have a case where it makes
it worse, so, while sometimes it makes no difference, the remainder of the
cases contribute to the myth that an RF ground is the solution to the problem.
Actually, the solution is to properly decouple the feedline from the antenna
at the antenna.

If the shack is at a point of high RF voltage along the feedline (which is generally
the case when you are getting RF burns off the mic, etc.) then adding a choke
at that point (or very close to it, such as at the output of the tuner) isn't
going to help much:  at a high impedance point you need a much higher choke
impedance to be effective.  Putting the choke up by the feedpoint is likely to
work better, and if that isn't good enough, put another one about 1/4 of the
way down the feedline on the worst band.  You want to keep the RF off the
feedline in the first place, before it has a chance to build up to a high level
due to resonances.

Here is an example:  we have an OCFD antenna at the County EOC station,
and were plagued with noise pickup from the computer network.  This is
due to the same cause as RF in the shack, namely the outside of the coax
is acting a part of the antenna.  (Since it ran in close proximity to the
network cables, it picked up a lot of noise.)  Putting a choke at the rig end
didn't make any difference, but inserting it into a cable splice up on the roof
dropped the noise by 2 to 3 S-units, and the SWR curve looked much more
like what I had designed it to be.


So the problem with RF in the shack is unrelated to your AC power system -
as you observed previously.  You can fix one or the other, or both, but they
are due to very different causes and each should be treated separately.
« Last Edit: January 05, 2013, 08:58:40 AM by WB6BYU » Logged
W9GB
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Posts: 2659




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« Reply #4 on: January 05, 2013, 10:03:55 AM »

Quote
My house was built in 1968 and all the power lines in it are 2 conductor, no ground. In fact it seems the panel for my house is grounded to the water line (I think)..
M -

That is not uncommon.  
The 1970 National Electrical Code (NEC) introduced the usage of the Safety Ground (Green wire) to North American 120 VAC residential wiring.
This change occurred when my Dad was having a major addition to our 1910s built house in 1970.  While on vacation, the electrical was run as Romex 12-2 with NO ground.  While still legal in this municipality, I "pulled out" that cabling and replaced it with 12-2G (with safety ground) before inspections and Sheetrock.

Water pipe grounding, as you described, was common for 1960s MAIN Electrical Panels (residential).  Today, an outdoor Ground Rod is used.  Plumbing is moving to non-metallic composites and plastics -- so you can no longer assume usage as grounding conductor.

IF you have an electrician at your house, for electrical work in future,
I would have them inspect your main electrical panel for usage with an outdoor ground rod.

Your 1960s main panel MAY NOT have sufficient connections for Safety Ground conductor of circuits you desire to upgrade -- such as your AC outlets in the radio shack.
« Last Edit: January 05, 2013, 10:21:41 AM by W9GB » Logged
HARDEDGE
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Posts: 5




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« Reply #5 on: January 05, 2013, 11:37:24 AM »

Possible quick fix: Have an electrician come in and install a three-prong outlet, connecting the ground line on the outlet to the box itself. It's a common fix --assuming your electrical boxes are metal and your wiring is done through BX (steel armored) cable. Otherwise, have them run a 3-conductor, 20 amp Romex line from your service box to the room where your equipment is running and use that dedicated line for your gear.

DO NOT attempt this yourself unless you're a licensed electrician. If you don't know or are unsure of what you're doing you could blow up your radio or set fire to your house. If you haven't used a licensed electrician, your insurance won't cover the damage.

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K2OWK
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Posts: 1077




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« Reply #6 on: January 05, 2013, 02:37:39 PM »

I am an old guy so I am familiar with the two prong outlet system. The metal box that contained the outlets in the old house I lived in was tied to main fuse box. If I remember when the three prong system was introduced, and appliances started using a three prong plug an adapter from two to three prong was sold. This adapter had a green wire (ground) which was connected to the screw that held the socket plate in place, and giving the third prong on the plug a ground. In the house I lived in the panel ground was tied to the cold water pipe.

73s

K2OWK
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AA4PB
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Posts: 13032




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« Reply #7 on: January 05, 2013, 03:07:00 PM »

Under current codes, that wire going from the electrical service to the metal water pipes is NOT the ground connection. Conductive water pipes are required to be bonded to the electrical service ground in order to ensure that there can't be any voltage difference between the water pipes and the electrical ground. The electical service is required to have its own ground rod(s).
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K4RVN
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Posts: 812




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« Reply #8 on: January 05, 2013, 08:51:02 PM »

My electric panel is grounded to the copper water pipe in my house.  The electric company has a ground rod about 50 ft from my house at the pole which feeds my house. I have a ground rod I installed outside the shack and all my equipment, two amps two transceivers, power supplies all are connected to the gound rod. I also have a copper tubing ground going up to my copper water pipe which runs over my shack tied to the same ground rod. No RF problems at all. Could be luck, but has done well for me since March, 1966 in this house. One amp is on 240 volts, other is 120 volts. Transceivers, etc on 120 volts three prong plugs. My tower is grounded to another rod. As someone said, try installing a ground rod and see if it works. I would not urge any one to go messing with the electric panel grounding system from 1960s. My telephone is also grounded to the water pipe which was done by the telephone co.

Frank
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N4NYY
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Posts: 4820




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« Reply #9 on: January 06, 2013, 08:52:14 AM »

I ran a dedicated line to my shack. I would suggest you do the same. Maybe even insert a ground rod and grounding the panel there instead of plumbing.

On a side note, it sound like you have really dated electric service. Including safety, updating the service would be a huge selling when selling the house. Along with kitchen and bathroom. An investment in new electric is a worthwhile investment.
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WB2WIK
Member

Posts: 20666




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« Reply #10 on: January 06, 2013, 09:36:54 AM »

1968 was indeed before a ground wire to outlets was a universal requirement, so it is absolutely possible that all the wiring is 2-wire with no ground at all.  Not a good idea, but possible.

An earth ground for safety's sake is probably a good idea, although no assurance at all that this will offer any benefit for RF and operation of a ham station.  An "RF ground" is a significant investment in many cases and if casually done can create problems instead of solving any.

But experimentation is part of the hobby!
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